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  • Any good idioms for error handling in straight C programs?

    - by Will Hartung
    Getting back in to some C work. Many of my functions look like this: int err = do_something(arg1, arg2, arg3, &result); With the intent the result gets populated by the function, and the return value is the status of the call. The darkside is you get something naive like this: int err = func1(...); if (!err) { err = func2(...); if (!err) { err = func3(...); } } return err; I could macro it I suppose: #define ERR(x) if (!err) { err = (x) } int err = 0; ERR(func1(...)); ERR(func2(...)); ERR(func3(...)); return err; But that only works if I'm chaining function calls, vs doing other work. Obviously Java, C#, C++ have exceptions that work very well for these kinds of things. I'm just curious what other folks do and how other folks do error handling in their C programs nowadays.

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  • ArchBeat Link-o-Rama for 2012-07-10

    - by Bob Rhubart
    Free Event Today: Virtual Developer Day: Oracle Fusion Development This free event—another in the ongoing series of OTN Virtual Developer Days—focuses on Oracle Fusion development, and features three session tracks plus hands-on labs. Agenda and session abstracts are available now so you can be ready for the live event when it kicks off today, July 10, 9am to 1pm PST / 12pm to 4pm EST / 1pm to 5pm BRT. Podcast: The Role of the Cloud Architect - Part 1/3 In part one of this three-part conversation, cloud architects Ron Batra (AT&T) and James Baty (Oracle) talk about how cloud computing is driving the supply-chaining of IT and the "democratization of the activity of architecture." Middleware and Cloud Computing Book | Tom Laszewski Cloud migration expert Tom Laszewski describes Middleware and Cloud Computing by Frank Munz as "one of only a couple books that really discuss AWS and Oracle in depth." Cloud computing moves from fad to foundation | David Linthicum "When enterprises make cloud computing work, they view the application of the technology as a trade secret of sorts, so there are no press releases or white papers," says David Linthicum. "Indeed, if you see one presentation around a successful cloud computing case study, you can bet you're not hearing about 100 more." Oracle Real-Time Decisions: Combined Likelihood Models | Lukas Vermeer Lukas Vermeer concludes his extensive series of posts on decision models with a look "an advanced approach to amalgamate models, taking us to a whole new level of predictive modeling and analytical insights; combination models predicting likelihoods using multiple child models." Running Oracle BPM 11g PS5 Worklist Task Flow and Human Task Form on Non-SOA Domain | Andrejus Baranovskis "With a standard setup, both the BPM worklist application and the Human task form run on the same SOA domain, where the BPM process is running," says Oracle ACE Director Andrejus Baranovskis. "While this work fine, this is not what we want in the development, test and production environment." BAM design pointers | Kavitha Srinivasan "When using EMS (Enterprise Message Source) as a BAM feed, the best practice is to use one EMS to write to one Data Object," says Oracle Fusion Middleware A-Team blogger Kavitha Srinivasan. "There is a possibility of collisions and duplicates when multiple EMS write to the same row of a DO at the same time." Changes in SOA Human Task Flow (Run-Time) for Fusion Applications | Jack Desai Oracle Fusion Middleware A-Team blogger Jack Desai shares a troubleshooting tip. Thought for the Day "A program which perfectly meets a lousy specification is a lousy program." — Cem Kaner Source: SoftwareQuotes.com

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  • How to refactor a Python “god class”?

    - by Zearin
    Problem I’m working on a Python project whose main class is a bit “God Object”. There are so friggin’ many attributes and methods! I want to refactor the class. So Far… For the first step, I want to do something relatively simple; but when I tried the most straightforward approach, it broke some tests and existing examples. Basically, the class has a loooong list of attributes—but I can clearly look over them and think, “These 5 attributes are related…These 8 are also related…and then there’s the rest.” getattr I basically just wanted to group the related attributes into a dict-like helper class. I had a feeling __getattr__ would be ideal for the job. So I moved the attributes to a separate class, and, sure enough, __getattr__ worked its magic perfectly well… At first. But then I tried running one of the examples. The example subclass tries to set one of these attributes directly (at the class level). But since the attribute was no longer “physically located” in the parent class, I got an error saying that the attribute did not exist. @property I then read up about the @property decorator. But then I also read that it creates problems for subclasses that want to do self.x = blah when x is a property of the parent class. Desired Have all client code continue to work using self.whatever, even if the parent’s whatever property is not “physically located” in the class (or instance) itself. Group related attributes into dict-like containers. Reduce the extreme noisiness of the code in the main class. For example, I don’t simply want to change this: larry = 2 curly = 'abcd' moe = self.doh() Into this: larry = something_else('larry') curly = something_else('curly') moe = yet_another_thing.moe() …because that’s still noisy. Although that successfully makes a simply attribute into something that can manage the data, the original had 3 variables and the tweaked version still has 3 variables. However, I would be fine with something like this: stooges = Stooges() And if a lookup for self.larry fails, something would check stooges and see if larry is there. (But it must also work if a subclass tries to do larry = 'blah' at the class level.) Summary Want to replace related groups of attributes in a parent class with a single attribute that stores all the data elsewhere Want to work with existing client code that uses (e.g.) larry = 'blah' at the class level Want to continue to allow subclasses to extend, override, and modify these refactored attributes without knowing anything has changed Is this possible? Or am I barking up the wrong tree?

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  • Export all SSIS packages from msdb using Powershell

    - by jamiet
    Have you ever wanted to dump all the SSIS packages stored in msdb out to files? Of course you have, who wouldn’t? Right? Well, at least one person does because this was the subject of a thread (save all ssis packages to file) on the SSIS forum earlier today. Some of you may have already figured out a way of doing this but for those that haven’t here is a nifty little script that will do it for you and it uses our favourite jack-of-all tools … Powershell!! Imagine I have the following package folder structure on my Integration Services server (i.e. in [msdb]): There are two packages in there called “20110111 Chaining Expression components” & “Package”, I want to export those two packages into a folder structure that mirrors that in [msdb]. Here is the Powershell script that will do that:Param($SQLInstance = "localhost") #####Add all the SQL goodies (including Invoke-Sqlcmd)##### add-pssnapin sqlserverprovidersnapin100 -ErrorAction SilentlyContinue add-pssnapin sqlservercmdletsnapin100 -ErrorAction SilentlyContinue cls $Packages = Invoke-Sqlcmd -MaxCharLength 10000000 -ServerInstance $SQLInstance -Query "WITH cte AS ( SELECT cast(foldername as varchar(max)) as folderpath, folderid FROM msdb..sysssispackagefolders WHERE parentfolderid = '00000000-0000-0000-0000-000000000000' UNION ALL SELECT cast(c.folderpath + '\' + f.foldername as varchar(max)), f.folderid FROM msdb..sysssispackagefolders f INNER JOIN cte c ON c.folderid = f.parentfolderid ) SELECT c.folderpath,p.name,CAST(CAST(packagedata AS VARBINARY(MAX)) AS VARCHAR(MAX)) as pkg FROM cte c INNER JOIN msdb..sysssispackages p ON c.folderid = p.folderid WHERE c.folderpath NOT LIKE 'Data Collector%'" Foreach ($pkg in $Packages) { $pkgName = $Pkg.name $folderPath = $Pkg.folderpath $fullfolderPath = "c:\temp\$folderPath\" if(!(test-path -path $fullfolderPath)) { mkdir $fullfolderPath | Out-Null } $pkg.pkg | Out-File -Force -encoding ascii -FilePath "$fullfolderPath\$pkgName.dtsx" } To run it simply change the “localhost” parameter of the server you want to connect to either by editing the script or passing it in when the script is executed. It will create the folder structure in C:\Temp (which you can also easily change if you so wish – just edit the script accordingly). Here’s the folder structure that it created for me: Notice how it is a mirror of the folder structure in [msdb]. Hope this is useful! @Jamiet UPDATE: THis post prompted Chad Miller to write a post describing his Powershell add-in that utilises a SSIS API to do exporting of packages. Go take a read here: http://sev17.com/2011/02/importing-and-exporting-ssis-packages-using-powershell/

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  • Export all SSIS packages from msdb using Powershell

    - by jamiet
    Have you ever wanted to dump all the SSIS packages stored in msdb out to files? Of course you have, who wouldn’t? Right? Well, at least one person does because this was the subject of a thread (save all ssis packages to file) on the SSIS forum earlier today. Some of you may have already figured out a way of doing this but for those that haven’t here is a nifty little script that will do it for you and it uses our favourite jack-of-all tools … Powershell!!   Imagine I have the following package folder structure on my Integration Services server (i.e. in [msdb]): There are two packages in there called “20110111 Chaining Expression components” & “Package”, I want to export those two packages into a folder structure that mirrors that in [msdb]. Here is the Powershell script that will do that:   Param($SQLInstance = "localhost") #####Add all the SQL goodies (including Invoke-Sqlcmd)##### add-pssnapin sqlserverprovidersnapin100 -ErrorAction SilentlyContinue add-pssnapin sqlservercmdletsnapin100 -ErrorAction SilentlyContinue cls $Packages = Invoke-Sqlcmd -MaxCharLength 10000000 -ServerInstance $SQLInstance -Query "WITH cte AS ( SELECT cast(foldername as varchar(max)) as folderpath, folderid FROM msdb..sysssispackagefolders WHERE parentfolderid = '00000000-0000-0000-0000-000000000000' UNION ALL SELECT cast(c.folderpath + '\' + f.foldername as varchar(max)), f.folderid FROM msdb..sysssispackagefolders f INNER JOIN cte c ON c.folderid = f.parentfolderid ) SELECT c.folderpath,p.name,CAST(CAST(packagedata AS VARBINARY(MAX)) AS VARCHAR(MAX)) as pkg FROM cte c INNER JOIN msdb..sysssispackages p ON c.folderid = p.folderid WHERE c.folderpath NOT LIKE 'Data Collector%'" Foreach ($pkg in $Packages) { $pkgName = $Pkg.name $folderPath = $Pkg.folderpath $fullfolderPath = "c:\temp\$folderPath\" if(!(test-path -path $fullfolderPath)) { mkdir $fullfolderPath | Out-Null } $pkg.pkg | Out-File -Force -encoding ascii -FilePath "$fullfolderPath\$pkgName.dtsx" }   To run it simply change the “localhost” parameter of the server you want to connect to either by editing the script or passing it in when the script is executed. It will create the folder structure in C:\Temp (which you can also easily change if you so wish – just edit the script accordingly). Here’s the folder structure that it created for me: Notice how it is a mirror of the folder structure in [msdb]. Hope this is useful! @Jamiet

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  • What's the best way to create a static utility class in python? Is using metaclasses code smell?

    - by rsimp
    Ok so I need to create a bunch of utility classes in python. Normally I would just use a simple module for this but I need to be able to inherit in order to share common code between them. The common code needs to reference the state of the module using it so simple imports wouldn't work well. I don't like singletons, and classes that use the classmethod decorator do not have proper support for python properties. One pattern I see used a lot is creating an internal python class prefixed with an underscore and creating a single instance which is then explicitly imported or set as the module itself. This is also used by fabric to create a common environment object (fabric.api.env). I've realized another way to accomplish this would be with metaclasses. For example: #util.py class MetaFooBase(type): @property def file_path(cls): raise NotImplementedError def inherited_method(cls): print cls.file_path #foo.py from util import * import env class MetaFoo(MetaFooBase): @property def file_path(cls): return env.base_path + "relative/path" def another_class_method(cls): pass class Foo(object): __metaclass__ = MetaFoo #client.py from foo import Foo file_path = Foo.file_path I like this approach better than the first pattern for a few reasons: First, instantiating Foo would be meaningless as it has no attributes or methods, which insures this class acts like a true single interface utility, unlike the first pattern which relies on the underscore convention to dissuade client code from creating more instances of the internal class. Second, sub-classing MetaFoo in a different module wouldn't be as awkward because I wouldn't be importing a class with an underscore which is inherently going against its private naming convention. Third, this seems to be the closest approximation to a static class that exists in python, as all the meta code applies only to the class and not to its instances. This is shown by the common convention of using cls instead of self in the class methods. As well, the base class inherits from type instead of object which would prevent users from trying to use it as a base for other non-static classes. It's implementation as a static class is also apparent when using it by the naming convention Foo, as opposed to foo, which denotes a static class method is being used. As much as I think this is a good fit, I feel that others might feel its not pythonic because its not a sanctioned use for metaclasses which should be avoided 99% of the time. I also find most python devs tend to shy away from metaclasses which might affect code reuse/maintainability. Is this code considered code smell in the python community? I ask because I'm creating a pypi package, and would like to do everything I can to increase adoption.

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  • Syncing client and server CRUD operations using json and php

    - by Justin
    I'm working on some code to sync the state of models between client (being a javascript application) and server. Often I end up writing redundant code to track the client and server objects so I can map the client supplied data to the server models. Below is some code I am thinking about implementing to help. What I don't like about the below code is that this method won't handle nested relationships very well, I would have to create multiple object trackers. One work around is for each server model after creating or loading, simply do $model->clientId = $clientId; IMO this is a nasty hack and I want to avoid it. Adding a setCientId method to all my model object would be another way to make it less hacky, but this seems like overkill to me. Really clientIds are only good for inserting/updating data in some scenarios. I could go with a decorator pattern but auto generating a proxy class seems a bit involved. I could use a generic proxy class that uses a __call function to allow for original object data to be accessed, but this seems wrong too. Any thoughts or comments? $clientData = '[{name: "Bob", action: "update", id: 1, clientId: 200}, {name:"Susan", action:"create", clientId: 131} ]'; $jsonObjs = json_decode($clientData); $objectTracker = new ObjectTracker(); $objectTracker->trackClientObjs($jsonObjs); $query = $this->em->createQuery("SELECT x FROM Application_Model_User x WHERE x.id IN (:ids)"); $query->setParameters("ids",$objectTracker->getClientSpecifiedServerIds()); $models = $query->getResults(); //Apply client data to server model foreach ($models as $model) { $clientModel = $objectTracker->getClientJsonObj($model->getId()); ... } //Create new models and persist foreach($objectTracker->getNewClientObjs() as $newClientObj) { $model = new Application_Model_User(); .... $em->persist($model); $objectTracker->trackServerObj($model); } $em->flush(); $resourceResponse = $objectTracker->createResourceResponse(); //Id mappings will be an associtave array representing server id resources with client side // id. //This method Dosen't seem to flexible if we want to return additional data with each resource... //Would have to modify the returned data structure, seems like tight coupling... //Ex return value: //[{clientId: 200, id:1} , {clientId: 131, id: 33}];

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  • Daisy-chainable DisplayPort Monitors

    - by thepurplepixel
    I am the proud new owner of a MacBook Pro with a mini-DisplayPort. My desk setup used to allow me to position the screen of my old MacBook beside an external monitor, essentially allowing dual-head. It was also advantageous that my old MBP and my external monitor had the same resolution, 1440x900. Now, I'm searching for a set of two monitors that I can use a HengeDock with. Unfortunately, the MacBook Pro suffers from having only one mini-DisplayPort. Looking up the spec for DisplayPort 1.2 (which the MBP supports), DisplayPort daisy chaining is supported. What I'm looking for is a monitor that has two DisplayPorts so I can daisy chain two monitors off the single mini-DisplayPort. What I don't want is a USB-based video solution. I need full acceleration on both monitors; an external video card won't cut it. I hope I don't have to wait a few years for these monitors to come out. TL;DR: I need two monitors with two DisplayPorts each that I can daisy-chain. Thanks!

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  • How to set up daisy-chained routers for separate sub-nets?

    - by joe
    This question seems to be similar to others, but I'll take a shot anyway. A client recently switched ISPs from TDS to Comcast Business Class. Before the switch, they had 5 static IP addresses assigned. Now they'll have a single IP address that will change whenever Comcast decides to do so. The issue is that this internet connection will be shared among two companies, both having (and wanting to keep) their own private subnets. Because TDS was supplying multiple IP addresses to the one location, this allowed me to put each router on the switch. Now, with Comcast, they only get one IP address, meaning there has to be a main router before the subnet routers. Luckily, the cable modem has a built-in router, which I would like to connect to each company's router, and still have DHCP enabled on all accounts. Question: What do I need to do to the subnet routers to keep them separate from each other, but still allow internet access from the main router. I would love to say "I tried this", and give you links, but everything I find on the internet only mentions daisy-chaining routers with DCHP disabled.

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  • How to chain GRUB2 for Ubuntu 10.04 from Truecrypt & its bootloader (multi boot alongside Windows XP partition)?

    - by Rob
    I want Truecrypt to ask for password for Windows XP as usual but with the standard [ESC] option, on selecting that, i.e via Escape key, I want it to find the grub for the (unencrypted) Ubuntu install. I've installed Windows XP on the 120Gb hard drive of a Toshiba NB100 netbook then partitioned to make room for Ubuntu 10.04 and installed that after the Windows XP install. When I encrypt Windows XP, Truecrypt will overwrite the grub entry in the master boot record (MBR), I believe (?) and I won't be able to choose between XP and Ubuntu anymore. So I need to restore it back. I've searched fairly extensively for answers on Ubuntu forums and elsewhere but have not yet found a complete answer that covers all eventualities, scenarios and error messages, or otherwise they talk of legacy GRUB and not GRUB2. Ubuntu 10.04 uses GRUB2. My setup: Partitions: Windows XP, NTFS (to be encrypted with Truecrypt), 40Gb /boot (Ext4, 1Gb) Ubuntu swap, 4Gb Ubuntu / (root) - main filesystem (20gb) NTFS share, 55Gb I know that the Truecrypt boot loader replaces the GRUB when boot up because I've already tried it on another laptop. I want boot loader screen to look something like the usual: Truecrypt Enter password: (or [ESC] to skip) password is for WindowsXP and on pressing [ESC] for it to find the Ubuntu grub to boot from Thanks in advance for your help. The key area of the problem is how to instruct Truecrypt when escape key is pressed, and how the Grub/Ubuntu can be made visible to the truecrypt bootloader to find it, when the esc key is pressed. Also knowing as chaining.

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  • Capturing and Transforming ASP.NET Output with Response.Filter

    - by Rick Strahl
    During one of my Handlers and Modules session at DevConnections this week one of the attendees asked a question that I didn’t have an immediate answer for. Basically he wanted to capture response output completely and then apply some filtering to the output – effectively injecting some additional content into the page AFTER the page had completely rendered. Specifically the output should be captured from anywhere – not just a page and have this code injected into the page. Some time ago I posted some code that allows you to capture ASP.NET Page output by overriding the Render() method, capturing the HtmlTextWriter() and reading its content, modifying the rendered data as text then writing it back out. I’ve actually used this approach on a few occasions and it works fine for ASP.NET pages. But this obviously won’t work outside of the Page class environment and it’s not really generic – you have to create a custom page class in order to handle the output capture. [updated 11/16/2009 – updated ResponseFilterStream implementation and a few additional notes based on comments] Enter Response.Filter However, ASP.NET includes a Response.Filter which can be used – well to filter output. Basically Response.Filter is a stream through which the OutputStream is piped back to the Web Server (indirectly). As content is written into the Response object, the filter stream receives the appropriate Stream commands like Write, Flush and Close as well as read operations although for a Response.Filter that’s uncommon to be hit. The Response.Filter can be programmatically replaced at runtime which allows you to effectively intercept all output generation that runs through ASP.NET. A common Example: Dynamic GZip Encoding A rather common use of Response.Filter hooking up code based, dynamic  GZip compression for requests which is dead simple by applying a GZipStream (or DeflateStream) to Response.Filter. The following generic routines can be used very easily to detect GZip capability of the client and compress response output with a single line of code and a couple of library helper routines: WebUtils.GZipEncodePage(); which is handled with a few lines of reusable code and a couple of static helper methods: /// <summary> ///Sets up the current page or handler to use GZip through a Response.Filter ///IMPORTANT:  ///You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() {     HttpResponse Response = HttpContext.Current.Response;     if(IsGZipSupported())     {         stringAcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"];         if(AcceptEncoding.Contains("deflate"))         {             Response.Filter = newSystem.IO.Compression.DeflateStream(Response.Filter,                                        System.IO.Compression.CompressionMode.Compress);             Response.AppendHeader("Content-Encoding", "deflate");         }         else        {             Response.Filter = newSystem.IO.Compression.GZipStream(Response.Filter,                                       System.IO.Compression.CompressionMode.Compress);             Response.AppendHeader("Content-Encoding", "gzip");                            }     }     // Allow proxy servers to cache encoded and unencoded versions separately    Response.AppendHeader("Vary", "Content-Encoding"); } /// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } GZipStream and DeflateStream are streams that are assigned to Response.Filter and by doing so apply the appropriate compression on the active Response. Response.Filter content is chunked So to implement a Response.Filter effectively requires only that you implement a custom stream and handle the Write() method to capture Response output as it’s written. At first blush this seems very simple – you capture the output in Write, transform it and write out the transformed content in one pass. And that indeed works for small amounts of content. But you see, the problem is that output is written in small buffer chunks (a little less than 16k it appears) rather than just a single Write() statement into the stream, which makes perfect sense for ASP.NET to stream data back to IIS in smaller chunks to minimize memory usage en route. Unfortunately this also makes it a more difficult to implement any filtering routines since you don’t directly get access to all of the response content which is problematic especially if those filtering routines require you to look at the ENTIRE response in order to transform or capture the output as is needed for the solution the gentleman in my session asked for. So in order to address this a slightly different approach is required that basically captures all the Write() buffers passed into a cached stream and then making the stream available only when it’s complete and ready to be flushed. As I was thinking about the implementation I also started thinking about the few instances when I’ve used Response.Filter implementations. Each time I had to create a new Stream subclass and create my custom functionality but in the end each implementation did the same thing – capturing output and transforming it. I thought there should be an easier way to do this by creating a re-usable Stream class that can handle stream transformations that are common to Response.Filter implementations. Creating a semi-generic Response Filter Stream Class What I ended up with is a ResponseFilterStream class that provides a handful of Events that allow you to capture and/or transform Response content. The class implements a subclass of Stream and then overrides Write() and Flush() to handle capturing and transformation operations. By exposing events it’s easy to hook up capture or transformation operations via single focused methods. ResponseFilterStream exposes the following events: CaptureStream, CaptureString Captures the output only and provides either a MemoryStream or String with the final page output. Capture is hooked to the Flush() operation of the stream. TransformStream, TransformString Allows you to transform the complete response output with events that receive a MemoryStream or String respectively and can you modify the output then return it back as a return value. The transformed output is then written back out in a single chunk to the response output stream. These events capture all output internally first then write the entire buffer into the response. TransformWrite, TransformWriteString Allows you to transform the Response data as it is written in its original chunk size in the Stream’s Write() method. Unlike TransformStream/TransformString which operate on the complete output, these events only see the current chunk of data written. This is more efficient as there’s no caching involved, but can cause problems due to searched content splitting over multiple chunks. Using this implementation, creating a custom Response.Filter transformation becomes as simple as the following code. To hook up the Response.Filter using the MemoryStream version event: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformStream += filter_TransformStream; Response.Filter = filter; and the event handler to do the transformation: MemoryStream filter_TransformStream(MemoryStream ms) { Encoding encoding = HttpContext.Current.Response.ContentEncoding; string output = encoding.GetString(ms.ToArray()); output = FixPaths(output); ms = new MemoryStream(output.Length); byte[] buffer = encoding.GetBytes(output); ms.Write(buffer,0,buffer.Length); return ms; } private string FixPaths(string output) { string path = HttpContext.Current.Request.ApplicationPath; // override root path wonkiness if (path == "/") path = ""; output = output.Replace("\"~/", "\"" + path + "/").Replace("'~/", "'" + path + "/"); return output; } The idea of the event handler is that you can do whatever you want to the stream and return back a stream – either the same one that’s been modified or a brand new one – which is then sent back to as the final response. The above code can be simplified even more by using the string version events which handle the stream to string conversions for you: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; and the event handler to do the transformation calling the same FixPaths method shown above: string filter_TransformString(string output) { return FixPaths(output); } The events for capturing output and capturing and transforming chunks work in a very similar way. By using events to handle the transformations ResponseFilterStream becomes a reusable component and we don’t have to create a new stream class or subclass an existing Stream based classed. By the way, the example used here is kind of a cool trick which transforms “~/” expressions inside of the final generated HTML output – even in plain HTML controls not HTML controls – and transforms them into the appropriate application relative path in the same way that ResolveUrl would do. So you can write plain old HTML like this: <a href=”~/default.aspx”>Home</a>  and have it turned into: <a href=”/myVirtual/default.aspx”>Home</a>  without having to use an ASP.NET control like Hyperlink or Image or having to constantly use: <img src=”<%= ResolveUrl(“~/images/home.gif”) %>” /> in MVC applications (which frankly is one of the most annoying things about MVC especially given the path hell that extension-less and endpoint-less URLs impose). I can’t take credit for this idea. While discussing the Response.Filter issues on Twitter a hint from Dylan Beattie who pointed me at one of his examples which does something similar. I thought the idea was cool enough to use an example for future demos of Response.Filter functionality in ASP.NET next I time I do the Modules and Handlers talk (which was great fun BTW). How practical this is is debatable however since there’s definitely some overhead to using a Response.Filter in general and especially on one that caches the output and the re-writes it later. Make sure to test for performance anytime you use Response.Filter hookup and make sure it' doesn’t end up killing perf on you. You’ve been warned :-}. How does ResponseFilterStream work? The big win of this implementation IMHO is that it’s a reusable  component – so for implementation there’s no new class, no subclassing – you simply attach to an event to implement an event handler method with a straight forward signature to retrieve the stream or string you’re interested in. The implementation is based on a subclass of Stream as is required in order to handle the Response.Filter requirements. What’s different than other implementations I’ve seen in various places is that it supports capturing output as a whole to allow retrieving the full response output for capture or modification. The exception are the TransformWrite and TransformWrite events which operate only active chunk of data written by the Response. For captured output, the Write() method captures output into an internal MemoryStream that is cached until writing is complete. So Write() is called when ASP.NET writes to the Response stream, but the filter doesn’t pass on the Write immediately to the filter’s internal stream. The data is cached and only when the Flush() method is called to finalize the Stream’s output do we actually send the cached stream off for transformation (if the events are hooked up) and THEN finally write out the returned content in one big chunk. Here’s the implementation of ResponseFilterStream: /// <summary> /// A semi-generic Stream implementation for Response.Filter with /// an event interface for handling Content transformations via /// Stream or String. /// <remarks> /// Use with care for large output as this implementation copies /// the output into a memory stream and so increases memory usage. /// </remarks> /// </summary> public class ResponseFilterStream : Stream { /// <summary> /// The original stream /// </summary> Stream _stream; /// <summary> /// Current position in the original stream /// </summary> long _position; /// <summary> /// Stream that original content is read into /// and then passed to TransformStream function /// </summary> MemoryStream _cacheStream = new MemoryStream(5000); /// <summary> /// Internal pointer that that keeps track of the size /// of the cacheStream /// </summary> int _cachePointer = 0; /// <summary> /// /// </summary> /// <param name="responseStream"></param> public ResponseFilterStream(Stream responseStream) { _stream = responseStream; } /// <summary> /// Determines whether the stream is captured /// </summary> private bool IsCaptured { get { if (CaptureStream != null || CaptureString != null || TransformStream != null || TransformString != null) return true; return false; } } /// <summary> /// Determines whether the Write method is outputting data immediately /// or delaying output until Flush() is fired. /// </summary> private bool IsOutputDelayed { get { if (TransformStream != null || TransformString != null) return true; return false; } } /// <summary> /// Event that captures Response output and makes it available /// as a MemoryStream instance. Output is captured but won't /// affect Response output. /// </summary> public event Action<MemoryStream> CaptureStream; /// <summary> /// Event that captures Response output and makes it available /// as a string. Output is captured but won't affect Response output. /// </summary> public event Action<string> CaptureString; /// <summary> /// Event that allows you transform the stream as each chunk of /// the output is written in the Write() operation of the stream. /// This means that that it's possible/likely that the input /// buffer will not contain the full response output but only /// one of potentially many chunks. /// /// This event is called as part of the filter stream's Write() /// operation. /// </summary> public event Func<byte[], byte[]> TransformWrite; /// <summary> /// Event that allows you to transform the response stream as /// each chunk of bytep[] output is written during the stream's write /// operation. This means it's possibly/likely that the string /// passed to the handler only contains a portion of the full /// output. Typical buffer chunks are around 16k a piece. /// /// This event is called as part of the stream's Write operation. /// </summary> public event Func<string, string> TransformWriteString; /// <summary> /// This event allows capturing and transformation of the entire /// output stream by caching all write operations and delaying final /// response output until Flush() is called on the stream. /// </summary> public event Func<MemoryStream, MemoryStream> TransformStream; /// <summary> /// Event that can be hooked up to handle Response.Filter /// Transformation. Passed a string that you can modify and /// return back as a return value. The modified content /// will become the final output. /// </summary> public event Func<string, string> TransformString; protected virtual void OnCaptureStream(MemoryStream ms) { if (CaptureStream != null) CaptureStream(ms); } private void OnCaptureStringInternal(MemoryStream ms) { if (CaptureString != null) { string content = HttpContext.Current.Response.ContentEncoding.GetString(ms.ToArray()); OnCaptureString(content); } } protected virtual void OnCaptureString(string output) { if (CaptureString != null) CaptureString(output); } protected virtual byte[] OnTransformWrite(byte[] buffer) { if (TransformWrite != null) return TransformWrite(buffer); return buffer; } private byte[] OnTransformWriteStringInternal(byte[] buffer) { Encoding encoding = HttpContext.Current.Response.ContentEncoding; string output = OnTransformWriteString(encoding.GetString(buffer)); return encoding.GetBytes(output); } private string OnTransformWriteString(string value) { if (TransformWriteString != null) return TransformWriteString(value); return value; } protected virtual MemoryStream OnTransformCompleteStream(MemoryStream ms) { if (TransformStream != null) return TransformStream(ms); return ms; } /// <summary> /// Allows transforming of strings /// /// Note this handler is internal and not meant to be overridden /// as the TransformString Event has to be hooked up in order /// for this handler to even fire to avoid the overhead of string /// conversion on every pass through. /// </summary> /// <param name="responseText"></param> /// <returns></returns> private string OnTransformCompleteString(string responseText) { if (TransformString != null) TransformString(responseText); return responseText; } /// <summary> /// Wrapper method form OnTransformString that handles /// stream to string and vice versa conversions /// </summary> /// <param name="ms"></param> /// <returns></returns> internal MemoryStream OnTransformCompleteStringInternal(MemoryStream ms) { if (TransformString == null) return ms; //string content = ms.GetAsString(); string content = HttpContext.Current.Response.ContentEncoding.GetString(ms.ToArray()); content = TransformString(content); byte[] buffer = HttpContext.Current.Response.ContentEncoding.GetBytes(content); ms = new MemoryStream(); ms.Write(buffer, 0, buffer.Length); //ms.WriteString(content); return ms; } /// <summary> /// /// </summary> public override bool CanRead { get { return true; } } public override bool CanSeek { get { return true; } } /// <summary> /// /// </summary> public override bool CanWrite { get { return true; } } /// <summary> /// /// </summary> public override long Length { get { return 0; } } /// <summary> /// /// </summary> public override long Position { get { return _position; } set { _position = value; } } /// <summary> /// /// </summary> /// <param name="offset"></param> /// <param name="direction"></param> /// <returns></returns> public override long Seek(long offset, System.IO.SeekOrigin direction) { return _stream.Seek(offset, direction); } /// <summary> /// /// </summary> /// <param name="length"></param> public override void SetLength(long length) { _stream.SetLength(length); } /// <summary> /// /// </summary> public override void Close() { _stream.Close(); } /// <summary> /// Override flush by writing out the cached stream data /// </summary> public override void Flush() { if (IsCaptured && _cacheStream.Length > 0) { // Check for transform implementations _cacheStream = OnTransformCompleteStream(_cacheStream); _cacheStream = OnTransformCompleteStringInternal(_cacheStream); OnCaptureStream(_cacheStream); OnCaptureStringInternal(_cacheStream); // write the stream back out if output was delayed if (IsOutputDelayed) _stream.Write(_cacheStream.ToArray(), 0, (int)_cacheStream.Length); // Clear the cache once we've written it out _cacheStream.SetLength(0); } // default flush behavior _stream.Flush(); } /// <summary> /// /// </summary> /// <param name="buffer"></param> /// <param name="offset"></param> /// <param name="count"></param> /// <returns></returns> public override int Read(byte[] buffer, int offset, int count) { return _stream.Read(buffer, offset, count); } /// <summary> /// Overriden to capture output written by ASP.NET and captured /// into a cached stream that is written out later when Flush() /// is called. /// </summary> /// <param name="buffer"></param> /// <param name="offset"></param> /// <param name="count"></param> public override void Write(byte[] buffer, int offset, int count) { if ( IsCaptured ) { // copy to holding buffer only - we'll write out later _cacheStream.Write(buffer, 0, count); _cachePointer += count; } // just transform this buffer if (TransformWrite != null) buffer = OnTransformWrite(buffer); if (TransformWriteString != null) buffer = OnTransformWriteStringInternal(buffer); if (!IsOutputDelayed) _stream.Write(buffer, offset, buffer.Length); } } The key features are the events and corresponding OnXXX methods that handle the event hookups, and the Write() and Flush() methods of the stream implementation. All the rest of the members tend to be plain jane passthrough stream implementation code without much consequence. I do love the way Action<t> and Func<T> make it so easy to create the event signatures for the various events – sweet. A few Things to consider Performance Response.Filter is not great for performance in general as it adds another layer of indirection to the ASP.NET output pipeline, and this implementation in particular adds a memory hit as it basically duplicates the response output into the cached memory stream which is necessary since you may have to look at the entire response. If you have large pages in particular this can cause potentially serious memory pressure in your server application. So be careful of wholesale adoption of this (or other) Response.Filters. Make sure to do some performance testing to ensure it’s not killing your app’s performance. Response.Filter works everywhere A few questions came up in comments and discussion as to capturing ALL output hitting the site and – yes you can definitely do that by assigning a Response.Filter inside of a module. If you do this however you’ll want to be very careful and decide which content you actually want to capture especially in IIS 7 which passes ALL content – including static images/CSS etc. through the ASP.NET pipeline. So it is important to filter only on what you’re looking for – like the page extension or maybe more effectively the Response.ContentType. Response.Filter Chaining Originally I thought that filter chaining doesn’t work at all due to a bug in the stream implementation code. But it’s quite possible to assign multiple filters to the Response.Filter property. So the following actually works to both compress the output and apply the transformed content: WebUtils.GZipEncodePage(); ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; However the following does not work resulting in invalid content encoding errors: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; WebUtils.GZipEncodePage(); In other words multiple Response filters can work together but it depends entirely on the implementation whether they can be chained or in which order they can be chained. In this case running the GZip/Deflate stream filters apparently relies on the original content length of the output and chokes when the content is modified. But if attaching the compression first it works fine as unintuitive as that may seem. Resources Download example code Capture Output from ASP.NET Pages © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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  • Knockout.js - Filtering, Sorting, and Paging

    - by jtimperley
    Originally posted on: http://geekswithblogs.net/jtimperley/archive/2013/07/28/knockout.js---filtering-sorting-and-paging.aspxKnockout.js is fantastic! Maybe I missed it but it appears to be missing flexible filtering, sorting, and pagination of its grids. This is a summary of my attempt at creating this functionality which has been working out amazingly well for my purposes. Before you continue, this post is not intended to teach you the basics of Knockout. They have already created a fantastic tutorial for this purpose. You'd be wise to review this before you continue. http://learn.knockoutjs.com/ Please view the full source code and functional example on jsFiddle. Below you will find a brief explanation of some of the components. http://jsfiddle.net/JTimperley/pyCTN/13/ First we need to create a model to represent our records. This model is a simple container with defined and guaranteed members. function CustomerModel(data) { if (!data) { data = {}; } var self = this; self.id = data.id; self.name = data.name; self.status = data.status; } Next we need a model to represent the page as a whole with an array of the previously defined records. I have intentionally overlooked the filtering and sorting options for now. Note how the filtering, sorting, and pagination are chained together to accomplish all three goals. This strategy allows each of these pieces to be used selectively based on the page's needs. If you only need sorting, just sort, etc. function CustomerPageModel(data) { if (!data) { data = {}; } var self = this; self.customers = ExtractModels(self, data.customers, CustomerModel); var filters = […]; var sortOptions = […]; self.filter = new FilterModel(filters, self.customers); self.sorter = new SorterModel(sortOptions, self.filter.filteredRecords); self.pager = new PagerModel(self.sorter.orderedRecords); } The code currently supports text box and drop down filters. Text box filters require defining the current 'Value' and the 'RecordValue' function to retrieve the filterable value from the provided record. Drop downs allow defining all possible values, the current option, and the 'RecordValue' as before. Once defining these filters, they are automatically added to the screen and any changes to their values will automatically update the results, causing their sort and pagination to be re-evaluated. var filters = [ { Type: "text", Name: "Name", Value: ko.observable(""), RecordValue: function(record) { return record.name; } }, { Type: "select", Name: "Status", Options: [ GetOption("All", "All", null), GetOption("New", "New", true), GetOption("Recently Modified", "Recently Modified", false) ], CurrentOption: ko.observable(), RecordValue: function(record) { return record.status; } } ]; Sort options are more simplistic and are also automatically added to the screen. Simply provide each option's name and value for the sort drop down as well as function to allow defining how the records are compared. This mechanism can easily be adapted for using table headers as the sort triggers. That strategy hasn't crossed my functionality needs at this point. var sortOptions = [ { Name: "Name", Value: "Name", Sort: function(left, right) { return CompareCaseInsensitive(left.name, right.name); } } ]; Paging options are completely contained by the pager model. Because we will be chaining arrays between our filtering, sorting, and pagination models, the following utility method is used to prevent errors when handing an observable array to another observable array. function GetObservableArray(array) { if (typeof(array) == 'function') { return array; }   return ko.observableArray(array); }

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  • upgraded "Compiz' and "Unity", now no Unity 3D on screen

    - by user18432
    Today when I logged in to my Ubuntu 12.04, the update manager told me of some upgrades. Compiz and Unity were in those upgrades. After I installed the upgrades, I can no longer get the Unity panel on the left side of screen or the systray at the top of screen. I now have to run Ubuntu 12.04 with Unity 2D. My laptop is a HP Pavilion dv9000 with Nvidia GeForce Go 7600 video. I tried to run "unity --reset" but it says there are serious issues with compiz. I have cut & pasted the read out from the terminal below. [09:35:02] xxxxxxx@L01U1204:~$ unity --reset unity-panel-service: no process found Checking if settings need to be migrated ...no Checking if internal files need to be migrated ...no Backend : gconf Integration : true Profile : unity Adding plugins Initializing core options...done compiz (core) - Warn: failed to receive ConfigureNotify event on 0x2e00004 compiz (core) - Warn: failed to receive ConfigureNotify event on 0x580005a compiz (core) - Warn: failed to receive ConfigureNotify event on 0x3600006 compiz (core) - Warn: failed to receive ConfigureNotify event on 0x3200255 compiz (core) - Warn: failed to receive ConfigureNotify event on 0x1600002 compiz (core) - Warn: failed to receive ConfigureNotify event on 0x1400002 Initializing composite options...done Initializing opengl options...done Initializing decor options...done Initializing vpswitch options...done Initializing snap options...done Initializing mousepoll options...done Initializing resize options...done Initializing place options...done Initializing move options...done Initializing wall options...done Initializing grid options...done I/O warning : failed to load external entity "/home/brwright/.compiz/session/10afaca1703486b216133648409481824100000130110002" Initializing session options...done Initializing gnomecompat options...done Initializing animation options...done Initializing fade options...done Initializing unitymtgrabhandles options...done Initializing workarounds options...done Initializing scale options...done compiz (expo) - Warn: failed to bind image to texture Initializing expo options...done Initializing ezoom options...done compiz (core) - Error: Couldn't load plugin '/usr/lib/compiz/libunityshell.so' : /usr/lib/compiz/libunityshell.so: undefined symbol: _ZNK5unity4dash10Controller6windowEv compiz (core) - Error: Couldn't load plugin 'unityshell' compiz (core) - Warn: unhandled ConfigureNotify on 0x7000090! compiz (core) - Warn: this should never happen. you should probably file a bug about this. compiz (core) - Warn: unhandled ConfigureNotify on 0x7000093! compiz (core) - Warn: this should never happen. you should probably file a bug about this. compiz (core) - Warn: unhandled ConfigureNotify on 0x7000096! compiz (core) - Warn: this should never happen. you should probably file a bug about this. compiz (core) - Warn: unhandled ConfigureNotify on 0x7000099! compiz (core) - Warn: this should never happen. you should probably file a bug about this. compiz (core) - Warn: unhandled ConfigureNotify on 0x700009c! compiz (core) - Warn: this should never happen. you should probably file a bug about this. compiz (core) - Warn: unhandled ConfigureNotify on 0x700009f! compiz (core) - Warn: this should never happen. you should probably file a bug about this. Initializing annotate options...done Initializing blur options...done Initializing clone options...done Initializing colorfilter options...done Initializing commands options...done Initializing cube options...done Initializing imgjpeg options...done Initializing kdecompat options...done Initializing mag options...done Initializing neg options...done Initializing obs options...done Initializing opacify options...done Initializing put options...done Initializing resizeinfo options...done Initializing ring options...done Initializing rotate options...done Initializing scaleaddon options...done Initializing screenshot options...done Initializing shift options...done Initializing staticswitcher options...done Initializing switcher options...done Initializing thumbnail options...done Initializing unityshell options...done Initializing water options...done Initializing winrules options...done Initializing wobbly options...done Setting Update "main_menu_key" Setting Update "run_key" Starting gtk-window-decorator As you can see the terminal never comes back to the CI prompt. I must do a control C to get to the CI prompt, but then the OS is frozen. I have to reboot and run Unity 2D in able to do anything on my laptop. I hope I have explained this enough and provided some useful info. I am at a loss to understand what the problem is, or what exactly what is causing the problem. Is it Unity or Compiz? Can anyone help?

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  • JMSContext, @JMSDestinationDefintion, DefaultJMSConnectionFactory with simplified JMS API: TOTD #213

    - by arungupta
    "What's New in JMS 2.0" Part 1 and Part 2 provide comprehensive introduction to new messaging features introduced in JMS 2.0. The biggest improvement in JMS 2.0 is introduction of the "new simplified API". This was explained in the Java EE 7 Launch Technical Keynote. You can watch a complete replay here. Sending and Receiving a JMS message using JMS 1.1 requires lot of boilerplate code, primarily because the API was designed 10+ years ago. Here is a code that shows how to send a message using JMS 1.1 API: @Statelesspublic class ClassicMessageSender { @Resource(lookup = "java:comp/DefaultJMSConnectionFactory") ConnectionFactory connectionFactory; @Resource(mappedName = "java:global/jms/myQueue") Queue demoQueue; public void sendMessage(String payload) { Connection connection = null; try { connection = connectionFactory.createConnection(); connection.start(); Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); MessageProducer messageProducer = session.createProducer(demoQueue); TextMessage textMessage = session.createTextMessage(payload); messageProducer.send(textMessage); } catch (JMSException ex) { ex.printStackTrace(); } finally { if (connection != null) { try { connection.close(); } catch (JMSException ex) { ex.printStackTrace(); } } } }} There are several issues with this code: A JMS ConnectionFactory needs to be created in a application server-specific way before this application can run. Application-specific destination needs to be created in an application server-specific way before this application can run. Several intermediate objects need to be created to honor the JMS 1.1 API, e.g. ConnectionFactory -> Connection -> Session -> MessageProducer -> TextMessage. Everything is a checked exception and so try/catch block must be specified. Connection need to be explicitly started and closed, and that bloats even the finally block. The new JMS 2.0 simplified API code looks like: @Statelesspublic class SimplifiedMessageSender { @Inject JMSContext context; @Resource(mappedName="java:global/jms/myQueue") Queue myQueue; public void sendMessage(String message) { context.createProducer().send(myQueue, message); }} The code is significantly improved from the previous version in the following ways: The JMSContext interface combines in a single object the functionality of both the Connection and the Session in the earlier JMS APIs.  You can obtain a JMSContext object by simply injecting it with the @Inject annotation.  No need to explicitly specify a ConnectionFactory. A default ConnectionFactory under the JNDI name of java:comp/DefaultJMSConnectionFactory is used if no explicit ConnectionFactory is specified. The destination can be easily created using newly introduced @JMSDestinationDefinition as: @JMSDestinationDefinition(name = "java:global/jms/myQueue",        interfaceName = "javax.jms.Queue") It can be specified on any Java EE component and the destination is created during deployment. JMSContext, Session, Connection, JMSProducer and JMSConsumer objects are now AutoCloseable. This means that these resources are automatically closed when they go out of scope. This also obviates the need to explicitly start the connection JMSException is now a runtime exception. Method chaining on JMSProducers allows to use builder patterns. No need to create separate Message object, you can specify the message body as an argument to the send() method instead. Want to try this code ? Download source code! Download Java EE 7 SDK and install. Start GlassFish: bin/asadmin start-domain Build the WAR (in the unzipped source code directory): mvn package Deploy the WAR: bin/asadmin deploy <source-code>/jms/target/jms-1.0-SNAPSHOT.war And access the application at http://localhost:8080/jms-1.0-SNAPSHOT/index.jsp to send and receive a message using classic and simplified API. A replay of JMS 2.0 session from Java EE 7 Launch Webinar provides complete details on what's new in this specification: Enjoy!

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  • Is this over-abstraction? (And is there a name for it?)

    - by mwhite
    I work on a large Django application that uses CouchDB as a database and couchdbkit for mapping CouchDB documents to objects in Python, similar to Django's default ORM. It has dozens of model classes and a hundred or two CouchDB views. The application allows users to register a "domain", which gives them a unique URL containing the domain name that gives them access to a project whose data has no overlap with the data of other domains. Each document that is part of a domain has its domain property set to that domain's name. As far as relationships between the documents go, all domains are effectively mutually exclusive subsets of the data, except for a few edge cases (some users can be members of more than one domain, and there are some administrative reports that include all domains, etc.). The code is full of explicit references to the domain name, and I'm wondering if it would be worth the added complexity to abstract this out. I'd also like to know if there's a name for the sort of bound property approach I'm taking here. Basically, I have something like this in mind: Before in models.py class User(Document): domain = StringProperty() class Group(Document): domain = StringProperty() name = StringProperty() user_ids = StringListProperty() # method that returns related document set def users(self): return [User.get(id) for id in self.user_ids] # method that queries a couch view optimized for a specific lookup @classmethod def by_name(cls, domain, name): # the view method is provided by couchdbkit and handles # wrapping json CouchDB results as Python objects, and # can take various parameters modifying behavior return cls.view('groups/by_name', key=[domain, name]) # method that creates a related document def get_new_user(self): user = User(domain=self.domain) user.save() self.user_ids.append(user._id) return user in views.py: from models import User, Group # there are tons of views like this, (request, domain, ...) def create_new_user_in_group(request, domain, group_name): group = Group.by_name(domain, group_name)[0] user = User(domain=domain) user.save() group.user_ids.append(user._id) group.save() in group/by_name/map.js: function (doc) { if (doc.doc_type == "Group") { emit([doc.domain, doc.name], null); } } After models.py class DomainDocument(Document): domain = StringProperty() @classmethod def domain_view(cls, *args, **kwargs): kwargs['key'] = [cls.domain.default] + kwargs['key'] return super(DomainDocument, cls).view(*args, **kwargs) @classmethod def get(cls, *args, **kwargs, validate_domain=True): ret = super(DomainDocument, cls).get(*args, **kwargs) if validate_domain and ret.domain != cls.domain.default: raise Exception() return ret def models(self): # a mapping of all models in the application. accessing one returns the equivalent of class BoundUser(User): domain = StringProperty(default=self.domain) class User(DomainDocument): pass class Group(DomainDocument): name = StringProperty() user_ids = StringListProperty() def users(self): return [self.models.User.get(id) for id in self.user_ids] @classmethod def by_name(cls, name): return cls.domain_view('groups/by_name', key=[name]) def get_new_user(self): user = self.models.User() user.save() views.py @domain_view # decorator that sets request.models to the same sort of object that is returned by DomainDocument.models and removes the domain argument from the URL router def create_new_user_in_group(request, group_name): group = request.models.Group.by_name(group_name) user = request.models.User() user.save() group.user_ids.append(user._id) group.save() (Might be better to leave the abstraction leaky here in order to avoid having to deal with a couchapp-style //! include of a wrapper for emit that prepends doc.domain to the key or some other similar solution.) function (doc) { if (doc.doc_type == "Group") { emit([doc.name], null); } } Pros and Cons So what are the pros and cons of this? Pros: DRYer prevents you from creating related documents but forgetting to set the domain. prevents you from accidentally writing a django view - couch view execution path that leads to a security breach doesn't prevent you from accessing underlying self.domain and normal Document.view() method potentially gets rid of the need for a lot of sanity checks verifying whether two documents whose domains we expect to be equal are. Cons: adds some complexity hides what's really happening requires no model modules to have classes with the same name, or you would need to add sub-attributes to self.models for modules. However, requiring project-wide unique class names for models should actually be fine because they correspond to the doc_type property couchdbkit uses to decide which class to instantiate them as, which should be unique. removes explicit dependency documentation (from group.models import Group)

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  • Zend Framework, Zend_Form_Element how to set custom name?

    - by ikso
    Hello, I have form, where some fields are looks like rows, so I can add/delete them using JS. For example: Field with ID=1 (existing row) <input id="id[1]" type="text" name="id[1]" value="1" /> <input id="name[1]" type="text" name="name[1]" value="100" /> Field with ID=2 (existing row) <input id="name[2]" type="text" name="name[2]" value="200" /> <input id="name[2]" type="text" name="name[2]" value="200" /> new row created by default (to allow add one more row to existing rows) <input id="id[n0]" type="text" name="id[n0]" value="" /> <input id="name[n0]" type="text" name="name[n0]" value="" /> new row created by JS <input id="id[n1]" type="text" name="id[n1]" value="" /> <input id="name[n1]" type="text" name="name[n1]" value="" /> So than we will proceed form, we will know what rows to update and what to add (if index starts with "n" - new, if index is number - existent element). I tried subforms... but do I have to create subform for each field? If I use following code: $subForm = new Zend_Form_SubForm(); $subForm->addElement('Text', 'n0'); $this->addSubForm($subForm, 'pid'); $subForm = new Zend_Form_SubForm(); $subForm->addElement('Text', 'n0'); $this->addSubForm($subForm, 'name'); What is the best way for this? 1) Use subforms? 2) Extend Zend/Form/Decorator/ViewHelper.php to use names like name[nX]? 3) Other solutions? Thanks.

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  • How to declare dependent style names with UiBinder

    - by Eduard Wirch
    I have a simple UiBinder widget containing a TextArea: <!DOCTYPE ui:UiBinder SYSTEM "http://dl.google.com/gwt/DTD/xhtml.ent"> <ui:UiBinder xmlns:ui="urn:ui:com.google.gwt.uibinder" xmlns:g="urn:import:com.google.gwt.user.client.ui"> <g:TextArea visibleLines="3" /> </ui:UiBinder> I want to control the background color of this textarea for writeable and read only states. GWT uses the "-readonly" style name decorator to achieve this. So I try this: <!DOCTYPE ui:UiBinder SYSTEM "http://dl.google.com/gwt/DTD/xhtml.ent"> <ui:UiBinder xmlns:ui="urn:ui:com.google.gwt.uibinder" xmlns:g="urn:import:com.google.gwt.user.client.ui"> <ui:style> .textBoxStyle { background-color:yellow; } .textBoxStyle-readonly { background-color:lightgray; } </ui:style> <g:TextArea styleName="{style.textBoxStyle}" visibleLines="3" /> </ui:UiBinder> Obviously this won't work because style names are obfuscated for CssResources resulting in something like this: .G1x26wpeN { background-color:yellow } .G1x26wpeO { background-color: lightgray; } The result HTML for writeable textarea looks like this: <textarea tabindex="0" class="G1x26wpeN" rows="3"/> The read only textarea looks like this: <textarea tabindex="0" class="G1x26wpeN G1x26wpeN-readonly" readonly="" rows="3"/> How do I declare the style so GWT will obfuscate the primary part but not the "-readonly" decdorator? I know that I can disable the obfuscation for the entire style name. But I'd like to keep the obfuscation while making use of the decorators.

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  • Preloading multiple comboboxes/listbox itemssource with enumerated values using WCF RIA Services

    - by Dale Halliwell
    I would like to be able to load several RIA entitysets in a single call without chaining/nesting several small LoadOperations together so that they load sequentially. I have several pages that have a number of comboboxes on them. These comboboxes are populated with static values from a database (for example status values). Right now I preload these values in my VM by one method that strings together a series of LoadOperations for each type that I want to load. For example: public void LoadEnums() { context.Load(context.GetMyStatusValues1Query()).Completed += (s, e) => { this.StatusValues1 = context.StatusValues1; context.Load(context.GetMyStatusValues2()).Completed += (s1, e1) => { this.StatusValues2 = context.StatusValues2; context.Load(context.GetMyStatusValues3Query()).Completed += (s2, e2) => { this.StatusValues3 = context.StatusValues3; (....and so on) }; }; }; }; While this works fine, it seems a bit nasty. Also, I would like to know when the last loadoperation completes so that I can load whatever entity I want to work on after this, so that these enumerated values resolve properly in form elements like comboboxes and listboxes. (I think) I can't do this easily above without creating a delegate and calling that on the completion of the last loadoperation. So my question is: does anyone out there know a better pattern to use, ideally where I can load all my static entitysets in a single LoadOperation?

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  • Creating a drop-down row in displaytag

    - by bphilipnyc
    I am currently using displaytag for tabular data, but would like to create a "kayak.com-like" interface where when a user clicks a row, the user is shown more details about the particular row without a page refresh. I tried using a decorator to return javascript that would do this. The javascript is executed, but it is only reflected in the column where it was rendered. I am looking to create a new row with the data. e.g.: public class CustomDecorator extends TableDecorator { public String getDetailsRow() { MyObject object = (MyObject)this.getCurrentRowObject(); return "<a onClick=\"myjsfunction(object.getId()); return true\">Details</a>"; } } ...and in the JSP I would have a detailsRow property nested between the display:table tags: <display:column property="detailsRow" sortable="false" /> Any tips on how to create a new row? The solution may be in the way that the javascript is written - I'm not an expert with Javascript, so any tips would be appreciated. Is there a better way to do this with displaytag? I don't know of any explicit integration that displaytag has with javascript (like an "onclick" parameter) either. This is my first question on stackoverflow, btw - so please let me know whether you need more detail.

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  • How Do I Use jQuery/JavaScript To Open A Popup Window/Tab (ASPX Login Page) & Then Pass Values To Op

    - by Terry Robinson
    Hi All, We currently have two asp.net 2.x web applications and we need to perform the following functionality: From one application, we want to auto-login to the other web application automatically in a new tab; using the same browser instance/window. So the process is: Open New Window/Tab With Second System URL/Login Page Wait For Popup Window/Tab Page To Load (DOM Ready?) OnPopupDomReady { Get Usename, Password, PIN Controls (jQuery Selectors) and Populate In Code Then Click Login Button (All Programatically). } I am currently using JavaScript to Open the window as follows: <script type="text/javascript"> $(document).ready(function () { $('a[rel="external"]').click(function () { window.open($(this).attr('href')); return false; }); }); </script> I would like to use jQuery chaining functionality if possible to extent the method above so that I can attach a DOM Ready event to the popped up page and then use that event to call a method on the code behind of the popped up page to automatically login. Something similar to this (Note: The Following Code Sample Does Not Work, It Is Here To Try And Help Illustrate What We Are Trying To Achieve)... <script type="text/javascript"> $(document).ready(function () { $('a[rel="external"]').click(function () { window.open($(this).attr('href').ready(function () { // Use JavaScript (Pref. jQuery Partial Control Name Selectors) To Populate Username/Password TextBoxes & Click Login Button. }) }); }); </script> Our Architecture Is As Follows: We have the source for both products (ASP.NET WebSite[s]) and they are run under different app. pools in IIS. I hope this all makes sense, and if my plan is not going to work, please provide hints ;) Thanks All/Kind Regards, Terry Robinson.

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  • Looping Redirect with PyFacebook and Google App Engine

    - by Nick Gotch
    I have a Python Facebook project hosted on Google App Engine and use the following code to handle initialization of the Facebook API using PyFacebook. # Facebook Initialization def initialize_facebook(f): # Redirection handler def redirect(self, url): logger.info('Redirecting the user to: ' + url) self.response.headers.add_header("Cache-Control", "max-age=0") self.response.headers.add_header("Pragma", "no-cache") self.response.out.write('<html><head><script>parent.location.replace(\'' + url + '\');</script></head></html>') return 'Moved temporarily' auth_token = request.params.get('auth_token', None) fbapi = Facebook(settings['FACEBOOK_API_KEY'], settings['FACEBOOK_SECRET_KEY'], auth_token=auth_token) if not fbapi: logger.error('Facebook failed to initialize') if fbapi.check_session(request) or auth_token: pass else: logger.info('User not logged into Facebook') return lambda a: redirect(a, fbapi.get_login_url()) if fbapi.added: pass else: logger.info('User does not have ' + settings['FACEBOOK_APP_NAME'] + ' added') return lambda a: redirect(a, fbapi.get_add_url()) # Return the validated API logger.info('Facebook successfully initialized') return lambda a: f(a, fbapi=fbapi) I'm trying to set it up so that I can drop this decorator on any page handler method and verify that the user has everything set up correctly. The issue is that when the redirect handler gets called, it starts an infinite loop of redirection. I tried using an HTTP 302 redirection in place of the JavaScript but that kept failing too. Does anyone know what I can do to fix this? I saw this similar question but there are no answers.

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  • Login URL using authentication information in Django

    - by fuSi0N
    I'm working on a platform for online labs registration for my university. Login View [project views.py] from django.http import HttpResponse, HttpResponseRedirect, Http404 from django.shortcuts import render_to_response from django.template import RequestContext from django.contrib import auth def index(request): return render_to_response('index.html', {}, context_instance = RequestContext(request)) def login(request): if request.method == "POST": post = request.POST.copy() if post.has_key('username') and post.has_key('password'): usr = post['username'] pwd = post['password'] user = auth.authenticate(username=usr, password=pwd) if user is not None and user.is_active: auth.login(request, user) if user.get_profile().is_teacher: return HttpResponseRedirect('/teachers/'+user.username+'/') else: return HttpResponseRedirect('/students/'+user.username+'/') else: return render_to_response('index.html', {'msg': 'You don\'t belong here.'}, context_instance = RequestContext(request) return render_to_response('login.html', {}, context_instance = RequestContext(request)) def logout(request): auth.logout(request) return render_to_response('index.html', {}, context_instance = RequestContext(request)) URLS #========== PROJECT URLS ==========# urlpatterns = patterns('', (r'^media/(?P<path>.*)$', 'django.views.static.serve', {'document_root': settings.MEDIA_ROOT }), (r'^admin/', include(admin.site.urls)), (r'^teachers/', include('diogenis.teachers.urls')), (r'^students/', include('diogenis.students.urls')), (r'^login/', login), (r'^logout/', logout), (r'^$', index), ) #========== TEACHERS APP URLS ==========# urlpatterns = patterns('', (r'^(?P<username>\w{0,50})/', labs), ) The login view basically checks whether the logged in user is_teacher [UserProfile attribute via get_profile()] and redirects the user to his profile. Labs View [teachers app views.py] from django.http import HttpResponse, HttpResponseRedirect, Http404 from django.shortcuts import render_to_response from django.template import RequestContext from django.contrib.auth.decorators import user_passes_test from django.contrib.auth.models import User from accounts.models import * from labs.models import * def user_is_teacher(user): return user.is_authenticated() and user.get_profile().is_teacher @user_passes_test(user_is_teacher, login_url="/login/") def labs(request, username): q1 = User.objects.get(username=username) q2 = u'%s %s' % (q1.last_name, q1.first_name) q2 = Teacher.objects.get(name=q2) results = TeacherToLab.objects.filter(teacher=q2) return render_to_response('teachers/labs.html', {'results': results}, context_instance = RequestContext(request)) I'm using @user_passes_test decorator for checking whether the authenticated user has the permission to use this view [labs view]. The problem I'm having with the current logic is that once Django authenticates a teacher user he has access to all teachers profiles basically by typing the teachers username in the url. Once a teacher finds a co-worker's username he has direct access to his data. Any suggestions would be much appreciated.

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  • rails search nested set (categories and sub categories)

    - by bob
    Hello, I am using the http://github.com/collectiveidea/awesome_nested_set awesome nested set plugin and currently, if I choose a sub category as my category_id for an item, I can not search by its parent. Category.parent Category.Child I choose Category.child as the category that my item is in. So now my item has category_id of 4 stored in it. If I go to a page in my rails application, lets say teh Category page and I am on the Category.parent's page, I want to show products that have category_id's of all the descendants as well. So ideally i want to have a find method that can take into account the descendants. You can get the descendants of a root by calling root.descendants (a built in plugin method). How would I go about making it so I can query a find that gets the descendants of a root instead of what its doing now which is binging up nothing unless the product had a specific category_id of the Category.parent. I hope I am being clear here. I either need to figure out a way to create a find method or named_scope that can query and return an array of objects that have id's corresponding tot he descendants of a root OR if I have any other options, what are they? I thought about creating a field in my products table like parent_id which can keep track of the parent so i can then create two named scopes one finding the parent stuff and one finding the child stuff and chaining them. I know I can create a named scope for each child and chain them together for multiple children but this seems a very tedious process and also, if you add more children, you would need to specify more named scopes.

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  • using python 'with' statement with iterators?

    - by Stephen
    Hi, I'm using Python 2.5. I'm trying to use this 'with' statement. from __future__ import with_statement a = [] with open('exampletxt.txt','r') as f: while True: a.append(f.next().strip().split()) print a The contents of 'exampletxt.txt' are simple: a b In this case, I get the error: Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/tmp/python-7036sVf.py", line 5, in <module> a.append(f.next().strip().split()) StopIteration And if I replace f.next() with f.read(), it seems to be caught in an infinite loop. I wonder if I have to write a decorator class that accepts the iterator object as an argument, and define an __exit__ method for it? I know it's more pythonic to use a for-loop for iterators, but I wanted to implement a while loop within a generator that's called by a for-loop... something like def g(f): while True: x = f.next() if test1(x): a = x elif test2(x): b = f.next() yield [a,x,b] a = [] with open(filename) as f: for x in g(f): a.append(x)

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  • Zend: How to populate data to checkboxes?

    - by NAVEED
    I am working on zend. I have a form with some checkboxes. I want to get data from database and populate this data to this form. If '1' is stored in table field then tick the check box otherwise leave it alone. In textboxes and dropdowns, data is easily populated but how to check a checkbox in action. I am creating checkboxes and textboxes elements like this in form.php: // Person name $person = $this->CreateElement('text', 'name'); $person->setLabel('Name'); $elements[] = $person; // Organization name $person = $this->CreateElement('text', 'organization'); $person->setLabel('Organization'); $elements[] = $person; // isAdmin Checkbox $isAdmin = $this->CreateElement('checkbox', 'isAdmin'); $isAdmin->setLabel('Admin'); $elements[] = $isAdmin; $this->addElements($elements); $this->setElementDecorators(array('ViewHelper')); // set form decorator (what script will render the form) $this->setDecorators(array(array('ViewScript' , array('viewScript' => 'organization/accessroles-form.phtml')))); And populating data like this (for example): // Prepare data to populate $data['name'] = 'Naveed'; $data['organization'] = 'ABC'; $data['isAdmin'] = '1'; // Populate editable data $this->view->form->populate( $data ); It is populating data in textboxes but not checking the checkbox? Any idea that how to check a checkbox from action? Thanks

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