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  • Rails Model multiple column uniqueness

    - by Jty.tan
    I am making a Viewer model with belongs_to :users belongs_to :orders that joins the models Users and Orders with a :has_many :through => :viewers. And the Viewer model has the attributes of user_id and order_id. How would I set it up so that new viewers are only accepted if both user_id and order_id are unique in the same row? I remember in MySQL being able to do so with a flag (although I can't for the life of me remember what it was), but I'm not sure how to do it with Rails. Can I do something like (for Viewer.rb) validates_uniqueness_of :user_id, :scope => :order_id?

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  • Hibernate: same generated value in two properties

    - by Markos Fragkakis
    Hi, I have an entity A with fields: aId (the system id) bId I want the first to be generated: @Id @Column(name = "PRODUCT_ID", unique = true, nullable = false, precision = 12, scale = 0) @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "PROD_GEN") @BusinessKey public Long getAId() { return this.aId; } I want the bId to be initially exactly as the aId. One approach is to insert the entity, then get the aId generated by the DB (2nd query) and then update the entity, setting the bId to be equal to aId (3rd query). Is there a way to get the bId to get the same generated value as aId? Note that afterwards, I want to be able to update bId from my gui. If the solution is JPA, even better.

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  • Why won't this SQL CAST work?

    - by Kev
    I have a nvarchar(50) column in a SQL Server 2000 table defined as follows: TaskID nvarchar(50) NULL I need to fill this column with some random SQL Unique Identifiers (I am unable to change the column type to uniqueidentifier). I tried this: UPDATE TaskData SET TaskID = CAST(NEWID() AS nvarchar) but I got the following error: Msg 8115, Level 16, State 2, Line 1 Arithmetic overflow error converting expression to data type nvarchar. I also tried: UPDATE TaskData SET TaskID = CAST(NEWID() AS nvarchar(50)) but then got this error: Msg 8152, Level 16, State 6, Line 1 String or binary data would be truncated. I don't understand why this doesn't work but this does: DECLARE @TaskID nvarchar(50) SET @TaskID = CAST(NEW() AS nvarchar(50)) I also tried CONVERT(nvarchar, NEWID()) and CONVERT(nvarchar(50), NEWID()) but got the same errors.

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  • Quickly retrieve the subset of properties used in a huge collection in C#

    - by ccornet
    I have a huge Collection (which I can cast as an enumerable using OfType<()) of objects. Each of these objects has a Category property, which is drawn from a list somewhere else in the application. This Collection can reach sizes of hundreds of items, but it is possible that only, say, 6/30 of the possible Categories are actually used. What is the fastest method to find these 6 Categories? The size of the huge Collection discourages me from just iterating across the entire thing and returning all unique values, so is there a faster method of accomplishing this? Ideally I'd collect the categories into a List.

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  • Encoding a string as an integer .NET

    - by Paul Knopf
    I have a string that I would like represented uniquely as an integer. For example: A3FJEI = 34950140 How would I go about writing a EncodeAsInteger(string) method. I understand that the amount of characters in the string will make the integer increase greatly, forcing the value to become a long, not an int. Since I need the value to be an integer, I don't need the numerical representation to be entirely unique to the string. Maybe I can foreach through all the characters of the string and sum the numerical keycode of the character.

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  • INSERT INTO ... SELECT FROM ... ON DUPLICATE KEY UPDATE

    - by dnagirl
    I'm doing an insert query where most of many columns would need to be updated to the new values if a unique key already existed. It goes something like this: INSERT INTO lee(exp_id, created_by, location, animal, starttime, endtime, entct, inact, inadur, inadist, smlct, smldur, smldist, larct, lardur, lardist, emptyct, emptydur) SELECT id, uid, t.location, t.animal, t.starttime, t.endtime, t.entct, t.inact, t.inadur, t.inadist, t.smlct, t.smldur, t.smldist, t.larct, t.lardur, t.lardist, t.emptyct, t.emptydur FROM tmp t WHERE uid=x ON DUPLICATE KEY UPDATE ...; //update all fields to values from SELECT, except for exp_id, created_by, location, animal, starttime, endtime I'm not sure what the syntax for the UPDATE clause should be. How do I refer to the current row from the SELECT clause?

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  • django m2m how can i get m2m table elements in a view

    - by dana
    i have a model using m2m feature: class Classroom(models.Model): user = models.ForeignKey(User, related_name = 'classroom_creator') classname = models.CharField(max_length=140, unique = True) date = models.DateTimeField(auto_now=True) open_class = models.BooleanField(default=True) members = models.ManyToManyField(User,related_name="list of invited members", through = 'Membership') and i want to take all members of one class in a view and display them using the template system. In the view, i'm trying to take all the members from a classroom like that: def inside_classroom(request,classname): try: theclass = Classroom.objects.get(classname = classname) members = Members.objects.all() etc but it doesn't work,(though the db_table is named Classroom_Members) i guess i have to use another query for getting all the members from the classroom classname. also, i want to verify if the request.user is a member using (if request.user in members) how can i het those members? Thanks in advance!

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  • Are concurrency issues possible when using the WCF Service Behavoir attribute set to ConcurrencyMode

    - by Brandon Linton
    We have a WCF service that makes a good deal of transactional NHibernate calls. Occasionally we were seeing SQL timeouts, even though the calls were updating different rows and the tables were set to row level locking. After digging into the logs, it looks like different threads were entering the same point in the code (our transaction using block), and an update was hanging on commit. It didn't make sense, though, because we believed that the following service class attribute was forcing a unique execution thread per service call: [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.PerCall)] We recently changed the concurrency mode to ConcurrencyMode.Single and haven't yet run into any issues, but the bug was very difficult to reproduce (if anyone has any thoughts on flushing a bug like that out, let me know!). Anyway, that all brings me to my question: shouldn't an InstanceContextMode of PerCall enforce thread-safety within the service, even if the ConcurrencyMode is set to multiple? How would it be possible for two calls to be serviced by the same service instance? Thanks!

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  • Creating an Extremely Large Index in Oracle

    - by Rudiger
    Can someone look at the linked reference and explain to me the precise statements to run? Oracle DBA's Guide: Creating a Large Index Here's what I came up with... CREATE TEMPORARY TABLESPACE ts_tmp TEMPFILE 'E:\temp01.dbf' SIZE 10000M REUSE AUTOEXTEND ON EXTENT MANAGEMENT LOCAL; ALTER USER me TEMPORARY TABLESPACE ts_tmp; CREATE UNIQUE INDEX big_table_idx ON big_table ( record_id ); DROP TABLESPACE ts_tmp; Edit 1 After this index was created, I ran an explain plan for a simple query and get this error: ORA-00959: tablespace 'TS_TMP' does not exist It seems like it's not temporary at all... :(

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  • How to generate a good random seed to pass to srand()?

    - by zr
    Hi, I am writing a C++ program which needs to create a temporary file for its internal usage. I would like to allow concurrent executions of the program by running multiple proccesses, so the temporary file name needs to be randomized, that way each spawned process will generate a unique temporary file name for its own use. I am using rand() to generate random characters for part of the file name, so i need to initialize the random number generator's seed using srand(). What options are there for passing a good argument to srand() such that two processes will not be initialized with the same seed value? My code needs to work both on Windows and pn Linux TIA.

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  • Maximizing the number of threads to fully utilize all available resources without hindering overall

    - by Matt
    Let's say I have to generate a bunch of result files, and I want to make it as fast as possible. Each result file is generated independently of any other result file; in fact, one could say that each result file is agnostic to every other result file. The resources used to generate each result file is also unique to each. How can I dynamically decide the optimal number of threads to run simultaneously in order to minimize the overall run time? Is my only option to write my own thread manager that watches performance counters and adjust accordingly or does there exists some solid classes that already accomplish this?

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  • Selecting an element based on class and id in jquery - similar to an SQL query

    - by Ankur
    I want to select an element based on it's class and id, I have seen many similar questions on SO. Most of the users ask why would you ever want to do this - which is not very helpful, trust me, this is the simplest way of solving my UI problem, and it's a very unique and intereting UI related to making generic triple stores easily browsable. At the moment the jQUery looks like this: $(document).ready( function() { $(".predicates").hide(); $(".objects").hide(); $("#subject").click( function() { $("#predId, .predicates").toggle(); // this line } ); $("#predId").click( function() { $("#objId, .objects").toggle(); } ); }); The line I am really interested in is this $("#predId, .predicates").toggle(); how do I get the select to ensure that both #predId and .predicates are true, at the moment it seems that only one or the other has to be true. Is there something like an && operator?

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  • Google App Engine Project hierarchy

    - by Ron
    Hey guys, I'm working on a google app engine (with Django) and I just can't figure out what's a good practice for folder hierarchy.. I've looked at this: Project structure for Google App Engine but one thing isn't clear - what if I have static folder (like js files) that are unique to my app, not project? where do they go? my current hierarchy is: proj static ** js ** css myapp ** templates So when a template inside my app sends a GET for js/script.js. this gets redirected to /myapp/js/script.js, which my server doesn't recognize. here is my project url.py: urlpatterns = patterns('', (r'^myapp/', include('myapp.urls')), ) and here is my myapp.urls.py: urlpatterns = patterns('myapp.views', (r'^$', 'myapp.views.index'), ) how should I rearrange this to work? thanks!

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  • How do I do multipled level routes best in MVC

    - by Lilja
    I have a site where I would like an URL like: /Some maincategory name/{id}/Some subcategory name/{id}/Some item name/{id} I include the IDs of each level since the name is not unique. This is doable but I have to create a new routing for each level. My Html.ActionLink also looks nasty. Each level has it's own controller since the levels are completely different. The URLs could be something like this: _/Birds/2/Waders/4/Flamingos/23_ _/Mammals/5/Dogs/23/Longeared/25/Somedog/76_ _/Insects/7/Spiders_ This is just an example and not what I'm going to use. My applications has nothing to do with animals. Is there a good way of doing this or should I use the standard routing instead?

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  • Overriding PEAR error handler

    - by Rolf
    Hi everyone, I'm currently working on an application that requires lots of external libraries. My job right now is set a unique error handler that will manage every error. So far, I found 7 different types of PEAR errors: PEAR_ERROR_RETURN: PEAR_ERROR_EXCEPTION: PEAR_ERROR_CALLBACK: PEAR_ERROR_EXCEPTION: PEAR_ERROR_PRINT: PEAR_ERROR_TRIGGER: PEAR_ERROR_DIE: I want to handle only the serious error (like the native E*_ERROR). The only problem is I have absolutely no idea about PEAR error criticity ! Those names are more related to the way of handling them than to their seriousness... Is there a real documentation about it ? I guess a better solution would consist in using their pushErrorHandling, but I just don't understand how to use it... If someone here knows, I'd be grateful... Thanks in advance !

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  • How to perform COUNT() or COUNT(*)

    - by ninumedia
    I have a list of tags in a database. Ex: villan hero spiderman superman superman I wanted to obtain a sorted list of the tag names in ascending order and the number of times the unique tag appeared in the database. I wrote this code: Ex: SELECT hashtag.tag_name, COUNT( * ) AS number FROM hashtag GROUP BY hashtag.tag_name ORDER BY hashtag.tag_name ASC This yields the correct result: hero - 1 spiderman - 1 superman - 2 villan - 1 How can I obtain the full COUNT of this entire list. The answer should be 4 in this case because there are naturally 4 rows. I can't seem to get a correct COUNT() without the statement failing. Thanks so much for the help! :)

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  • Display field from another table in SQL

    - by Roland Bengtsson
    I'm a newbie with SQL... Now I want to do display some instances of AddrDistances from DevExpress CxGrid with SQL. Select Cast((DistanceAsMeters * 0.001) as Decimal(8,1)) DistanceAsKm, bold_id, created, fromAddress, toAddress From AddrDistance Where DistanceAsMeters = 0 and PseudoDistanceAsCostKm = 0 and not AddrDistance.bold_id in (select bold_id from DistanceQueryTask) Order By Created Desc This SQL is working and the result is: DistanceAsKM Bold_ID Created FromAddress ToAddress 0 134808 16.02.2010 121795 134570 0 121701 10.03.2010 120850 122991 The result I want is this: DistanceAsKM Bold_ID Created FromAddress ToAddress 0 134808 16.02.2010 Kalmar Stockholm 0 121701 10.03.2010 Falkenberg Oslo So the amount of rows is right but I want to replace the numbers in FromAddress and ToAddress with strings from another table. The numbers shows here is just the boldid. Every object in the database have an unique boldid. The addresses above is stored in table Address and it have a City field with the column and a boldid as a key. What should I write in SQL to get this right ? Is there something in the CxGrid that could help here ? Regards

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  • gethostbyname in C

    - by Matic
    I don't know how to write applications in C, but I need a tiny program that does: lh = gethostbyname("localhost"); output = lh->h_name; output variable is to be printed. The above code is used in PHP MongoDB database driver to get the hostname of the computer (hostname is part of an input to generate an unique ID). I'm skeptical that this will return the hostname, so I'd like some proof. Any code examples would be most helpful. Happy day, Matic

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  • Selecting contents of Label Control

    - by j-t-s
    Hi All I have what I consider to be a pretty unique problem here, and no idea how to implement. From what I've seen, there is no documentation, tutorials, samples and/or articles on this. I've spent weeks researching, with nothing to show. The problem: I need the user to be able to select the contents of a Label Control at runtime, and edit it. If this can be done by extending the existing Label control, great! Or, if this requires a whole new Label Control to be created, fine. So be it. Using a TextBox is not an option I'm afraid. Any help at all is greatly appreciated! Thank you, jase

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  • database vs flat file, which is a faster structure for "regex" matching with many simultaneous reque

    - by Jamex
    Hi, which structure returns faster result and/or less taxing on the host server, flat file or database (mysql)? Assume many users (100 users) are simultaneously query the file/db. Searches involve pattern matching against a static file/db. File has 50,000 unique lines (same data type). There could be many matches. There is no writing to the file/db, just read. Is it possible to have a duplicate the file/db and write a logic switch to use the backup file/db if the main file is in use? Which language is best for the type of structure? Perl for flat and PHP for db? Addition info: If I want to find all the cities have the pattern "cis" in their names. Which is better/faster, using regex or string functions? Please recommend a strategy TIA

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  • database vs flat file, which is a faster structure for regex matching with many simultaneous request

    - by Jamex
    Hi, which structure returns faster result and/or less taxing on the host server, flat file or database (mysql)? Assume many users (100 users) are simultaneously query the file/db. Searches involve pattern matching using regex against a static file/db. File has 50,000 unique lines (same data type). There could be many matches. There is no writing to the file/db, just read. Is it possible to have a duplicate the file/db and write a logic switch to use the backup file/db if the main file is in use? Which language is best for the type of structure? Perl for flat and PHP for db? TIA

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  • How do people manage changes to common library files stored across mutiple (Mercurial) repositories?

    - by mckoss
    This is perhaps not a question unique to Mercurial, but that's the SCM that I've been using most lately. I work on multiple projects and tend to copy source code for libraries or utilities from a previous project to get a leg up on starting a new project. The problem comes in when I want to merge all the changes I made in my latest project, back into a "master" copy of those shared library files. Since the files stored in disjoint repositories will have distinct version histories, Mercurial won't be able to perform an intelligent merge if I just copy the files back to the master repo (or even between two independent projects). I'm looking for an easy way to preserve the change history so I can merge library files back to the master with a minimum of external record keeping (which is one of the reasons I'm using SVN less as merges require remembering when copies were made across branches). Perhaps I need to do a bit more up-front organization of my repository to prepare for a future merge back to a common master.

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  • Concatenating databases with Squeryl

    - by Pengin
    I'm trying to use Squeryl to take the contents of a table from one database, and append it to the equivalent table in another database. The primary key will have to be reassigned in the process, but I'm getting the error NULL not allowed for column "SIMID". Why is this? object Concatenator { def main(args: Array[String]) { Class.forName("org.h2.Driver"); val seshA = Session.create( java.sql.DriverManager.getConnection("jdbc:h2:file:data/resultsA", "sa", "password"), new H2Adapter ) val seshB = Session.create( java.sql.DriverManager.getConnection("jdbc:h2:file:data/resultsB", "sa", "password"), new H2Adapter ) using(seshA){ import Library._ from(sims){s => select(s)}.foreach{item => using(seshB){ sims.insert(item); } } } } case class Simulation( @Column("SIMID") var id: Long, val date: Date ) extends KeyedEntity[Long] object Library extends Schema { val sims = table[Simulation] on(sims)(s => declare( s.id is(unique, indexed, autoIncremented) )) } }

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  • What keying option does the keychain use?

    - by Rudiger
    I have read into the keychain and have found that it uses Triple DES. What I can't find is what keying option it uses. I am guessing / hoping that its keying option 1 where all 3 passwords are unique but if thats the case I can only think of two passwords it can use (user password and App ID that comes from your dev cert) so where is the third coming from? Is it a key private to Apple? If its keying option 2 (first and third key are the same) it might not be secure enough for our company to rely on. Although that might sound paranoid I have to justify to our security department that it is secure enough.

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  • phonegap crossplatform redirection to local file

    - by Marco Gagliardi
    Hi I'm developing a phonegap + JQueryMobile app, which should be correctly executed on Android, iOs and WindowsPhone as well. I need to exploit an external service wich requires one callback url to redirect the app to in case of success, and one in case of error (pretty common situation. In my case both will be local files, say www/success.html and www/error.html). Of course I could write different paths for each device (e.g. file:///android_asset/www/success.html on Android), but i'm wondering if the framework provide a more simple elegant solution. So the questions is, how can i get a unique absolute URL wich allows me to perform a cross-platform HTTP redirection from a remote web page to a local file within a phonegap application? Thanks

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