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  • Designing Business Objects to indicate constraints such as Max Length

    - by JR
    Is there a standard convention when designing business objects for providing consumers with a way to discover constraints such as a property's maximum length? It could be used up in the UI layer to, for example, set a Textbox's MaxLength property according to the maximum length limit back in the business object. Is there a standard design approach for this?

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  • Unique number generation with Java Server Faces

    - by Buddhika Ariyaratne
    I am developing an application for a medical channelling centre where multiple users reserve bookings for doctors with JSF and JPA. A sequence number is unique to the Doctor, Date and Session. I tried to get a unique sequence number from counting the previous bookings and add one, but if two requests comes at the same time, two bookings get the same number causing trouble to functionality. How can I get unique number in this case? Can I use an application wide bean to generate it? (I thought it is not practicle to get the unique number from the database sequence number as there are several doctors, sessions and daily they have to have different booking number.)

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  • Compare Error logs across service fleet, find unique errors

    - by neuroelectronic
    I'm looking for a tool where I can list the servers to check, the location of the file and it would return a list of the most common errors across those servers (say like 2 or 3 servers for report brevity) and get a report something like this Server.A Server.B Server.C -------- -------- -------- 42 error.X 39 error.X 61 error.X 21 error.Y 7 error.Y 5 error.A 17 error.B 6 error.A 4 error.Y 4 error.A 2 error.R 3 error.S 3 error.R 1 error.S 1 error.R Of course, excluding timestamps and other error details and just grepping out the common sub-strings and listing them like so. I'd be able to look at the table and see that error.B is unique to Server.A and conclude that there is something up with Server.A. Does something like this already exist? Is this something I'll have to code myself? I'm not necessarily looking for this specific report, just the functionality to find unique errors across a set of error logs.

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  • F# Static Member Type Constraints

    - by Stephen Swensen
    I'm trying to define a function, factorize, which uses structural type constraints (requires static members Zero, One, +, and /) similar to Seq.sum so that it can be used with int, long, bigint, etc. I can't seem to get the syntax right, and can't find a lot of resources on the subject. This is what I have, please help. let inline factorize (n:^NUM) = ^NUM : (static member get_Zero: unit->(^NUM)) ^NUM : (static member get_One: unit->(^NUM)) let rec factorize (n:^NUM) (j:^NUM) (flist: ^NUM list) = if n = ^NUM.One then flist elif n % j = ^NUM.Zero then factorize (n/j) (^NUM.One + ^NUM.One) (j::flist) else factorize n (j + ^NUM.One) (flist) factorize n (^NUM.One + ^NUM.One) []

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  • Establish draggable content constraints depending on position

    - by drukelly
    Asking all jQuery experts! How would I go about setting up constraints for a draggable element depending on its positioning? I have a basic example here. I thought it would be as simple as adding an option, containment. Ideally, I want it to drag within the following box: top: 0px left: 0px top: -263px left: -272px top: 0px left: -272px top: -263px left: 0px Is there a way to drag the element within the parameters above so you don't the extra white space? I appreciate the help!

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  • SQL Server 2005 drop column with constraints

    - by Julien N
    Hi ! In Sql Server 2005 I have a column with a "DEFAULT" constraint. I'd like to create a script that drops that column. The problem is that is returns me that error : Msg 5074, Level 16, State 1, Line 1 The object 'DF__PeriodSce__IsClo__4BCC3ABA' is dependent on column 'IsClosed'. Msg 4922, Level 16, State 9, Line 1 ALTER TABLE DROP COLUMN IsClosed failed because one or more objects access this column. I couldn't find an easy way to drop a column and all its associated constraints (only found big scripts that look into system table... there MUST (!!) be a "nice" way to do that !). And as the DEFAULT constraint's name has been randomly generated, I can't drop it by name. Thanks for your help.

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  • Constraints when using WCF for an online multiplayer game

    - by Etan
    I want to build a service oriented game server and client using WCF where users can play card games on different tables after they logged in with an account. I would like to choose WCF due to it's flexibility in exchanging the communication channels. Maybe, a web interface will be added later which can then just use an other channel class. An additional plus is the ability for contexts which could be used to track a user over a whole gaming session. Are there some constraints I should be aware of when using WCF for the communication between the client and the server?

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  • Confusion about Nullable<T> constraints

    - by n535
    Greetings everybody. I am sorry, if this was already asked before (searched in vain) or is really very simple, but i just can't get it. The MSDN definition of a Nullable type, states, that it is defined in a following manner: [SerializableAttribute] public struct Nullable<T> where T : struct, new() So the question is quite straightforward: How is this definition possible? Or this is just a typo? Every value type already has a default constructor. Indeed, when i try to compile something like this, the compiler reasonably says, that it is illegal to apply both constraints at the same time, because the second one is implicitly included in a first one. Thanks in advance.

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  • Java library to partially export a database while respecting referential integrity constraints

    - by Mwanji Ezana
    My production database is several GB's uncompressed and it's getting to be a pain to download and run locally when trying to reproduce a bug or test a feature with real data. I would like to be able to select the specific records that interest me, then have the library figure out what other records are necessary to produce a dataset that respects the databases integrity constraints and finally print it out as a list of insert statements or dump that I can restore. For example: given Author, Blog and Comment tables when I select comments posted after a certain date I should get inserts for the Blog records the comments have foreign keys to and the Author records those Blogs have foreign keys to.

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  • Haskell: Defaulting constraints to type

    - by yairchu
    Consider this example: applyKTimes :: Integral i => i -> (a -> a) -> a -> a applyKTimes 0 _ x = x applyKTimes k f x = applyKTimes (k-1) f (f x) applyThrice :: (a -> a) -> a -> a applyThrice = applyKTimes 3 The 3 in applyThrice is defaulted by GHC to an Integer as shown when compiling with -Wall: Warning: Defaulting the following constraint(s) to type 'Integer' 'Integral t' arising from a use of 'applyKTimes' So I guess that Integer is the default Integral a => a. Is there a way to define "default types" for other constraints too? Is using default types bad practice? (it does complain when using -Wall..)

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  • How to solve 'Badly constructed integrity constraints' in doctrine

    - by Carson
    When I execute the command './doctrine build-all-reload' It comes out the following output: build-all-reload - Are you sure you wish to drop your databases? (y/n) y build-all-reload - Successfully dropped database for connection named 'doctrine' build-all-reload - Generated models successfully from YAML schema build-all-reload - Successfully created database for connection named 'doctrine' Badly constructed integrity constraints. Cannot define constraint of different f ields in the same table. Here is the source code of Doctrine that outputs the error: here What causes the error? How can I debug where the error comes from?

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  • Using View multiple times in Interface Builder

    - by user1396236
    I'm using a UITableview and have a custom Cell with some labels. I set up all the constraints in Interface Builder. Now I'm using this Cell multiple times, I just copied it in IB. Now it's the time to change some of these contraints because of some bugs (I'm converting a iPhone App to an Universal). But it can't be right that I now have to set the constraints manually for every cell? How do I do right? If I want to control the constraints in one central place, do I have to set them up in Code? I would really not like that! Thanks in advance.

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  • Django - Expression based model constraints

    - by rtmie
    Is it possible to set an expression based constraint on a django model object, e.g. If I want to impose a constraint where an owner can have only one widget of a given type that is not in an expired state, but can have as many others as long as they are expired. Obviously I can do this by overriding the save method, but I am wondering if it can be done by setting constraints, e.g. some derivative of the unique_together constraint WIDGET_STATE_CHOICES = ( ('NEW', 'NEW'), ('ACTIVE', 'ACTIVE'), ('EXPIRED', 'EXPIRED') ) class MyWidget(models.Model): owner = models.CharField(max_length=64) widget_type = models.CharField(max_length = 10) widget_state = models.CharField(max_length = 10, choices = WIDGET_STATE_CHOICES) #I'd like to be able to do something like class Meta: unique_together = (("owner","widget_type","widget_state" != 'EXPIRED')

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  • Why repeat database constraints in models?

    - by BWelfel
    In a CakePHP application, for unique constraints that are accounted for in the database, what is the benefit of having the same validation checks in the model? I understand the benefit of having JS validation, but I believe this model validation makes an extra trip to the DB. I am 100% sure that certain validations are made in the DB so the model validation would simply be redundant. The only benefit I see is the app recognizing the mistake and adjusting the view for the user accordingly (repopulating the fields and showing error message on the appropriate field; bettering the ux) but this could be achieved if there was a constraint naming convention and so the app could understand what the problem was with the save (existing method to do this now?)

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  • Rails 3 respond_with, route constraints and resources

    - by Intelekshual
    I'm building a versioned API, so I have the following nested controllers: ApiController < ApplicationController Api::V1Controller < ApiController Api::V1::EventsController < Api::V1Controller The API is accessed via a subdomain. I have the following routes: constraints(:subdomain => "api") do scope :module => 'api' do namespace :v1 do resources :events end end end This produces the type of URL I want (/v1/events). The problem I'm facing is when using responds_with in Api::V1::EventsController. Just doing something as simple as the below fails with the error too few arguments: def index @events = Event.all respond_with(@events) end I know respond_width is meant to be used with resources, but I'm not sure how the events resource should be accessed from the constrained, scoped, and namespaced route. I can output other things (such as current_user), just not an array of events. Help?

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  • Window sizing constraints by content

    - by EFraim
    I want the window to respect MinWidth/MinHeight and MaxWidth/MaxHeight specifications of the content control inside. Some suggested using SizeToContent, but this only helps to set the initial window size, not the constraints. Others suggested overriding MeasureOverride and setting window's Min/Max height and width there, but this seems to be somewhat unclean, considering that such a trivial problem should surely have a purely declarative solution. Just to mention another solution which seems reasonable but does not work (and had been previously mentioned in an answer which got deleted): binding MinWidth of the window to MinWidth of the control does not take into account window decorations.

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  • xsd.exe creating invalid constraints in dataset from xsd file

    - by Dan Neely
    I have a sequence with an allowed minimum length of zero in my xsd. When I try and load an xml file which doesn't have any elements of the sequence into the DataSet that xsd.exe created I get an exception indicating that my file violated one of the DataSet's constraints. The xml file validates against the schema so I know it's valid. Is there anything I can do to make the tool generate a valid dataset? <xs:sequence minOccurs="0" maxOccurs="unbounded"> <xs:element name="Numbers" type="xs:double"/> </xs:sequence> Edit: if I change my schema to this the generated code works properly. It looks wrong to me though since it appears to be implying that I could have sequence items with nothing in them, which doesn't make any sense. <xs:sequence minOccurs="0" maxOccurs="unbounded"> <xs:element name="Numbers" type="xs:double" minOccurs="0"/> </xs:sequence>

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  • foreign key constraints on primary key columns - issues ?

    - by zzzeek
    What are the pros/cons from a performance/indexing/data management perspective of creating a one-to-one relationship between tables using the primary key on the child as foreign key, versus a pure surrogate primary key on the child? The first approach seems to reduce redundancy and nicely constrains the one-to-one implicitly, while the second approach seems to be favored by DBAs, even though it creates a second index: create table parent ( id integer primary key, data varchar(50) ) create table child ( id integer primary key references parent(id), data varchar(50) ) pure surrogate key: create table parent ( id integer primary key, data varchar(50) ) create table child ( id integer primary key, parent_id integer unique references parent(id), data varchar(50) ) the platforms of interest here are Postgresql, Microsoft SQL Server.

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  • NHibernate not dropping foreign key constraints.

    - by Kendrick
    I'm new to NHibernate, so this is probably my mistake, but when I use: schema.Create(true, true); I get: SchemaExport [(null)]- There is already an object named 'XXX' in the database. System.Data.SqlClient.SqlException: There is already an object named 'XXX' in the database. I grabbed the SQL code nHibernate was using, ran it directly from MSSMS, and recieved similar errors. Looking into it, the generated code is not properly dropping the foreign key constraints. The drop looks like this: if exists (select 1 from sysobjects where id = OBJECT_ID(N'dbo[FK22212EAFBFE4C58]') AND parent_obj = OBJECT_ID('YYY')) alter table dbo.YYY drop constraint FK22212EAFBFE4C58 Doing a "select OBJECT_ID(N'dbo[FK22212EAFBFE4C58]')" I get null. If I take out the "dbo" (i.e. "select OBJECT_ID(N'[FK22212EAFBFE4C58]')") then the ID is returned. So, my question is, why is nHibernate adding the dbo, and why does that prevent the object from being returned (since the table owning the constraint is dbo.XXX) One of my mapping files: <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping namespace="CanineApp.Model" assembly="CanineApp.Model" xmlns="urn:nhibernate-mapping-2.2"> <class name="MedicalLog" table="MedicalLog" schema="dbo"> <id name="MedicalLogID" type="Int64"> <generator class="identity" /> </id> <property name="InvoiceAmount" type="Decimal" not-null="true" /> ... <many-to-one name="Canine" class="Canine" column="CanineID" not-null="true" fetch="join" /> <many-to-one name="TreatmentCategory" class="TreatmentCategory" column="TreatmentCategoryID" not-null="true" access="field.camelcase-underscore" /> </class> </hibernate-mapping>

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  • LINQ To SQL ignore unique constraint exception and continue

    - by Martin
    I have a single table in a database called Users Users ------ ID (PK, Identity) Username (Unique Index) I have setup a unique index on the Username table to prevent duplicates. I am then enumerating through a collection and creating a new user in the database for each item. What I want to do is just insert a new user and ignore the exception if the unique key constraint is violated (as it's clearly a duplicate record in that case). This is to avoid having to craft where not exists kind of queries. First off, is this going to be any more efficient or should my insert code be checking for duplicates instead? I'm drawn more to the database having that logic as this prevents any other type of client from inserting duplicate data. My other issue is related to LINQ To SQL. I have the following code: public class TestRepo { DatabaseDataContext database = new DatabaseDataContext(); public void Add(string username) { database.Users.InsertOnSubmit(new User() { Username = username }); } public void Save() { database.SubmitChanges(); } } And then I iterate over a collection and insert new users, ignoring any exceptions: TestRepo repo = new TestRepo(); foreach (var name in new string[] { "Tim", "Bob", "John" }) { try { repo.Add(name); repo.Save(); } catch { } } The first time this is run, great I have three users in the table. If I remove the second one and run this code again, nothing is inserted. I expected the first insert to fail with the exception, the second to succeed (as I just removed that item from the DB) and the third to then fail. What seems to be happening is that once the SqlException is thrown (even though the loop continues to iterate) all of the next inserts fail - even when there isn't a row in the table that would cause a unique violation. Can anyone explain this? P.S. The only workaround I could find was to instantiate the repo each time before the insert, then it worked exactly as excepted - indicating that it's something to do with the LINQ To SQL DataContext. Thanks.

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  • Using HABTM relationships in cakephp plugins with unique set to false

    - by Dean
    I am working on a plugin for our CakePHP CMS that will handle blogs. When getting to the tags I needed to set the HABTM relationship to unique = false to be able add tags to a post without having to reset them all. The BlogPost model looks like this class BlogPost extends AppModel { var $name = 'BlogPost'; var $actsAs = array('Core.WhoDidIt', 'Containable'); var $hasMany = array('Blog.BlogPostComment'); var $hasAndBelongsToMany = array('Blog.BlogTag' => array('unique' => false), 'Blog.BlogCategory'); } The BlogTag model looks like this class BlogTag extends AppModel { var $name = 'BlogTag'; var $actsAs = array('Containable'); var $hasAndBelongsToMany = array('Blog.BlogPost'); } The SQL error I am getting when I have the unique = true setting in the HABTM relationship between the BlogPost and BlogTag is Query: SELECT `Blog`.`BlogTag`.`id`, `Blog`.`BlogTag`.`name`, `Blog`.`BlogTag`.`slug`, `Blog`.`BlogTag`.`created_by`, `Blog`.`BlogTag`.`modified_by`, `Blog`.`BlogTag`.`created`, `Blog`.`BlogTag`.`modified`, `BlogPostsBlogTag`.`blog_post_id`, `BlogPostsBlogTag`.`blog_tag_id` FROM `blog_tags` AS `Blog`.`BlogTag` JOIN `blog_posts_blog_tags` AS `BlogPostsBlogTag` ON (`BlogPostsBlogTag`.`blog_post_id` = 4 AND `BlogPostsBlogTag`.`blog_tag_id` = `Blog`.`BlogTag`.`id`) As you can see it is trying to set the blog_tags table to 'Blog'.'BlogTag. which isn't a valid MySQL name. When I remove the unique = true from the relationship it all works find and I can save one tag but when adding another it just erases the first one and puts the new one in its place. Does anyone have any ideas? is it a bug or am I just missing something? Cheers, Dean

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