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• is there a general accounting system database schema which i can use ?

  - by soden

  i require a generic accounting system database schema is there any sites which provide this ?

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• How do I map nested generics in NHibernate

  - by Gluip

  In NHibernate you can map generics like this <class name="Units.Parameter`1[System.Int32], Units" table="parameter_int" > </class> But how can I map a class like this? Set<T> where T is a Parameter<int> like this Set<Parameter<int>> My mapping hbm.xml looking like this fails <class name="Set`1[[Units.Parameter`1[System.Int32], Units]],Units" table="settable"/> I simplified my mappings a little to get my point accross very clearly. Basically I want NHibernate to map generic class which has has generic type parameter. Want I understand from googling around is that NHibernate is not able to parse the name to the correct type in TypeNameParser.Parse() which result in the following error when adding the mapping to the configuration System.ArgumentException: Exception of type 'System.ArgumentException' was thrown. Parameter name: typeName@31 Anybody found a way around this limitation?

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• java overloaded method

  - by Sean Nguyen

  Hi, I have an abstract template method: class abstract MyTemplate { public void something(Object obj) { doSomething(obj) } protected void doSomething(Object obj); } class MyImpl extends MyTemplate { protected void doSomething(Object obj) { System.out.println("i am dealing with generic object"); } protected void doSomething(String str) { System.out.println("I am dealing with string"); } } public static void main(String[] args) { MyImpl impl = new MyImpl(); impl.something("abc"); // --> this return "i am dealing with generic object" } How can I print "I am dealing with string" w/o using instanceof in doSomething(Object obj)? Thanks,

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• In ASP.NET MVC, how does response.redirect work?

  - by Swoop

  I have used response.redirect in classic ASP and ASP.NET webforms. However, with MVC 2.0, I am running into something peculiar. I have a private method in a controller class that is used by multiple controller methods to help load and validate some information. This private method is setup to redirect if a problem is discovered to a generic error message page. The big problem I am noticing is that the calling controller class and page view attempt to complete rendering and loading before the redirect actually takes place. This is annoying in development because the View throws exceptions that I need to ignore before my generic error page finally loads. As mentioned above, I am used to the older model of response.redirect which prevented subsequent code on a page from being executed as the new page would then load. Any help or advice on redirects in MVC would be greatly appreciated.

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• boost variant static_visitor problem picking correct function

  - by Steve

  I'm sure I'm having a problem with template resolution here, but I'm not sure why I'm having the problem. I have a static visitor I'm passing to boost variant where i've had to do template specialization for certain cases. The case for everything except for MyClass should throw in the static_visitor below. Unfortunately, when the visitor is applied to pull a MyClass out, it selects the most generic case rather than the exact match. I would type each case explicitly, but that will be rather long. So, why is the compiler resolving the most generic case over the exact match, and is there anyway to fix it template<> class CastVisitor<MyClass>:public boost::static_visitor<MyClass> { public: template<typename U> MyClass operator()(const U & i) const { throw std::exception("Unable to cast"); } MyClass operator()(const MyClass& i) { return i; } };

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• Sort objects and polymorphism

  - by ritmbo

  Suppose I have a class A. And B and C are child of A. Class A has a generic algorithm for sorting arrays of type A, so that I could use it for B and C without writing again the algorithm for each. In the algorithm, sometimes I have to swap. The problem is that I can only see the objects as type A, and if I do: A aux = array[i] array[i] = array[j] array[j] = aux I think I have a problem. Because array[i], maybe its of type B, and aux is of type A, so I think I'm losing information. I'm sure u understand this situation... how can I sort a generic array of objects using a father method algorithm?

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• int i vs int index etc. Which one is better?

  - by Earlz

  Coming from a C background I've always used int i for generic loop variables. Of course in big nested loops or other complex things I may use a descriptive name but which one had you rather see? int i; for(i=0;i<Controls.Count;i++){ DoStuff(Controls[i]); } or int index; for(index=0;index<Controls.Count;index++){ DoStuff(Controls[index]); } In the current project I am working on there are both of these styles and index being replaced by ndx. Which one is better? Is the i variable too generic? Also what about the other C style names? i, j, k Should all of these be replaced by actual descriptive variables?

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• How to add javascript to YII correctly?

  - by RD.

  I want to create several javascript function that will be needed on different pages. Most will be relevant only to one page, but some to several. I know if I add general conversion functions, it would be a good idea to just create a new javascript file and put all these generic functions into that one file. Bringing me to my first question: Where would you store the generic javascript file? In "protected"? Which subfolder? Then, I need to address the placement of other javascript code. If I have javascript that will only be used on one page, should I use this technique or should I stick to a similar approach as above? The emphasis is on doing it correctly. I want to fall exactly in line with the yii framework.

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• After upgrading to 2.6.35-24 kernel, why does adb no longer list devices?

  - by nbolton

  When I first installed Ubuntu 10.10 64-bit, I was able to see a physical Android device (connected via USB) in the Android Device Chooser (launched from Eclipse). But, after upgrading my kernel from 2.6.35-22-generic to 2.6.35-24-generic, no devices are listed any more, and I am unable to see any results when running adb devices like so: $ ./adb devices List of devices attached $ I have tried booting in the previous kernel version, but I get some udev error, so I was hoping I could get it working with the newer kernel version. I figured SO was the best place for this question, as it seems more developer related.

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• Resolve property at runtime. C#

  - by user1031381

  I have some class which have some code public IEnumerable<TypeOne> TypeOne { get { if (db != null) { var col = db.Select<TypeOne>(); if (col.Count > 0) return col; } return db2.TypeOne; } } public IEnumerable<TypeTwo> TypeTwo { get { if (db != null) { var col = db.Select<TypeTwo>(); if (col.Count > 0) return col; } return db2.TypeTwo; } } So as You can see there is a lot of duplicated Code and there are same property name and item type of enumerable. I want to call some property of object like "obj.MyProp". And MyProp must be resolved at runtime with some generic or non-generic method. Is it possible?

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• C# Deserializing to a dictionary<string, Object>

  - by lovecraft

  I'm writing a C#/VB application to connect to a database and do stuff with the data. I was given this code to take a serialized byte array and deserialized it, which is then written to a Dictionary The line of code is: Dictionary<string, Object> DictionaryEmployee = (Dictionary<string, Object> Deserializer(byteArrayEmp)); The errors I'm getting are exceedingly unhelpful. "Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement" if I mouse over Object and "Using the generic type 'System.Collections.Generic.Dictionary' requires 2 type arguments if I mouse over Dictionary.

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• How to see if type is instance of a class in Haskell?

  - by Raekye

  I'm probably doing this completely wrong (the unhaskell way); I'm just learning so please let me know if there's a better way to approach this. Context: I'm writing a bunch of tree structures. I want to reuse my prettyprint function for binary trees. Not all trees can use the generic Node/Branch data type though; different trees need different extra data. So to reuse the prettyprint function I thought of creating a class different trees would be instances of: class GenericBinaryTree a where is_leaf :: a -> Bool left :: a -> a node :: a -> b right :: a -> a This way they only have to implement methods to retrieve the left, right, and current node value, and prettyprint doesn't need to know about the internal structure. Then I get down to here: prettyprint_helper :: GenericBinaryTree a => a -> [String] prettyprint_helper tree | is_leaf tree = [] | otherwise = ("{" ++ (show (node tree)) ++ "}") : (prettyprint_subtree (left tree) (right tree)) where prettyprint_subtree left right = ((pad "+- " "| ") (prettyprint_helper right)) ++ ((pad "`- " " ") (prettyprint_helper left)) pad first rest = zipWith (++) (first : repeat rest) And I get the Ambiguous type variable 'a0' in the constraint: (Show a0) arising from a use of 'show' error for (show (node tree)) Here's an example of the most basic tree data type and instance definition (my other trees have other fields but they're irrelevant to the generic prettyprint function) data Tree a = Branch (Tree a) a (Tree a) | Leaf instance GenericBinaryTree (Tree a) where is_leaf Leaf = True is_leaf _ = False left (Branch left node right) = left right (Branch left node right) = right node (Branch left node right) = node I could have defined node :: a -> [String] and deal with the stringification in each instance/type of tree, but this feels neater. In terms of prettyprint, I only need a string representation, but if I add other generic binary tree functions later I may want the actual values. So how can I write this to work whether the node value is an instance of Show or not? Or what other way should I be approaching this problem? In an object oriented language I could easily check whether a class implements something, or if an object has a method. I can't use something like prettyprint :: Show a => a -> String Because it's not the tree that needs to be showable, it's the value inside the tree (returned by function node) that needs to be showable. I also tried changing node to Show b => a -> b without luck (and a bunch of other type class/preconditions/whatever/I don't even know what I'm doing anymore).

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• Mozilla Weave can't sync Firefox. What's wrong?

  - by Mehper C. Palavuzlar

  For the last few days, Mozilla Weave can't sync. Below is the activity log. Any ideas? 2010-05-02 20:47:15 Service.Main WARN Unknown error while downloading metadata record. Aborting sync. 2010-05-02 20:47:15 Service.Main CONFIG Starting backoff, next sync at:Sun May 02 2010 21:16:09 GMT+0300 (GTB Yaz Saati) 2010-05-02 20:47:15 Service.Main DEBUG Exception: aborting sync, remote setup failed No traceback available 2010-05-02 21:16:09 Service.Main DEBUG Idle timer created for sync, will sync after 5 seconds of inactivity. 2010-05-02 21:16:30 Net.Resource DEBUG GET success 200 https://sj-weave03.services.mozilla.com/1.0/mehper/storage/meta/global 2010-05-02 21:16:30 Service.Main DEBUG Weave Version: 1.2.3 Local Storage: 2 Remote Storage: 2 2010-05-02 21:26:50 Net.Resource DEBUG GET success 200 https://sj-weave03.services.mozilla.com/1.0/mehper/info/collections 2010-05-02 21:26:50 Engine.Clients INFO 0 outgoing items pre-reconciliation 2010-05-02 21:26:50 Engine.Clients INFO Records: 0 applied, 0 reconciled, 0 left to fetch 2010-05-02 21:26:50 Engine.Clients DEBUG Total (ms): sync 6, processIncoming 3, uploadOutgoing 0, syncStartup 3, syncFinish 0 2010-05-02 21:26:50 Engine.Bookmarks INFO 0 outgoing items pre-reconciliation 2010-05-02 21:26:50 Engine.Bookmarks INFO Records: 0 applied, 0 reconciled, 0 left to fetch 2010-05-02 21:26:50 Engine.Bookmarks DEBUG Total (ms): sync 13, processIncoming 5, uploadOutgoing 0, syncStartup 3, syncFinish 3 2010-05-02 21:26:50 Engine.Forms INFO 1 outgoing items pre-reconciliation 2010-05-02 21:26:50 Engine.Forms INFO Records: 0 applied, 0 reconciled, 0 left to fetch 2010-05-02 21:26:50 Engine.Forms INFO Uploading all of 1 records 2010-05-02 21:26:50 Collection DEBUG POST Length: 388 2010-05-02 21:27:06 Collection DEBUG POST success 200 https://sj-weave03.services.mozilla.com/1.0/mehper/storage/forms 2010-05-02 21:27:06 Engine.Forms DEBUG Total (ms): sync 15924, processIncoming 3, uploadOutgoing 15918, syncStartup 3, syncFinish 0, createRecord 1 2010-05-02 21:27:06 Engine.History INFO 55 outgoing items pre-reconciliation 2010-05-02 21:27:06 Engine.History INFO Records: 0 applied, 0 reconciled, 0 left to fetch 2010-05-02 21:27:09 Engine.History INFO Uploading all of 55 records 2010-05-02 21:27:09 Collection DEBUG POST Length: 35337 2010-05-02 21:27:32 Collection DEBUG POST success 200 https://sj-weave03.services.mozilla.com/1.0/mehper/storage/history 2010-05-02 21:27:32 Engine.History DEBUG Total (ms): sync 25588, processIncoming 4, uploadOutgoing 25580, syncStartup 3, syncFinish 0, createRecord 2540 2010-05-02 21:27:32 Engine.Passwords INFO 0 outgoing items pre-reconciliation 2010-05-02 21:27:32 Engine.Passwords INFO Records: 0 applied, 0 reconciled, 0 left to fetch 2010-05-02 21:27:32 Engine.Passwords DEBUG Total (ms): sync 8, processIncoming 4, uploadOutgoing 0, syncStartup 4, syncFinish 0 2010-05-02 21:27:32 Engine.Prefs INFO 0 outgoing items pre-reconciliation 2010-05-02 21:27:32 Engine.Prefs INFO Records: 0 applied, 0 reconciled, 0 left to fetch 2010-05-02 21:27:32 Engine.Prefs DEBUG Total (ms): sync 8, processIncoming 3, uploadOutgoing 0, syncStartup 4, syncFinish 0 2010-05-02 21:27:32 Engine.Tabs INFO 1 outgoing items pre-reconciliation 2010-05-02 21:27:32 Engine.Tabs INFO Records: 0 applied, 0 reconciled, 0 left to fetch 2010-05-02 21:27:32 Engine.Tabs INFO Uploading all of 1 records 2010-05-02 21:27:32 Collection DEBUG POST Length: 393 2010-05-02 21:27:54 Collection DEBUG POST success 200 https://sj-weave03.services.mozilla.com/1.0/mehper/storage/tabs 2010-05-02 21:27:54 Engine.Tabs DEBUG Total (ms): sync 21943, processIncoming 3, uploadOutgoing 21936, syncStartup 3, syncFinish 0, createRecord 8 2010-05-02 21:27:54 Service.Main INFO Sync completed successfully 2010-05-02 22:27:53 Service.Main DEBUG Idle timer created for sync, will sync after 5 seconds of inactivity. 2010-05-02 22:28:14 Net.Resource DEBUG GET success 200 https://sj-weave03.services.mozilla.com/1.0/mehper/storage/meta/global 2010-05-02 22:28:14 Service.Main DEBUG Weave Version: 1.2.3 Local Storage: 2 Remote Storage: 2 2010-05-02 22:28:16 Net.Resource DEBUG GET fail 503 https://sj-weave03.services.mozilla.com/1.0/mehper/info/collections 2010-05-02 22:28:16 Service.Main DEBUG Exception: aborting sync, failed to get collections No traceback available 2010-05-02 23:28:15 Service.Main DEBUG Idle timer created for sync, will sync after 5 seconds of inactivity. 2010-05-03 00:26:42 Service.Main DEBUG Exception: Could not acquire lock No traceback available 2010-05-03 00:31:03 RecordMgr DEBUG Failed to import record: App. Quitting JS Stack trace: Res__request(...)@resource.js:208 < Res_get()@resource.js:271 < RecordMgr_import("https://sj-weave03.services.mozilla.com/1.0/mehper/storage/meta/global")@wbo.js:119 < WeaveSvc__remoteSetup()@service.js:824 < ()@service.js:1187 < WrappedNotify()@util.js:114 < WrappedLock()@util.js:86 < WrappedCatch()@util.js:65 < sync(false)@service.js:1146 < ([object Object])@service.js:414 < notify([object XPCWrappedNative_NoHelper])@util.js:629 2010-05-03 00:31:03 Service.Main DEBUG Weave Version: 1.2.3 Local Storage: 2 Remote Storage: 2010-05-03 00:31:03 Service.Main WARN Unknown error while downloading metadata record. Aborting sync. 2010-05-03 00:31:03 Service.Main DEBUG Exception: aborting sync, remote setup failed No traceback available 2010-05-03 17:26:25 Service.Main INFO Loading Weave 1.2.3 2010-05-03 17:26:25 Engine.Bookmarks DEBUG Engine initialized 2010-05-03 17:26:25 Engine.Forms DEBUG Engine initialized 2010-05-03 17:26:25 Engine.History DEBUG Engine initialized 2010-05-03 17:26:25 Engine.Passwords DEBUG Engine initialized 2010-05-03 17:26:25 Engine.Prefs DEBUG Engine initialized 2010-05-03 17:26:25 Engine.Tabs DEBUG Engine initialized 2010-05-03 17:26:25 Engine.Tabs DEBUG Resetting tabs last sync time 2010-05-03 17:26:25 Service.Main INFO Mozilla/5.0 (Windows; U; Windows NT 6.1; tr; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3 (.NET CLR 3.5.30729) 2010-05-03 17:26:26 Service.Main DEBUG Caching URLs under storage user base: https://sj-weave03.services.mozilla.com/1.0/mehper/ 2010-05-03 17:26:30 Service.Main DEBUG Autoconnecting in 3 seconds 2010-05-03 17:26:36 Service.Main INFO Logging in user mehper 2010-05-03 17:45:46 Service.Main DEBUG Exception: Could not acquire lock No traceback available 2010-05-03 17:53:18 Service.Main DEBUG Exception: Could not acquire lock No traceback available

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• Disk operations freeze Debian

  - by Grzenio

  Hi, I have just installed Debian testing on my new desktop and I am not very happy with performance - when I perform a disk intensive operation, e.g. upgrade packages in the system, everything seems to freeze, e.g. changing tabs in Iceweasel takes 3 seconds. I run the Debian on my 3 year old Thinkpad X60 ultra-portable, and I don't have these issues. (every single parameter of the laptop is much worse than the desktop). I am using the default packaged kernel and scripts. I run hdparm -t /dev/sda1 And I got around 96GB/s, which is expected. What else can I try to make it work better? EDIT: grzes:/home/ga# hdparm -i /dev/sda /dev/sda: Model=WDC WD15EARS-00Z5B1, FwRev=80.00A80, SerialNo=WD-WMAVU1362357 Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=50 BuffType=unknown, BuffSize=unknown, MaxMultSect=16, MultSect=16 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=2930277168 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 AdvancedPM=no WriteCache=enabled Drive conforms to: Unspecified: ATA/ATAPI-1,2,3,4,5,6,7 * signifies the current active mode EDIT2: Even my wife said "on this new computer I can't do anything when I copy the photos from the camera and its much worse than on the old one". So it must be serious. EDIT3: Updated to 2.6.32, but still no improvement EDIT4: I forgot to mention that the new disk is ext4, the old was ext3. EDIT5: Still not solved. I have a P43 ASUS P5QL-E board. Lines from dmesg that seem relevant: [ 0.370850] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 253) [ 0.370852] io scheduler noop registered [ 0.370853] io scheduler anticipatory registered [ 0.370854] io scheduler deadline registered [ 0.370876] io scheduler cfq registered (default) ... [ 0.908233] ata_piix 0000:00:1f.2: version 2.13 [ 0.908243] ata_piix 0000:00:1f.2: PCI INT B -> GSI 19 (level, low) -> IRQ 19 [ 0.908246] ata_piix 0000:00:1f.2: MAP [ P0 P2 P1 P3 ] [ 0.908275] ata_piix 0000:00:1f.2: setting latency timer to 64 [ 0.908316] scsi0 : ata_piix [ 0.908374] scsi1 : ata_piix [ 0.909180] ata1: SATA max UDMA/133 cmd 0xa000 ctl 0x9c00 bmdma 0x9480 irq 19 [ 0.909183] ata2: SATA max UDMA/133 cmd 0x9880 ctl 0x9800 bmdma 0x9488 irq 19 [ 0.909199] ata_piix 0000:00:1f.5: PCI INT B -> GSI 19 (level, low) -> IRQ 19 [ 0.909202] ata_piix 0000:00:1f.5: MAP [ P0 -- P1 -- ] [ 0.909228] ata_piix 0000:00:1f.5: setting latency timer to 64 [ 0.909279] scsi2 : ata_piix [ 0.909326] scsi3 : ata_piix [ 0.910021] ata3: SATA max UDMA/133 cmd 0xb000 ctl 0xac00 bmdma 0xa480 irq 19 [ 0.910024] ata4: SATA max UDMA/133 cmd 0xa880 ctl 0xa800 bmdma 0xa488 irq 19 [ 0.915575] FDC 0 is a post-1991 82077 ... [ 1.716062] ata1.00: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [ 1.716074] ata1.01: SATA link down (SStatus 0 SControl 300) [ 1.724318] ata1.00: ATA-8: WDC WD15EARS-00Z5B1, 80.00A80, max UDMA/133 [ 1.724322] ata1.00: 2930277168 sectors, multi 16: LBA48 NCQ (depth 0/32) [ 1.740339] ata1.00: configured for UDMA/133 [ 1.740428] scsi 0:0:0:0: Direct-Access ATA WDC WD15EARS-00Z 80.0 PQ: 0 ANSI: 5 [ 1.746788] scsi 6:0:0:0: CD-ROM ASUS DRW-1608P 1.17 PQ: 0 ANSI: 5 ... [ 1.925981] sd 0:0:0:0: [sda] 2930277168 512-byte logical blocks: (1.50 TB/1.36 TiB) [ 1.926005] sd 0:0:0:0: [sda] Write Protect is off [ 1.926007] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 1.926020] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 1.926092] sda:sr0: scsi3-mmc drive: 40x/40x writer cd/rw xa/form2 cdda tray [ 1.931106] Uniform CD-ROM driver Revision: 3.20 [ 1.931191] sr 6:0:0:0: Attached scsi CD-ROM sr0 ... [ 1.941936] sda1 sda2 sda3 sda4 < sda5 sda6 > [ 1.967691] sd 0:0:0:0: [sda] Attached SCSI disk [ 1.970938] sd 0:0:0:0: Attached scsi generic sg0 type 0 [ 1.970959] sr 6:0:0:0: Attached scsi generic sg1 type 5 ... [ 2.500086] EXT4-fs (sda3): mounted filesystem with ordered data mode ... [ 7.150468] EXT4-fs (sda6): mounted filesystem with ordered data mode

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• why nginx rewrite post request from /login to //login?

  - by jiangchengwu

  There is a if statement, which will rewrite url when the client is Android. Everything ok. But, something got strange. Nginx will write post request /login to //login, even if the block of if statement is bank. So I got a 404 page. As the jetty server only accept /login request. Server conf: location / { proxy_pass http://localhost:8785/; proxy_set_header Host $http_host; proxy_set_header Remote-Addr $http_remote_addr; proxy_set_header X-Real-IP $remote_addr; if ( $http_user_agent ~ Android ){ # rewrite something, been commented } } Debug info, origin log https://gist.github.com/3799021 ... 2012/09/28 16:29:49 [debug] 26416#0: *1 http script regex: "Android" 2012/09/28 16:29:49 [notice] 26416#0: *1 "Android" matches "Android/1.0", client: 106.187.97.22, server: ireedr.com, request: "POST /login HTTP/1.1", host: "ireedr.com" ... 2012/09/28 16:29:49 [debug] 26416#0: *1 http proxy header: "POST //login HTTP/1.0 Host: ireedr.com X-Real-IP: 106.187.97.22 Connection: close Accept-Encoding: identity, deflate, compress, gzip Accept: */* User-Agent: Android/1.0 " ... 2012/09/28 16:29:49 [debug] 26416#0: *1 HTTP/1.1 404 Not Found Server: nginx/1.2.1 Date: Fri, 28 Sep 2012 08:29:49 GMT Content-Type: text/html;charset=ISO-8859-1 Transfer-Encoding: chunked Connection: keep-alive Cache-Control: must-revalidate,no-cache,no-store Content-Encoding: gzip ... Only when I commented the block in the configration file: location / { proxy_pass http://localhost:8785/; proxy_set_header Host $http_host; proxy_set_header Remote-Addr $http_remote_addr; proxy_set_header X-Real-IP $remote_addr; #if ( $http_user_agent ~ Android ){ # #} } The client can get an 200 response. Debug info, origin log https://gist.github.com/3799023 ... "POST /login HTTP/1.0 Host: ireedr.com X-Real-IP: 106.187.97.22 Connection: close Accept-Encoding: identity, deflate, compress, gzip Accept: */* User-Agent: Android/1.0 " ... 2012/09/28 16:27:19 [debug] 26319#0: *1 HTTP/1.1 200 OK Server: nginx/1.2.1 Date: Fri, 28 Sep 2012 08:27:19 GMT Content-Type: application/json;charset=UTF-8 Content-Length: 17 Connection: keep-alive ... As the log: 2012/09/28 16:29:49 [notice] 26416#0: *1 "Android" matches "Android/1.0", client: 106.187.97.22, server: ireedr.com, request: "POST /login HTTP/1.1", host: "ireedr.com" 2012/09/28 16:29:49 [debug] 26416#0: *1 http script if 2012/09/28 16:29:49 [debug] 26416#0: *1 post rewrite phase: 4 2012/09/28 16:29:49 [debug] 26416#0: *1 generic phase: 5 2012/09/28 16:29:49 [debug] 26416#0: *1 generic phase: 6 2012/09/28 16:29:49 [debug] 26416#0: *1 generic phase: 7 2012/09/28 16:29:49 [debug] 26416#0: *1 access phase: 8 2012/09/28 16:29:49 [debug] 26416#0: *1 access phase: 9 2012/09/28 16:29:49 [debug] 26416#0: *1 access phase: 10 2012/09/28 16:29:49 [debug] 26416#0: *1 post access phase: 11 2012/09/28 16:29:49 [debug] 26416#0: *1 try files phase: 12 2012/09/28 16:29:49 [debug] 26416#0: *1 posix_memalign: 0000000001E798F0:4096 @16 2012/09/28 16:29:49 [debug] 26416#0: *1 http init upstream, client timer: 0 2012/09/28 16:29:49 [debug] 26416#0: *1 epoll add event: fd:13 op:3 ev:80000005 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: "Host: " 2012/09/28 16:29:49 [debug] 26416#0: *1 http script var: "ireedr.com" 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: " " 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: "" 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: "" 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: "X-Real-IP: " 2012/09/28 16:29:49 [debug] 26416#0: *1 http script var: "106.187.97.22" 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: " " 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: "Connection: close " 2012/09/28 16:29:49 [debug] 26416#0: *1 http proxy header: "Accept-Encoding: identity, deflate, compress, gzip" 2012/09/28 16:29:49 [debug] 26416#0: *1 http proxy header: "Accept: */*" 2012/09/28 16:29:49 [debug] 26416#0: *1 http proxy header: "User-Agent: Android/1.0" 2012/09/28 16:29:49 [debug] 26416#0: *1 http proxy header: "POST //login HTTP/1.0 Host: ireedr.com X-Real-IP: 106.187.97.22 Connection: close Accept-Encoding: identity, deflate, compress, gzip Accept: */* User-Agent: Android/1.0 " ... Maybe post rewrite phase had rewrite the request. Anybody can help me to solve this problem or know why nginx do that ? Much appreciated.

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• Dynamic JSON Parsing in .NET with JsonValue

  - by Rick Strahl

  So System.Json has been around for a while in Silverlight, but it's relatively new for the desktop .NET framework and now moving into the lime-light with the pending release of ASP.NET Web API which is bringing a ton of attention to server side JSON usage. The JsonValue, JsonObject and JsonArray objects are going to be pretty useful for Web API applications as they allow you dynamically create and parse JSON values without explicit .NET types to serialize from or into. But even more so I think JsonValue et al. are going to be very useful when consuming JSON APIs from various services. Yes I know C# is strongly typed, why in the world would you want to use dynamic values? So many times I've needed to retrieve a small morsel of information from a large service JSON response and rather than having to map the entire type structure of what that service returns, JsonValue actually allows me to cherry pick and only work with the values I'm interested in, without having to explicitly create everything up front. With JavaScriptSerializer or DataContractJsonSerializer you always need to have a strong type to de-serialize JSON data into. Wouldn't it be nice if no explicit type was required and you could just parse the JSON directly using a very easy to use object syntax? That's exactly what JsonValue, JsonObject and JsonArray accomplish using a JSON parser and some sweet use of dynamic sauce to make it easy to access in code. Creating JSON on the fly with JsonValue Let's start with creating JSON on the fly. It's super easy to create a dynamic object structure. JsonValue uses the dynamic  keyword extensively to make it intuitive to create object structures and turn them into JSON via dynamic object syntax. Here's an example of creating a music album structure with child songs using JsonValue:[TestMethod] public void JsonValueOutputTest() { // strong type instance var jsonObject = new JsonObject(); // dynamic expando instance you can add properties to dynamic album = jsonObject; album.AlbumName = "Dirty Deeds Done Dirt Cheap"; album.Artist = "AC/DC"; album.YearReleased = 1977; album.Songs = new JsonArray() as dynamic; dynamic song = new JsonObject(); song.SongName = "Dirty Deeds Done Dirt Cheap"; song.SongLength = "4:11"; album.Songs.Add(song); song = new JsonObject(); song.SongName = "Love at First Feel"; song.SongLength = "3:10"; album.Songs.Add(song); Console.WriteLine(album.ToString()); } This produces proper JSON just as you would expect: {"AlbumName":"Dirty Deeds Done Dirt Cheap","Artist":"AC\/DC","YearReleased":1977,"Songs":[{"SongName":"Dirty Deeds Done Dirt Cheap","SongLength":"4:11"},{"SongName":"Love at First Feel","SongLength":"3:10"}]} The important thing about this code is that there's no explicitly type that is used for holding the values to serialize to JSON. I am essentially creating this value structure on the fly by adding properties and then serialize it to JSON. This means this code can be entirely driven at runtime without compile time restraints of structure for the JSON output. Here I use JsonObject() to create a new object and immediately cast it to dynamic. JsonObject() is kind of similar in behavior to ExpandoObject in that it allows you to add properties by simply assigning to them. Internally, JsonValue/JsonObject these values are stored in pseudo collections of key value pairs that are exposed as properties through the DynamicObject functionality in .NET. The syntax gets a little tedious only if you need to create child objects or arrays that have to be explicitly defined first. Other than that the syntax looks like normal object access sytnax. Always remember though these values are dynamic - which means no Intellisense and no compiler type checking. It's up to you to ensure that the values you create are accessed consistently and without typos in your code. Note that you can also access the JsonValue instance directly and get access to the underlying type. This means you can assign properties by string, which can be useful for fully data driven JSON generation from other structures. Below you can see both styles of access next to each other:// strong type instance var jsonObject = new JsonObject(); // you can explicitly add values here jsonObject.Add("Entered", DateTime.Now); // expando style instance you can just 'use' properties dynamic album = jsonObject; album.AlbumName = "Dirty Deeds Done Dirt Cheap"; JsonValue internally stores properties keys and values in collections and you can iterate over them at runtime. You can also manipulate the collections if you need to to get the object structure to look exactly like you want. Again, if you've used ExpandoObject before JsonObject/Value are very similar in the behavior of the structure. Reading JSON strings into JsonValue The JsonValue structure supports importing JSON via the Parse() and Load() methods which can read JSON data from a string or various streams respectively. Essentially JsonValue includes the core JSON parsing to turn a JSON string into a collection of JsonValue objects that can be then referenced using familiar dynamic object syntax. Here's a simple example:[TestMethod] public void JsonValueParsingTest() { var jsonString = @"{""Name"":""Rick"",""Company"":""West Wind"",""Entered"":""2012-03-16T00:03:33.245-10:00""}"; dynamic json = JsonValue.Parse(jsonString); // values require casting string name = json.Name; string company = json.Company; DateTime entered = json.Entered; Assert.AreEqual(name, "Rick"); Assert.AreEqual(company, "West Wind"); } The JSON string represents an object with three properties which is parsed into a JsonValue object and cast to dynamic. Once cast to dynamic I can then go ahead and access the object using familiar object syntax. Note that the actual values - json.Name, json.Company, json.Entered - are actually of type JsonPrimitive and I have to assign them to their appropriate types first before I can do type comparisons. The dynamic properties will automatically cast to the right type expected as long as the compiler can resolve the type of the assignment or usage. The AreEqual() method oesn't as it expects two object instances and comparing json.Company to "West Wind" is comparing two different types (JsonPrimitive to String) which fails. So the intermediary assignment is required to make the test pass. The JSON structure can be much more complex than this simple example. Here's another example of an array of albums serialized to JSON and then parsed through with JsonValue():[TestMethod] public void JsonArrayParsingTest() { var jsonString = @"[ { ""Id"": ""b3ec4e5c"", ""AlbumName"": ""Dirty Deeds Done Dirt Cheap"", ""Artist"": ""AC/DC"", ""YearReleased"": 1977, ""Entered"": ""2012-03-16T00:13:12.2810521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/61kTaH-uZBL._AA115_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/gp/product/B00008BXJ4/ref=as_li_ss_tl?ie=UTF8&tag=westwindtechn-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B00008BXJ4"", ""Songs"": [ { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Dirty Deeds Done Dirt Cheap"", ""SongLength"": ""4:11"" }, { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Love at First Feel"", ""SongLength"": ""3:10"" }, { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Big Balls"", ""SongLength"": ""2:38"" } ] }, { ""Id"": ""67280fb8"", ""AlbumName"": ""Echoes, Silence, Patience & Grace"", ""Artist"": ""Foo Fighters"", ""YearReleased"": 2007, ""Entered"": ""2012-03-16T00:13:12.2810521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/41mtlesQPVL._SL500_AA280_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/gp/product/B000UFAURI/ref=as_li_ss_tl?ie=UTF8&tag=westwindtechn-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B000UFAURI"", ""Songs"": [ { ""AlbumId"": ""67280fb8"", ""SongName"": ""The Pretender"", ""SongLength"": ""4:29"" }, { ""AlbumId"": ""67280fb8"", ""SongName"": ""Let it Die"", ""SongLength"": ""4:05"" }, { ""AlbumId"": ""67280fb8"", ""SongName"": ""Erase/Replay"", ""SongLength"": ""4:13"" } ] }, { ""Id"": ""7b919432"", ""AlbumName"": ""End of the Silence"", ""Artist"": ""Henry Rollins Band"", ""YearReleased"": 1992, ""Entered"": ""2012-03-16T00:13:12.2800521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/51FO3rb1tuL._SL160_AA160_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/End-Silence-Rollins-Band/dp/B0000040OX/ref=sr_1_5?ie=UTF8&qid=1302232195&sr=8-5"", ""Songs"": [ { ""AlbumId"": ""7b919432"", ""SongName"": ""Low Self Opinion"", ""SongLength"": ""5:24"" }, { ""AlbumId"": ""7b919432"", ""SongName"": ""Grip"", ""SongLength"": ""4:51"" } ] } ]"; dynamic albums = JsonValue.Parse(jsonString); foreach (dynamic album in albums) { Console.WriteLine(album.AlbumName + " (" + album.YearReleased.ToString() + ")"); foreach (dynamic song in album.Songs) { Console.WriteLine("\t" + song.SongName ); } } Console.WriteLine(albums[0].AlbumName); Console.WriteLine(albums[0].Songs[1].SongName);}   It's pretty sweet how easy it becomes to parse even complex JSON and then just run through the object using object syntax, yet without an explicit type in the mix. In fact it looks and feels a lot like if you were using JavaScript to parse through this data, doesn't it? And that's the point…© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  Web Api  JSON   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Using LINQ Distinct: With an Example on ASP.NET MVC SelectListItem

  - by Joe Mayo

  One of the things that might be surprising in the LINQ Distinct standard query operator is that it doesn’t automatically work properly on custom classes. There are reasons for this, which I’ll explain shortly. The example I’ll use in this post focuses on pulling a unique list of names to load into a drop-down list. I’ll explain the sample application, show you typical first shot at Distinct, explain why it won’t work as you expect, and then demonstrate a solution to make Distinct work with any custom class. The technologies I’m using are  LINQ to Twitter, LINQ to Objects, Telerik Extensions for ASP.NET MVC, ASP.NET MVC 2, and Visual Studio 2010. The function of the example program is to show a list of people that I follow.  In Twitter API vernacular, these people are called “Friends”; though I’ve never met most of them in real life. This is part of the ubiquitous language of social networking, and Twitter in particular, so you’ll see my objects named accordingly. Where Distinct comes into play is because I want to have a drop-down list with the names of the friends appearing in the list. Some friends are quite verbose, which means I can’t just extract names from each tweet and populate the drop-down; otherwise, I would end up with many duplicate names. Therefore, Distinct is the appropriate operator to eliminate the extra entries from my friends who tend to be enthusiastic tweeters. The sample doesn’t do anything with the drop-down list and I leave that up to imagination for what it’s practical purpose could be; perhaps a filter for the list if I only want to see a certain person’s tweets or maybe a quick list that I plan to combine with a TextBox and Button to reply to a friend. When the program runs, you’ll need to authenticate with Twitter, because I’m using OAuth (DotNetOpenAuth), for authentication, and then you’ll see the drop-down list of names above the grid with the most recent tweets from friends. Here’s what the application looks like when it runs: As you can see, there is a drop-down list above the grid. The drop-down list is where most of the focus of this article will be. There is some description of the code before we talk about the Distinct operator, but we’ll get there soon. This is an ASP.NET MVC2 application, written with VS 2010. Here’s the View that produces this screen: <%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<TwitterFriendsViewModel>" %> <%@ Import Namespace="DistinctSelectList.Models" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">     Home Page </asp:Content><asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">     <fieldset>         <legend>Twitter Friends</legend>         <div>             <%= Html.DropDownListFor(                     twendVM => twendVM.FriendNames,                     Model.FriendNames,                     "<All Friends>") %>         </div>         <div>             <% Html.Telerik().Grid<TweetViewModel>(Model.Tweets)                    .Name("TwitterFriendsGrid")                    .Columns(cols =>                     {                         cols.Template(col =>                             { %>                                 <img src="<%= col.ImageUrl %>"                                      alt="<%= col.ScreenName %>" />                         <% });                         cols.Bound(col => col.ScreenName);                         cols.Bound(col => col.Tweet);                     })                    .Render(); %>         </div>     </fieldset> </asp:Content> As shown above, the Grid is from Telerik’s Extensions for ASP.NET MVC. The first column is a template that renders the user’s Avatar from a URL provided by the Twitter query. Both the Grid and DropDownListFor display properties that are collections from a TwitterFriendsViewModel class, shown below: using System.Collections.Generic; using System.Web.Mvc; namespace DistinctSelectList.Models { /// /// For finding friend info on screen /// public class TwitterFriendsViewModel { /// /// Display names of friends in drop-down list /// public List FriendNames { get; set; } /// /// Display tweets in grid /// public List Tweets { get; set; } } } I created the TwitterFreindsViewModel. The two Lists are what the View consumes to populate the DropDownListFor and Grid. Notice that FriendNames is a List of SelectListItem, which is an MVC class. Another custom class I created is the TweetViewModel (the type of the Tweets List), shown below: namespace DistinctSelectList.Models { /// /// Info on friend tweets /// public class TweetViewModel { /// /// User's avatar /// public string ImageUrl { get; set; } /// /// User's Twitter name /// public string ScreenName { get; set; } /// /// Text containing user's tweet /// public string Tweet { get; set; } } } The initial Twitter query returns much more information than we need for our purposes and this a special class for displaying info in the View.  Now you know about the View and how it’s constructed. Let’s look at the controller next. The controller for this demo performs authentication, data retrieval, data manipulation, and view selection. I’ll skip the description of the authentication because it’s a normal part of using OAuth with LINQ to Twitter. Instead, we’ll drill down and focus on the Distinct operator. However, I’ll show you the entire controller, below,  so that you can see how it all fits together: using System.Linq; using System.Web.Mvc; using DistinctSelectList.Models; using LinqToTwitter; namespace DistinctSelectList.Controllers { [HandleError] public class HomeController : Controller { private MvcOAuthAuthorization auth; private TwitterContext twitterCtx; /// /// Display a list of friends current tweets /// /// public ActionResult Index() { auth = new MvcOAuthAuthorization(InMemoryTokenManager.Instance, InMemoryTokenManager.AccessToken); string accessToken = auth.CompleteAuthorize(); if (accessToken != null) { InMemoryTokenManager.AccessToken = accessToken; } if (auth.CachedCredentialsAvailable) { auth.SignOn(); } else { return auth.BeginAuthorize(); } twitterCtx = new TwitterContext(auth); var friendTweets = (from tweet in twitterCtx.Status where tweet.Type == StatusType.Friends select new TweetViewModel { ImageUrl = tweet.User.ProfileImageUrl, ScreenName = tweet.User.Identifier.ScreenName, Tweet = tweet.Text }) .ToList(); var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct() .ToList(); var twendsVM = new TwitterFriendsViewModel { Tweets = friendTweets, FriendNames = friendNames }; return View(twendsVM); } public ActionResult About() { return View(); } } } The important part of the listing above are the LINQ to Twitter queries for friendTweets and friendNames. Both of these results are used in the subsequent population of the twendsVM instance that is passed to the view. Let’s dissect these two statements for clarification and focus on what is happening with Distinct. The query for friendTweets gets a list of the 20 most recent tweets (as specified by the Twitter API for friend queries) and performs a projection into the custom TweetViewModel class, repeated below for your convenience: var friendTweets = (from tweet in twitterCtx.Status where tweet.Type == StatusType.Friends select new TweetViewModel { ImageUrl = tweet.User.ProfileImageUrl, ScreenName = tweet.User.Identifier.ScreenName, Tweet = tweet.Text }) .ToList(); The LINQ to Twitter query above simplifies what we need to work with in the View and the reduces the amount of information we have to look at in subsequent queries. Given the friendTweets above, the next query performs another projection into an MVC SelectListItem, which is required for binding to the DropDownList.  This brings us to the focus of this blog post, writing a correct query that uses the Distinct operator. The query below uses LINQ to Objects, querying the friendTweets collection to get friendNames: var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct() .ToList(); The above implementation of Distinct seems normal, but it is deceptively incorrect. After running the query above, by executing the application, you’ll notice that the drop-down list contains many duplicates.  This will send you back to the code scratching your head, but there’s a reason why this happens. To understand the problem, we must examine how Distinct works in LINQ to Objects. Distinct has two overloads: one without parameters, as shown above, and another that takes a parameter of type IEqualityComparer<T>.  In the case above, no parameters, Distinct will call EqualityComparer<T>.Default behind the scenes to make comparisons as it iterates through the list. You don’t have problems with the built-in types, such as string, int, DateTime, etc, because they all implement IEquatable<T>. However, many .NET Framework classes, such as SelectListItem, don’t implement IEquatable<T>. So, what happens is that EqualityComparer<T>.Default results in a call to Object.Equals, which performs reference equality on reference type objects.  You don’t have this problem with value types because the default implementation of Object.Equals is bitwise equality. However, most of your projections that use Distinct are on classes, just like the SelectListItem used in this demo application. So, the reason why Distinct didn’t produce the results we wanted was because we used a type that doesn’t define its own equality and Distinct used the default reference equality. This resulted in all objects being included in the results because they are all separate instances in memory with unique references. As you might have guessed, the solution to the problem is to use the second overload of Distinct that accepts an IEqualityComparer<T> instance. If you were projecting into your own custom type, you could make that type implement IEqualityComparer<T>, but SelectListItem belongs to the .NET Framework Class Library.  Therefore, the solution is to create a custom type to implement IEqualityComparer<T>, as in the SelectListItemComparer class, shown below: using System.Collections.Generic; using System.Web.Mvc; namespace DistinctSelectList.Models { public class SelectListItemComparer : EqualityComparer { public override bool Equals(SelectListItem x, SelectListItem y) { return x.Value.Equals(y.Value); } public override int GetHashCode(SelectListItem obj) { return obj.Value.GetHashCode(); } } } The SelectListItemComparer class above doesn’t implement IEqualityComparer<SelectListItem>, but rather derives from EqualityComparer<SelectListItem>. Microsoft recommends this approach for consistency with the behavior of generic collection classes. However, if your custom type already derives from a base class, go ahead and implement IEqualityComparer<T>, which will still work. EqualityComparer is an abstract class, that implements IEqualityComparer<T> with Equals and GetHashCode abstract methods. For the purposes of this application, the SelectListItem.Value property is sufficient to determine if two items are equal.   Since SelectListItem.Value is type string, the code delegates equality to the string class. The code also delegates the GetHashCode operation to the string class.You might have other criteria in your own object and would need to define what it means for your object to be equal. Now that we have an IEqualityComparer<SelectListItem>, let’s fix the problem. The code below modifies the query where we want distinct values: var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct(new SelectListItemComparer()) .ToList(); Notice how the code above passes a new instance of SelectListItemComparer as the parameter to the Distinct operator. Now, when you run the application, the drop-down list will behave as you expect, showing only a unique set of names. In addition to Distinct, other LINQ Standard Query Operators have overloads that accept IEqualityComparer<T>’s, You can use the same techniques as shown here, with SelectListItemComparer, with those other operators as well. Now you know how to resolve problems with getting Distinct to work properly and also have a way to fix problems with other operators that require equality comparisons. @JoeMayo

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• C#/.NET Little Wonders: Use Cast() and TypeOf() to Change Sequence Type

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. We’ve seen how the Select() extension method lets you project a sequence from one type to a new type which is handy for getting just parts of items, or building new items.  But what happens when the items in the sequence are already the type you want, but the sequence itself is typed to an interface or super-type instead of the sub-type you need? For example, you may have a sequence of Rectangle stored in an IEnumerable<Shape> and want to consider it an IEnumerable<Rectangle> sequence instead.  Today we’ll look at two handy extension methods, Cast<TResult>() and OfType<TResult>() which help you with this task. Cast<TResult>() – Attempt to cast all items to type TResult So, the first thing we can do would be to attempt to create a sequence of TResult from every item in the source sequence.  Typically we’d do this if we had an IEnumerable<T> where we knew that every item was actually a TResult where TResult inherits/implements T. For example, assume the typical Shape example classes: 1: // abstract base class 2: public abstract class Shape { } 3:  4: // a basic rectangle 5: public class Rectangle : Shape 6: { 7: public int Widtgh { get; set; } 8: public int Height { get; set; } 9: } And let’s assume we have a sequence of Shape where every Shape is a Rectangle… 1: var shapes = new List<Shape> 2: { 3: new Rectangle { Width = 3, Height = 5 }, 4: new Rectangle { Width = 10, Height = 13 }, 5: // ... 6: }; To get the sequence of Shape as a sequence of Rectangle, of course, we could use a Select() clause, such as: 1: // select each Shape, cast it to Rectangle 2: var rectangles = shapes 3: .Select(s => (Rectangle)s) 4: .ToList(); But that’s a bit verbose, and fortunately there is already a facility built in and ready to use in the form of the Cast<TResult>() extension method: 1: // cast each item to Rectangle and store in a List<Rectangle> 2: var rectangles = shapes 3: .Cast<Rectangle>() 4: .ToList(); However, we should note that if anything in the list cannot be cast to a Rectangle, you will get an InvalidCastException thrown at runtime.  Thus, if our Shape sequence had a Circle in it, the call to Cast<Rectangle>() would have failed.  As such, you should only do this when you are reasonably sure of what the sequence actually contains (or are willing to handle an exception if you’re wrong). Another handy use of Cast<TResult>() is using it to convert an IEnumerable to an IEnumerable<T>.  If you look at the signature, you’ll see that the Cast<TResult>() extension method actually extends the older, object-based IEnumerable interface instead of the newer, generic IEnumerable<T>.  This is your gateway method for being able to use LINQ on older, non-generic sequences.  For example, consider the following: 1: // the older, non-generic collections are sequence of object 2: var shapes = new ArrayList 3: { 4: new Rectangle { Width = 3, Height = 13 }, 5: new Rectangle { Width = 10, Height = 20 }, 6: // ... 7: }; Since this is an older, object based collection, we cannot use the LINQ extension methods on it directly.  For example, if I wanted to query the Shape sequence for only those Rectangles whose Width is > 5, I can’t do this: 1: // compiler error, Where() operates on IEnumerable<T>, not IEnumerable 2: var bigRectangles = shapes.Where(r => r.Width > 5); However, I can use Cast<Rectangle>() to treat my ArrayList as an IEnumerable<Rectangle> and then do the query! 1: // ah, that’s better! 2: var bigRectangles = shapes.Cast<Rectangle>().Where(r => r.Width > 5); Or, if you prefer, in LINQ query expression syntax: 1: var bigRectangles = from s in shapes.Cast<Rectangle>() 2: where s.Width > 5 3: select s; One quick warning: Cast<TResult>() only attempts to cast, it won’t perform a cast conversion.  That is, consider this: 1: var intList = new List<int> { 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 }; 2:  3: // casting ints to longs, this should work, right? 4: var asLong = intList.Cast<long>().ToList(); Will the code above work?  No, you’ll get a InvalidCastException. Remember that Cast<TResult>() is an extension of IEnumerable, thus it is a sequence of object, which means that it will box every int as an object as it enumerates over it, and there is no cast conversion from object to long, and thus the cast fails.  In other words, a cast from int to long will succeed because there is a conversion from int to long.  But a cast from int to object to long will not, because you can only unbox an item by casting it to its exact type. For more information on why cast-converting boxed values doesn’t work, see this post on The Dangers of Casting Boxed Values (here). OfType<TResult>() – Filter sequence to only items of type TResult So, we’ve seen how we can use Cast<TResult>() to change the type of our sequence, when we expect all the items of the sequence to be of a specific type.  But what do we do when a sequence contains many different types, and we are only concerned with a subset of a given type? For example, what if a sequence of Shape contains Rectangle and Circle instances, and we just want to select all of the Rectangle instances?  Well, let’s say we had this sequence of Shape: 1: var shapes = new List<Shape> 2: { 3: new Rectangle { Width = 3, Height = 5 }, 4: new Rectangle { Width = 10, Height = 13 }, 5: new Circle { Radius = 10 }, 6: new Square { Side = 13 }, 7: // ... 8: }; Well, we could get the rectangles using Select(), like: 1: var onlyRectangles = shapes.Where(s => s is Rectangle).ToList(); But fortunately, an easier way has already been written for us in the form of the OfType<T>() extension method: 1: // returns only a sequence of the shapes that are Rectangles 2: var onlyRectangles = shapes.OfType<Rectangle>().ToList(); Now we have a sequence of only the Rectangles in the original sequence, we can also use this to chain other queries that depend on Rectangles, such as: 1: // select only Rectangles, then filter to only those more than 2: // 5 units wide... 3: var onlyBigRectangles = shapes.OfType<Rectangle>() 4: .Where(r => r.Width > 5) 5: .ToList(); The OfType<Rectangle>() will filter the sequence to only the items that are of type Rectangle (or a subclass of it), and that results in an IEnumerable<Rectangle>, we can then apply the other LINQ extension methods to query that list further. Just as Cast<TResult>() is an extension method on IEnumerable (and not IEnumerable<T>), the same is true for OfType<T>().  This means that you can use OfType<TResult>() on object-based collections as well. For example, given an ArrayList containing Shapes, as below: 1: // object-based collections are a sequence of object 2: var shapes = new ArrayList 3: { 4: new Rectangle { Width = 3, Height = 5 }, 5: new Rectangle { Width = 10, Height = 13 }, 6: new Circle { Radius = 10 }, 7: new Square { Side = 13 }, 8: // ... 9: }; We can use OfType<Rectangle> to filter the sequence to only Rectangle items (and subclasses), and then chain other LINQ expressions, since we will then be of type IEnumerable<Rectangle>: 1: // OfType() converts the sequence of object to a new sequence 2: // containing only Rectangle or sub-types of Rectangle. 3: var onlyBigRectangles = shapes.OfType<Rectangle>() 4: .Where(r => r.Width > 5) 5: .ToList(); Summary So now we’ve seen two different ways to get a sequence of a superclass or interface down to a more specific sequence of a subclass or implementation.  The Cast<TResult>() method casts every item in the source sequence to type TResult, and the OfType<TResult>() method selects only those items in the source sequence that are of type TResult. You can use these to downcast sequences, or adapt older types and sequences that only implement IEnumerable (such as DataTable, ArrayList, etc.). Technorati Tags: C#,CSharp,.NET,LINQ,Little Wonders,TypeOf,Cast,IEnumerable<T>

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• Automatically create bug resolution task using the TFS 2010 API

  - by Bob Hardister

  My customer requires bug resolution to be approved and tracked.  To minimize the overhead for developers I implemented a TFS 2010 server-side plug-in to automatically create a child resolution task for the bug when the “CCB” field is set to approved. The CCB field is a custom field.  I also added the story points field to the bug WIT for sizing purposes. Redundant tasks will not be created unless the bug title is changed or the prior task is closed. The program writes an audit trail to a log file visible in the TFS Admin Console Log view. Here’s the code. BugAutoTask.cs /* SPECIFICATION * When the CCB field on the bug is set to approved, create a child task where the task: * name = Resolve bug [ID] - [Title of bug] * assigned to = same as assigned to field on the bug * same area path * same iteration path * activity = Bug Resolution * original estimate = bug points * * The source code is used to build a dll (Ows.TeamFoundation.BugAutoTaskCreation.PlugIns.dll), * which needs to be copied to * C:\Program Files\Microsoft Team Foundation Server 2010\Application Tier\Web Services\bin\Plugins * on ALL TFS application-tier servers. * * Author: Bob Hardister. */ using System; using System.Collections.Generic; using System.IO; using System.Xml; using System.Text; using System.Diagnostics; using System.Linq; using Microsoft.TeamFoundation.Common; using Microsoft.TeamFoundation.Framework.Server; using Microsoft.TeamFoundation.WorkItemTracking.Client; using Microsoft.TeamFoundation.WorkItemTracking.Server; using Microsoft.TeamFoundation.Client; using System.Collections; namespace BugAutoTaskCreation { public class BugAutoTask : ISubscriber { public EventNotificationStatus ProcessEvent(TeamFoundationRequestContext requestContext, NotificationType notificationType, object notificationEventArgs, out int statusCode, out string statusMessage, out ExceptionPropertyCollection properties) { statusCode = 0; properties = null; statusMessage = String.Empty; // Error message for for tracing last code executed and optional fields string lastStep = "No field values found or set "; try { if ((notificationType == NotificationType.Notification) && (notificationEventArgs.GetType() == typeof(WorkItemChangedEvent))) { WorkItemChangedEvent workItemChange = (WorkItemChangedEvent)notificationEventArgs; // see ConnectToTFS() method below to select which TFS instance/collection // to connect to TfsTeamProjectCollection tfs = ConnectToTFS(); WorkItemStore wiStore = tfs.GetService<WorkItemStore>(); lastStep = lastStep + ": connection to TFS successful "; // Get the work item that was just changed by the user. WorkItem witem = wiStore.GetWorkItem(workItemChange.CoreFields.IntegerFields[0].NewValue); lastStep = lastStep + ": retrieved changed work item, ID:" + witem.Id + " "; // Filter for Bug work items only if (witem.Type.Name == "Bug") { // DEBUG lastStep = lastStep + ": changed work item is a bug "; // Filter for CCB (i.e. Baseline Status) field set to approved only bool BaselineStatusChange = false; if (workItemChange.ChangedFields != null) { ProcessBugRevision(ref lastStep, workItemChange, wiStore, ref witem, ref BaselineStatusChange); } } } } catch (Exception e) { Trace.WriteLine(e.Message); Logger log = new Logger(); log.WriteLineToLog(MsgLevel.Error, "Application error: " + lastStep + " - " + e.Message + " - " + e.InnerException); } statusCode = 1; statusMessage = "Bug Auto Task Evaluation Completed"; properties = null; return EventNotificationStatus.ActionApproved; } // PRIVATE METHODS private static void ProcessBugRevision(ref string lastStep, WorkItemChangedEvent workItemChange, WorkItemStore wiStore, ref WorkItem witem, ref bool BaselineStatusChange) { foreach (StringField field in workItemChange.ChangedFields.StringFields) { // DEBUG lastStep = lastStep + ": last changed field is - " + field.Name + " "; if (field.Name == "Baseline Status") { lastStep = lastStep + ": retrieved bug baseline status field value, bug ID:" + witem.Id + " "; BaselineStatusChange = (field.NewValue != field.OldValue); if ((BaselineStatusChange) && (field.NewValue == "Approved")) { // Instanciate logger Logger log = new Logger(); // *** Create resolution task for this bug *** // ******************************************* // Get the team project and selected field values of the bug work item Project teamProject = witem.Project; int bugID = witem.Id; string bugTitle = witem.Fields["System.Title"].Value.ToString(); string bugAssignedTo = witem.Fields["System.AssignedTo"].Value.ToString(); string bugAreaPath = witem.Fields["System.AreaPath"].Value.ToString(); string bugIterationPath = witem.Fields["System.IterationPath"].Value.ToString(); string bugChangedBy = witem.Fields["System.ChangedBy"].OriginalValue.ToString(); string bugTeamProject = witem.Project.Name; lastStep = lastStep + ": all mandatory bug field values found "; // Optional fields Field bugPoints = witem.Fields["Microsoft.VSTS.Scheduling.StoryPoints"]; if (bugPoints.Value != null) { lastStep = lastStep + ": all mandatory and optional bug field values found "; } // Initialize child resolution task title string childTaskTitle = "Resolve bug " + bugID + " - " + bugTitle; // At this point I can check if a resolution task (of the same name) // for the bug already exist // If so, do not create a new resolution task bool createResolutionTask = true; WorkItem parentBug = wiStore.GetWorkItem(bugID); WorkItemLinkCollection links = parentBug.WorkItemLinks; foreach (WorkItemLink wil in links) { if (wil.LinkTypeEnd.Name == "Child") { WorkItem childTask = wiStore.GetWorkItem(wil.TargetId); if ((childTask.Title == childTaskTitle) && (childTask.State != "Closed")) { createResolutionTask = false; log.WriteLineToLog(MsgLevel.Info, "Team project " + bugTeamProject + ": " + bugChangedBy + " - set the CCB field to \"Approved\" for bug, ID: " + bugID + ". Task not created as open one of the same name already exist, ID:" + childTask.Id); } } } if (createResolutionTask) { // Define the work item type of the new work item WorkItemTypeCollection workItemTypes = wiStore.Projects[teamProject.Name].WorkItemTypes; WorkItemType wiType = workItemTypes["Task"]; // Setup the new task and assign field values witem = new WorkItem(wiType); witem.Fields["System.Title"].Value = "Resolve bug " + bugID + " - " + bugTitle; witem.Fields["System.AssignedTo"].Value = bugAssignedTo; witem.Fields["System.AreaPath"].Value = bugAreaPath; witem.Fields["System.IterationPath"].Value = bugIterationPath; witem.Fields["Microsoft.VSTS.Common.Activity"].Value = "Bug Resolution"; lastStep = lastStep + ": all mandatory task field values set "; // Optional fields if (bugPoints.Value != null) { witem.Fields["Microsoft.VSTS.Scheduling.OriginalEstimate"].Value = bugPoints.Value; lastStep = lastStep + ": all mandatory and optional task field values set "; } // Check for validation errors before saving the new task and linking it to the bug ArrayList validationErrors = witem.Validate(); if (validationErrors.Count == 0) { witem.Save(); // Link the new task (child) to the bug (parent) var linkType = wiStore.WorkItemLinkTypes[CoreLinkTypeReferenceNames.Hierarchy]; // Fetch the work items to be linked var parentWorkItem = wiStore.GetWorkItem(bugID); int taskID = witem.Id; var childWorkItem = wiStore.GetWorkItem(taskID); // Add a new link to the parent relating the child and save it parentWorkItem.Links.Add(new WorkItemLink(linkType.ForwardEnd, childWorkItem.Id)); parentWorkItem.Save(); log.WriteLineToLog(MsgLevel.Info, "Team project " + bugTeamProject + ": " + bugChangedBy + " - set the CCB field to \"Approved\" for bug, ID:" + bugID + ", which automatically created child resolution task, ID:" + taskID); } else { log.WriteLineToLog(MsgLevel.Error, "Error in creating bug resolution child task for bug ID:" + bugID); foreach (Field taskField in validationErrors) { log.WriteLineToLog(MsgLevel.Error, " - Validation Error in task field: " + taskField.ReferenceName); } } } } } } } private TfsTeamProjectCollection ConnectToTFS() { // Connect to TFS string tfsUri = string.Empty; // Production TFS instance production collection tfsUri = @"xxxx"; // Production TFS instance admin collection //tfsUri = @"xxxxx"; // Local TFS testing instance default collection //tfsUri = @"xxxxx"; TfsTeamProjectCollection tfs = new TfsTeamProjectCollection(new System.Uri(tfsUri)); tfs.EnsureAuthenticated(); return tfs; } // HELPERS public string Name { get { return "Bug Auto Task Creation Event Handler"; } } public SubscriberPriority Priority { get { return SubscriberPriority.Normal; } } public enum MsgLevel { Info, Warning, Error }; public Type[] SubscribedTypes() { return new Type[1] { typeof(WorkItemChangedEvent) }; } } } Logger.cs using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.Text; using System.Windows.Forms; namespace BugAutoTaskCreation { class Logger { // fields private string _ApplicationDirectory = @"C:\ProgramData\Microsoft\Team Foundation\Server Configuration\Logs"; private string _LogFileName = @"\CFG_ACCT_AT_OWS_BugAutoTaskCreation.log"; private string _LogFile; private string _LogTimestamp = DateTime.Now.ToString("MM/dd/yyyy HH:mm:ss"); private string _MsgLevelText = string.Empty; // default constructor public Logger() { // check for a prior log file FileInfo logFile = new FileInfo(_ApplicationDirectory + _LogFileName); if (!logFile.Exists) { CreateNewLogFile(ref logFile); } } // properties public string ApplicationDirectory { get { return _ApplicationDirectory; } set { _ApplicationDirectory = value; } } public string LogFile { get { _LogFile = _ApplicationDirectory + _LogFileName; return _LogFile; } set { _LogFile = value; } } // PUBLIC METHODS public void WriteLineToLog(BugAutoTask.MsgLevel msgLevel, string logRecord) { try { // set msgLevel text if (msgLevel == BugAutoTask.MsgLevel.Info) { _MsgLevelText = "[Info @" + MsgTimeStamp() + "] "; } else if (msgLevel == BugAutoTask.MsgLevel.Warning) { _MsgLevelText = "[Warning @" + MsgTimeStamp() + "] "; } else if (msgLevel == BugAutoTask.MsgLevel.Error) { _MsgLevelText = "[Error @" + MsgTimeStamp() + "] "; } else { _MsgLevelText = "[Error: unsupported message level @" + MsgTimeStamp() + "] "; } // write a line to the log file StreamWriter logFile = new StreamWriter(_ApplicationDirectory + _LogFileName, true); logFile.WriteLine(_MsgLevelText + logRecord); logFile.Close(); } catch (Exception) { throw; } } // PRIVATE METHODS private void CreateNewLogFile(ref FileInfo logFile) { try { string logFilePath = logFile.FullName; // write the log file header _MsgLevelText = "[Info @" + MsgTimeStamp() + "] "; string cpu = string.Empty; if (Environment.Is64BitOperatingSystem) { cpu = " (x64)"; } StreamWriter newLog = new StreamWriter(logFilePath, false); newLog.Flush(); newLog.WriteLine(_MsgLevelText + "===================================================================="); newLog.WriteLine(_MsgLevelText + "Team Foundation Server Administration Log"); newLog.WriteLine(_MsgLevelText + "Version : " + "1.0.0 Author: Bob Hardister"); newLog.WriteLine(_MsgLevelText + "DateTime : " + _LogTimestamp); newLog.WriteLine(_MsgLevelText + "Type : " + "OWS Custom TFS API Plug-in"); newLog.WriteLine(_MsgLevelText + "Activity : " + "Bug Auto Task Creation for CCB Approved Bugs"); newLog.WriteLine(_MsgLevelText + "Area : " + "Build Explorer"); newLog.WriteLine(_MsgLevelText + "Assembly : " + "Ows.TeamFoundation.BugAutoTaskCreation.PlugIns.dll"); newLog.WriteLine(_MsgLevelText + "Location : " + @"C:\Program Files\Microsoft Team Foundation Server 2010\Application Tier\Web Services\bin\Plugins"); newLog.WriteLine(_MsgLevelText + "User : " + Environment.UserDomainName + @"\" + Environment.UserName); newLog.WriteLine(_MsgLevelText + "Machine : " + Environment.MachineName); newLog.WriteLine(_MsgLevelText + "System : " + Environment.OSVersion + cpu); newLog.WriteLine(_MsgLevelText + "===================================================================="); newLog.WriteLine(_MsgLevelText); newLog.Close(); } catch (Exception) { throw; } } private string MsgTimeStamp() { string msgTimestamp = string.Empty; return msgTimestamp = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss:fff"); } } }

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• Snake Game Help

  - by MuhammadA

  I am making a snake game and learning XNA at the same time. I have 3 classes : Game.cs, Snake.cs and Apple.cs My problem is more of a conceptual problem, I want to know which class is really responsible for ... detecting collision of snake head on apple/itself/wall? which class should increase the snakes speed, size? It seems to me that however much I try and put the snake stuff into snake.cs that game.cs has to know a lot about the snake, like : -- I want to increase the score depending on size of snake, the score variable is inside game.cs, which means now I have to ask the snake its size on every hit of the apple... seems a bit unclean all this highly coupled code. or -- I DO NOT want to place the apple under the snake... now the apple suddenly has to know about all the snake parts, my head hurts when I think of that. Maybe there should be some sort of AppleLayer.cs class that should know about the snake... Whats the best approach in such a simple scenario? Any tips welcome. Game.cs : using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; using Microsoft.Xna.Framework.Design; namespace Snakez { public enum CurrentGameState { Playing, Paused, NotPlaying } public class Game1 : Microsoft.Xna.Framework.Game { private GraphicsDeviceManager _graphics; private SpriteBatch _spriteBatch; private readonly Color _niceGreenColour = new Color(167, 255, 124); private KeyboardState _oldKeyboardState; private SpriteFont _scoreFont; private SoundEffect _biteSound, _crashSound; private Vector2 _scoreLocation = new Vector2(10, 10); private Apple _apple; private Snake _snake; private int _score = 0; private int _speed = 1; public Game1() { _graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { base.Initialize(); } /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { _spriteBatch = new SpriteBatch(GraphicsDevice); _scoreFont = Content.Load<SpriteFont>("Score"); _apple = new Apple(800, 480, Content.Load<Texture2D>("Apple")); _snake = new Snake(Content.Load<Texture2D>("BodyBlock")); _biteSound = Content.Load<SoundEffect>("Bite"); _crashSound = Content.Load<SoundEffect>("Crash"); } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { Content.Unload(); } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Update(GameTime gameTime) { KeyboardState newKeyboardState = Keyboard.GetState(); if (newKeyboardState.IsKeyDown(Keys.Escape)) { this.Exit(); // Allows the game to exit } else if (newKeyboardState.IsKeyDown(Keys.Up) && !_oldKeyboardState.IsKeyDown(Keys.Up)) { _snake.SetDirection(Direction.Up); } else if (newKeyboardState.IsKeyDown(Keys.Down) && !_oldKeyboardState.IsKeyDown(Keys.Down)) { _snake.SetDirection(Direction.Down); } else if (newKeyboardState.IsKeyDown(Keys.Left) && !_oldKeyboardState.IsKeyDown(Keys.Left)) { _snake.SetDirection(Direction.Left); } else if (newKeyboardState.IsKeyDown(Keys.Right) && !_oldKeyboardState.IsKeyDown(Keys.Right)) { _snake.SetDirection(Direction.Right); } _oldKeyboardState = newKeyboardState; _snake.Update(); if (_snake.IsEating(_apple)) { _biteSound.Play(); _score += 10; _apple.Place(); } base.Update(gameTime); } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(_niceGreenColour); float frameRate = 1 / (float)gameTime.ElapsedGameTime.TotalSeconds; _spriteBatch.Begin(); _spriteBatch.DrawString(_scoreFont, "Score : " + _score, _scoreLocation, Color.Red); _apple.Draw(_spriteBatch); _snake.Draw(_spriteBatch); _spriteBatch.End(); base.Draw(gameTime); } } } Snake.cs : using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework; namespace Snakez { public enum Direction { Up, Down, Left, Right } public class Snake { private List<Rectangle> _parts; private readonly Texture2D _bodyBlock; private readonly int _startX = 160; private readonly int _startY = 120; private int _moveDelay = 100; private DateTime _lastUpdatedAt; private Direction _direction; private Rectangle _lastTail; public Snake(Texture2D bodyBlock) { _bodyBlock = bodyBlock; _parts = new List<Rectangle>(); _parts.Add(new Rectangle(_startX, _startY, _bodyBlock.Width, _bodyBlock.Height)); _parts.Add(new Rectangle(_startX + bodyBlock.Width, _startY, _bodyBlock.Width, _bodyBlock.Height)); _parts.Add(new Rectangle(_startX + (bodyBlock.Width) * 2, _startY, _bodyBlock.Width, _bodyBlock.Height)); _parts.Add(new Rectangle(_startX + (bodyBlock.Width) * 3, _startY, _bodyBlock.Width, _bodyBlock.Height)); _direction = Direction.Right; _lastUpdatedAt = DateTime.Now; } public void Draw(SpriteBatch spriteBatch) { foreach (var p in _parts) { spriteBatch.Draw(_bodyBlock, new Vector2(p.X, p.Y), Color.White); } } public void Update() { if (DateTime.Now.Subtract(_lastUpdatedAt).TotalMilliseconds > _moveDelay) { //DateTime.Now.Ticks _lastTail = _parts.First(); _parts.Remove(_lastTail); /* add new head in right direction */ var lastHead = _parts.Last(); var newHead = new Rectangle(0, 0, _bodyBlock.Width, _bodyBlock.Height); switch (_direction) { case Direction.Up: newHead.X = lastHead.X; newHead.Y = lastHead.Y - _bodyBlock.Width; break; case Direction.Down: newHead.X = lastHead.X; newHead.Y = lastHead.Y + _bodyBlock.Width; break; case Direction.Left: newHead.X = lastHead.X - _bodyBlock.Width; newHead.Y = lastHead.Y; break; case Direction.Right: newHead.X = lastHead.X + _bodyBlock.Width; newHead.Y = lastHead.Y; break; } _parts.Add(newHead); _lastUpdatedAt = DateTime.Now; } } public void SetDirection(Direction newDirection) { if (_direction == Direction.Up && newDirection == Direction.Down) { return; } else if (_direction == Direction.Down && newDirection == Direction.Up) { return; } else if (_direction == Direction.Left && newDirection == Direction.Right) { return; } else if (_direction == Direction.Right && newDirection == Direction.Left) { return; } _direction = newDirection; } public bool IsEating(Apple apple) { if (_parts.Last().Intersects(apple.Location)) { GrowBiggerAndFaster(); return true; } return false; } private void GrowBiggerAndFaster() { _parts.Insert(0, _lastTail); _moveDelay -= (_moveDelay / 100)*2; } } } Apple.cs : using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework; namespace Snakez { public class Apple { private readonly int _maxWidth, _maxHeight; private readonly Texture2D _texture; private readonly Random random = new Random(); public Rectangle Location { get; private set; } public Apple(int screenWidth, int screenHeight, Texture2D texture) { _maxWidth = (screenWidth + 1) - texture.Width; _maxHeight = (screenHeight + 1) - texture.Height; _texture = texture; Place(); } public void Place() { Location = GetRandomLocation(_maxWidth, _maxHeight); } private Rectangle GetRandomLocation(int maxWidth, int maxHeight) { // x and y -- multiple of 20 int x = random.Next(1, maxWidth); var leftOver = x % 20; x = x - leftOver; int y = random.Next(1, maxHeight); leftOver = y % 20; y = y - leftOver; return new Rectangle(x, y, _texture.Width, _texture.Height); } public void Draw(SpriteBatch spriteBatch) { spriteBatch.Draw(_texture, Location, Color.White); } } }

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• NullReferenceException when changing skin/theme via Application.Current.Resources

  - by CoolCat

  I am writing an wpf application with multiple skins. The code to switch theme is as below: try { Application.Current.Resources.MergedDictionaries.Add( resource ); } catch( Exception ex ) { } The first time the code is called (to switch to a new theme), it is executed successfully; however, any subsequent calls to the same code would throw System.NullReferenceException. The way I set up my themes are similar to what described here: http://www.codewrecks.com/blog/index.php/2008/05/22/simple-skinnable-and-theme-management-in-wpf-user-interface/. Has anyone seen this error before? How do I go about debugging this since the exception is thrown else where? Any help is greatly appreciated. StackTrace: at System.Windows.EffectiveValueEntry.GetFlattenedEntry(RequestFlags requests) at System.Windows.DependencyObject.EvaluateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry newEntry, OperationType operationType) at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, OperationType operationType) at System.Windows.StyleHelper.ApplyStyleOrTemplateValue(FrameworkObject fo, DependencyProperty dp) at System.Windows.StyleHelper.InvalidateContainerDependents(DependencyObject container, FrugalStructList`1& exclusionContainerDependents, FrugalStructList`1& oldContainerDependents, FrugalStructList`1& newContainerDependents) at System.Windows.StyleHelper.DoStyleInvalidations(FrameworkElement fe, FrameworkContentElement fce, Style oldStyle, Style newStyle) at System.Windows.StyleHelper.UpdateStyleCache(FrameworkElement fe, FrameworkContentElement fce, Style oldStyle, Style newStyle, Style& styleCache) at System.Windows.FrameworkElement.OnStyleChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e) at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e) at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args) at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, OperationType operationType) at System.Windows.DependencyObject.InvalidateProperty(DependencyProperty dp) at System.Windows.FrameworkElement.UpdateStyleProperty() at System.Windows.TreeWalkHelper.InvalidateStyleAndReferences(DependencyObject d, ResourcesChangeInfo info, Boolean containsTypeOfKey) at System.Windows.TreeWalkHelper.OnResourcesChanged(DependencyObject d, ResourcesChangeInfo info, Boolean raiseResourceChangedEvent) at System.Windows.TreeWalkHelper.OnResourcesChangedCallback(DependencyObject d, ResourcesChangeInfo info) at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe) at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren) at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren) at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d) at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe) at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren) at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren) at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d) at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe) at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren) at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren) at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d) at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe) at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren) at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren) at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d) at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe) at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren) at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d) at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe) at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren) at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren) at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d) at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe) at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren) at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren) at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d) at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe) at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren) at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren) at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d) at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe) at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren) at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren) at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d) at System.Windows.DescendentsWalker`1._VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.VisitNode(FrameworkElement fe) at System.Windows.DescendentsWalker`1.VisitNode(DependencyObject d) at System.Windows.DescendentsWalker`1.WalkLogicalChildren(FrameworkElement feParent, FrameworkContentElement fceParent, IEnumerator logicalChildren) at System.Windows.DescendentsWalker`1.WalkFrameworkElementLogicalThenVisualChildren(FrameworkElement feParent, Boolean hasLogicalChildren) at System.Windows.DescendentsWalker`1.IterateChildren(DependencyObject d) at System.Windows.DescendentsWalker`1.StartWalk(DependencyObject startNode, Boolean skipStartNode) at System.Windows.TreeWalkHelper.InvalidateOnResourcesChange(FrameworkElement fe, FrameworkContentElement fce, ResourcesChangeInfo info) at System.Windows.Application.InvalidateResourceReferenceOnWindowCollection(WindowCollection wc, ResourcesChangeInfo info) at System.Windows.ResourceDictionary.NotifyOwners(ResourcesChangeInfo info) at System.Windows.ResourceDictionary.OnMergedDictionariesChanged(Object sender, NotifyCollectionChangedEventArgs e) at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e) at System.Collections.ObjectModel.ObservableCollection`1.InsertItem(Int32 index, T item) at System.Windows.ResourceDictionaryCollection.InsertItem(Int32 index, ResourceDictionary item) at System.Collections.ObjectModel.Collection`1.Add(T item)

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• Modern Java alternatives

  - by Ralph

  I'm not sure if stackoverflow is the best forum for this discussion. I have been a Java developer for 14 years and have written an enterprise-level (~500,000 line) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for the stackoverflow readerships' opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. If anyone has a suggestion for another JVM-based language that can be used for enterprise level development, please list it. Also, it is not my intent to start a flame war. Thanks, Ralph

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• Modern alternatives to Java

  - by Ralph

  I have been a Java developer for 14 years and have written an enterprise-level (~500 kloc) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. Are there other JVM-based languages that can be used for enterprise level development?

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• LinkedList Wrong Display(string builder)

  - by Chris

  Hello, The following program is a basic linked list divided in 3 classes. In the tester class (main) i add several numbers to the list (sorted). But insteed of getting the numbers as a result i get the result: LinkedList.LinkedList Is something wrong with the stringbuilder (the program was first in java where a string buffer was used, but that should be the same i think?) LinkedListTester.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace LinkedList { public class LinkedListTester { static void Main(string[] args) { LinkedList ll = new LinkedList(); ll.addDataSorted(5); ll.addDataSorted(7); ll.addDataSorted(13); ll.addDataSorted(1); ll.addDataSorted(17); ll.addDataSorted(8); Console.WriteLine(ll); } } }/LinkedList/ LinkedList.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace LinkedList { public class LinkedList { //toestand private LinkedListNode first; private LinkedListNode last; //gedrag public LinkedList() { first = null; last = null; } public void addDataInFront(int data) { first = new LinkedListNode(data, first); if (last == null){ last = first; } }/*addDataInFront*/ public void addDataToBack(int data) { if (first == null) { addDataInFront(data); } else { last.setNext(new LinkedListNode(data, null)); last = last.getNext(); } }/*addDataToBack*/ public void addDataSorted(int data) { if (first == null || first.getData() > data) { addDataInFront(data); } else { LinkedListNode currentNode = first; while (currentNode.getNext() != null && currentNode.getNext().getData() < data) { currentNode = currentNode.getNext(); } currentNode.setNext(new LinkedListNode(data, currentNode.getNext())); currentNode = currentNode.getNext(); if (currentNode.getNext() == null) { last = currentNode; } } }/*addDataSorted*/ public String toString() { StringBuilder Buf = new StringBuilder(); LinkedListNode currentNode = first; while (currentNode != null) { Buf.Append(currentNode.getData()); Buf.Append(' '); currentNode = currentNode.getNext(); } return Buf.ToString(); }/*toString*/ }/*LinkedList*/ }/LinkedList/ LinkedListNode: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace LinkedList { public class LinkedListNode { //toestand private int data; private LinkedListNode next; private LinkedListNode previous; //gedrag public LinkedListNode(int data, LinkedListNode next) { this.data = data; this.next = next; this.previous = null; } public LinkedListNode(int data, LinkedListNode next, LinkedListNode previous) { this.data = data; this.next = next; this.previous = previous; } public LinkedListNode getNext() { return next; } public LinkedListNode getPrevious() { return previous; } public void setNext(LinkedListNode next) { this.next = next; } public void setPrevious(LinkedListNode previous) { this.previous = previous; } public int getData() { return data; } }/*LinkedListNode*/ }/LinkedList/

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• One to many in nhibernate mapping problem

  - by chobo2

  Hi I have this using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Demo.Framework.Domain { public class UserEntity { public virtual Guid UserId { get; protected set; } } } using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace TDemo.Framework.Domain { public class Users : UserEntity { public virtual string OpenIdIdentifier { get; set; } public virtual string Email { get; set; } public virtual IList<Movie> Movies { get; set; } } } using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Demo.Framework.Domain { public class Movie { public virtual int MovieId { get; set; } public virtual Guid UserId { get; set; } // not sure if I should inherit UserEntity public virtual string Title { get; set; } public virtual DateTime ReleaseDate { get; set; } // in my ms sql 2008 database I want this to be just a Date type. Not sure how to do that. public virtual int Upc { get; set; } } } <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Demo.Framework" namespace="Demo.Framework.Domain"> <class name="Users"> <id name="UserId"> <generator class="guid.comb" /> </id> <property name="OpenIdIdentifier" not-null="true" /> <property name="Email" not-null="true" /> </class> <subclass name="Movie"> <list name="Movies" cascade="all-delete-orphan"> <key column="MovieId" /> <index column="MovieIndex" /> // not sure what index column is really. <one-to-many class="Movie"/> </list> </subclass> </hibernate-mapping> <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Demo.Framework" namespace="Demo.Framework.Domain"> <class name="Movie"> <id name="MovieId"> <generator class="native" /> </id> <property name="Title" not-null="true" /> <property name="ReleaseDate" not-null="true" type="Date" /> <property name="Upc" not-null="true" /> <property name="UserId" not-null="true" type="Guid"/> </class> </hibernate-mapping> I get this error 'extends' attribute is not found or is empty. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: NHibernate.MappingException: 'extends' attribute is not found or is empty. Source Error: Line 17: { Line 18: Line 19: var nhConfig = new Configuration().Configure(); Line 20: var sessionFactory = nhConfig.BuildSessionFactory(); Line 21:

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