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  • Linq to Entities and outer joins issue

    - by Robert Koritnik
    Can somebody tell me, why does Linq to Entities translate many to 1 relationships to left outer joins instead of inner joins? It relation was many to 0..1. There's referential constraint on DB itself, that ensures there's a record in the right table, so inner join should be used instead. Is it possible to write LINQ in a way so they will translate to inner joins rather than left outer joins. It would speed query execution a lot.

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  • 'Contains()' workaround using Linq to Entities?

    - by jbloomer
    I'm trying to create a query which uses a list of ids in the where clause, using the Silverlight ADO.Net Data Services client api (and therefore Linq To Entities). Does anyone know of a workaround to Contains not being supported? I want to do something like this: List<long?> txnIds = new List<long?>(); // Fill list var q = from t in svc.OpenTransaction where txnIds.Contains(t.OpenTransactionId) select t;

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  • Stored Functions with Linq to Entities

    - by Lawnmower
    Hi, How can I make a MS-SQL stored function availabe in LINQ expressions if using the Entity framework? The SQL function was created with CREATE FUNCTION MyFunction(@name) ...). I was hoping to access it similarly to this: var data = from c in entities.Users where MyFunction(c.name) = 3; Unfortunately I have only .NET 3.5 available.

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  • Implement LINQ to Entities unsupported method

    - by Dan
    Hi! LINQ to Entities has many LINQ methods marked as "Unsupported" (http://msdn.microsoft.com/en-us/library/bb738550.aspx). Is any way to implement some of these methods by hands? Or I should wait next release of EF? I'm especially needing this method: IQueryable<TResult> Select<TSource, TResult>(this IQueryable<TSource> source, Expression<Func<TSource, int, TResult>> selector) Thanks

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  • Using NHibernate to select entities based on activity of children entities

    - by mannish
    I'm having a case of the Mondays... I need to select blog posts based on recent activity in the post's comments collection (a Post has a List<Comment> property and likewise, a Comment has a Post property, establishing the relationship. I don't want to show the same post twice, and I only need a subset of the entities, not all of the posts. First thought was to grab all posts that have comments, then order those based on the most recent comment. For this to work, I'm pretty sure I'd have to limit the comments for each Post to the first/newest Comment. Last I'd simply take the top 5 (or whatever max results number I want to pass into the method). Second thought would be to grab all of the comments, ordered by CreatedOn, and filter so there's only one Comment per Post. Then return those top (whatever) posts. This seems like the same as the first option, just going through the back door. I've got an ugly, two query option I've got working with some LINQ on the side for filtering, but I know there's a more elegant way to do it in using the NHibernate API. Hoping to see some good ideas here.

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  • What's a good entity hierarchy for a 2D game?

    - by futlib
    I'm in the process of building a new 2D game out of some code I wrote a while ago. The object hierarchy for entities is like this: Scene (e.g. MainMenu): Contains multiple entities and delegates update()/draw() to each Entity: Base class for all things in a scene (e.g. MenuItem or Alien) Sprite: Base class for all entities that just draw a texture, i.e. don't have their own drawing logic Does it make sense to split up entities and sprites up like that? I think in a 2D game, the terms entity and sprite are somewhat synonymous, right? But I do believe that I need some base class for entities that just draw a texture, as opposed to drawing themselves, to avoid duplication. Most entities are like that. One weird case is my Text class: It derives from Sprite, which accepts either the path of an image or an already loaded texture in its constructor. Text loads a texture in its constructor and passes that to Sprite. Can you outline a design that makes more sense? Or point me to a good object-oriented reference code base for a 2D game? I could only find 3D engine code bases of decent code quality, e.g. Doom 3 and HPL1Engine.

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  • LINQ to Entities for subtracting 2 dates

    - by Michael I
    I am trying to determine the number of days between 2 dates using LINQ with Entity Framework. It is telling me that it does not recognize Subtract on the System.TimeSpan class Here is my where portion of the LINQ query. where ((DateTime.Now.Subtract(vid.CreatedDate).TotalDays < maxAgeInDays)) Here is the error I receive in the VS.NET debugger {"LINQ to Entities does not recognize the method 'System.TimeSpan Subtract(System.DateTime)' method, and this method cannot be translated into a store expression."} Am I doing something wrong or is there a better way to get the number of days between 2 DateTimes in the entity framework? thanks Michael

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  • Linq to Entities : using ToLower() on NText fields

    - by Julien N
    I'm using SQL Server 2005, with a case sensitive database.. In a search function, I need to create a Linq To Entities (L2E) query with a "where" clause that compare several strings with the data in the database with these rules : The comparison is a "Contains" mode, not strict compare : easy as the string's Contains() method is allowed in L2E The comparison must be case insensitive : I use ToLower() on both elements to perform an insensitive comparison. All of this performs really well but I ran into the following Exception : "Argument data type ntext is invalid for argument 1 of lower function" on one of my fields. It seems that the field is a NText field and I can't perform a ToLower() on that. What could I do to be able to perform a case insensitive Contains() on that NText field ?

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  • LiNQ to Entities, Include less

    - by Freddy
    Hi, If you are making a LinQ to entities expression for ClassA where A has a relation to ClassB like this: var temp = from p in myEntities.ClassA.Include("ClassB") where ... select p; You will get a set of ClassA:s with the reference to ClassB loaded. The thing in my case is that I dont really need to load ALL the ClassB-references, just a few of them. But I dont want to loop through the list of ClassA:s and load them individually, i want my database operations to be fewer and bigger instead of reading small chunks here and there. Is it possible to put some kind of restrictions on which references to include or do you have to accept this all or nothing style?

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  • SQL's Rownumber with Linq-to-entities

    - by mariki
    I am converting my project to use EF and also want to covert stored procedures into Linq-to-entities queries. This my SQL query (simple version) that I have trouble to convert: SELECT CategoryID, Title as CategoryTitle,Description, LastProductTitle,LastProductAddedDate FROM ( SELECT C.CategoryID, C.Title,C.Description, C.Section, P.Title as LastProductTitle, P.AddedDate as LastProductAddedDate, ROW_NUMBER() OVER (PARTITION BY P.CategoryID ORDER BY P.AddedDate DESC) AS Num FROM Categories C LEFT JOIN Products P ON P.CategoryID = C.CategoryID ) OuterSelect WHERE OuterSelect.Num = 1 In words: I want to return all Categories (from Categories table) and title and date of addition of the product (from Products table) that was added last to this category. How can I achieve this using Entity frame work query? In most efficient way.

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  • Defaultifempty seems to work in linq to entities

    - by Rand
    I'm new to linq and linq to entities so I might have gone wrong in my assumptions, but I've been unknowingly trying to use DefaultIfEmpty in L2E. For some reason if I turn the resultset into a List, the Defaultifempty() works I don't know if I've inadvertantly crossed over into Linq area. The code below works, can anyone tell me why? And if it does work great, then it'll be of help to other people. var results = (from u in rv.tbl_user .Include("tbl_pics") .Include("tbl_area") .Include("tbl_province") .ToList() where u.tbl_province.idtbl_Province == prov select new { u.firstName, u.cellNumber, u.tbl_area.Area, u.ID,u.tbl_province.Province_desc, pic = (from p3 in u.tbl_pics where p3.tbl_user.ID == u.ID select p3.pic_path).DefaultIfEmpty("defaultpic.jpg").First() }).ToList();

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  • Linq to Entities and LEFT OUTER JOIN issue with MANY:1 relations

    - by Robert Koritnik
    Can somebody tell me, why does Linq to Entities translate many to 1 relationships to left outer join instead of inner join? Because there's referential constraint on DB itself that ensures there's a record in the right table, so inner join should be used instead (and it would work much faster) If relation was many to 0..1 left outer join would be correct. Question Is it possible to write LINQ in a way so it will translate to inner join rather than left outer join. It would speed query execution a lot... I haven't used eSQL before, but would it be wise to use it in instead of LINQ? Edit I updated my tags to include technology I'm using in the background: Entity Framework V1 Devart dotConnect for Mysql MySql database If someone could test if the same is true on Microsoft SQL server it would also give me some insight if this is Devart's issue or it's a general L2EF functionality... But I suspect EF is the culprit here.

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  • Binding Linq To Entities query results to a datagridview

    - by Nickson
    I just started playing with Linq to entities in a windows forms application and am not understanding one behavior that looks so simple though. If i type code below, i get ReadOnly records in my dataGridView Dim x = From n in Table1 _ Select n.FirstName, n.LastName, N.Department DataGridView1.DataSource = x But if i type the following code, i get editable rows in my dataGridView Dim x = From n in Table1 _ Select n DataGridView1.DataSource = x So, basically if i specify the column names to select and databind to my DataGridView1, the rows are readonly but if i do not specify the column names and databind to the DataGridView, the rows are editable and i don't understand why.

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  • Linq to Entities - left Outer Join

    - by user255234
    Could you please help me to figure this one out? I need to replace a join with OSLP table with OUTER join. Seems a bit tricky for someone who is not an expert in Linq to entities. How would I do that? var surgeonList = ( from item in context.T1_STM_Surgeon .Include("T1_STM_SurgeonTitle") .Include("OTER") where item.ID == surgeonId join reptable in context.OSLP on item.Rep equals reptable.SlpCode select new { ID = item.ID, First = item.First, Last = item.Last, Rep = reptable.SlpName, Reg = item.OTER.descript, PrimClinic = item.T1_STM_ClinicalCenter.Name, Titles = item.T1_STM_SurgeonTitle, Phone = item.Phone, Email = item.Email, Address1 = item.Address1, Address2 = item.Address2, City = item.City, State = item.State, Zip = item.Zip, Comments = item.Comments, Active = item.Active, DateEntered = item.DateEntered }).ToList(); Thanks in advance!!

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  • Linq to Entities performance within ASP.NET Development Server

    - by tster
    I've been evaluating linq to entities and linq to SQL for a project. Obviously each has its own advantages and disadvantages which have been discussed plenty of times here. However, One thing I am seeing with L2E is kind of odd. Using L2S, when using the ASP.NET Development Server, the performance is a little slower for my web service calls. I'm looking at 300ms vs. 250 ms. However, when using L2E, when using ASP.NET Dev Server, the performance is awful. I'm talking 1,250 ms vs. 220 ms. I know I should probably just use local IIS for development, but I'm curious if anyone else has seen this, or knows what is causing it.

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  • How to substr html entities properly?

    - by Emily
    Hi everyone. I have like this : $mytext="that&#039;s really &quot;confusing&quot; and &lt;absolutly&gt; silly"; echo substr($mytext,0,6); The output in this case will be : that&# instead of that's What i want is to count html entities as 1 character then substr, because i always end up with breaked html or some obscure characters at the end of text. Please don't suggest me to html decode it then substr then encode it, i want a clean method :) Thanks

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  • Entity Framework: Delete Object and its related entities

    - by Waheed
    Hi, Does anyone know how to delete an object and all of it's related entities. For example i have tables, Products, Category, ProductCategory and productDetails, the productCategory is joining table of both Product and Category. I have red from http://msdn.microsoft.com/en-us/library/bb738580.aspx that Deleting the parent object also deletes all the child objects in the constrained relationship. This result is the same as enabling the CascadeDelete property on the association for the relationship. I am using this code Product productObj = this.ObjectContext.Product.Where(p => p.ProductID.Equals(productID)).First(); if (!productObj.ProductCategory.IsLoaded) productObj.ProductCategory.Load(); if (!productObj.ProductDetails.IsLoaded) productObj.ProductDetails.Load(); //my own methods. base.Delete(productObj); base.SaveAllObjectChanges(); But i am getting error on ObjectContext.SaveChanges(); i.e A relationship is being added or deleted from an AssociationSet 'FK_ProductCategory_Product'. With cardinality constraints, a corresponding 'ProductCategory' must also be added or deleted. Thanks in advance....

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  • Should the entity framework + self tracking entities be saving me time

    - by sipwiz
    I've been using the entity framework in combination with the self tracking entity code generation templates for my latest silverlight to WCF application. It's the first time I've used the entity framework in a real project and my hope was that I would save myself a lot of time and effort by being able to automatically update the whole data access layer of my project when my database schema changed. Happily I've found that to be the case, updating my database schema by adding a new table, changing column names, adding new columns etc. etc. can be propagated to my business object classes by using the update from database option on the entity framework model. Where I'm hurting is the CRUD operations within my WCF service in response to actions on my Silverlight client. I use the same self tracking entity framework business objects in my Silverlight app but I find I'm continually having to fight against problems such as foreign key associations not being handled correctly when updating an object or the change tracker getting confused about the state of an object at the Silverlight end and the data access operation within the WCF layer throwing a wobbly. It's got to a point where I have now spent more time dealing with this quirks than I have on my previous project where I used Linq-to-SQL as the starting point for rolling my own business objects. Is it just me being hopeless or is the self tracking entities approach something that should be avoided until it's more mature?

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  • Linq to Entities custom ordering via position mapping table

    - by Bigfellahull
    Hi, I have a news table and I would like to implement custom ordering. I have done this before via a positional mapping table which has newsIds and a position. I then LEFT OUTER JOIN the position table ON news.newsId = position.itemId with a select case statement CASE WHEN [position] IS NULL THEN 9999 ELSE [position] END and order by position asc, articleDate desc. Now I am trying to do the same with Linq to Entities. I have set up my tables with a PK, FK relationship so that my News object has an Entity Collection of positions. Now comes the bit I can't work out. How to implement the LEFT OUTER JOIN. I have so far: var query = SelectMany (n => n.Positions, (n, s) => new { n, s }) .OrderBy(x => x.s.position) .ThenByDescending(x => x.n.articleDate) .Select(x => x.n); This kinda works. However this uses a INNER JOIN so not what I am after. I had another idea: ret = ret.OrderBy(n => n.ShufflePositions.Select(s => s.position)); However I get the error DbSortClause expressions must have a type that is order comparable. I also tried ret = ret.GroupJoin(tse.ShufflePositions, n => n.id, s => s.itemId, (n, s) => new { n, s }) .OrderBy(x => x.s.Select(z => z.position)) .ThenByDescending(x => x.n.articleDate) .Select(x => x.n); but I get the same error! If anyone can help me out, it would be much appreciated!

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  • Linq to Entities Joins

    - by Bob Avallone
    I have a question about joins when using Linq to Entities. According to the documentation the use on the join without a qualifier performs like a left outer join. However when I execute the code below, I get a count returned of zero. But if I comment out the three join lines I get a count of 1. That would indicate that the join are acting as inner join. I have two questions. One which is right inner or outer as the default? Second how do I do the other one i.e. inner or outer? The key words on inner and outer do not work. var nprs = (from n in db.FMCSA_NPR join u in db.FMCSA_USER on n.CREATED_BY equals u.ID join t in db.LKUP_NPR_TYPE on n.NPR_TYPE_ID equals t.ID join s in db.LKUP_AUDIT_STATUS on n.NPR_STATUS_ID equals s.ID where n.ROLE_ID == pRoleId && n.OWNER_ID == pOwnerId && n.NPR_STATUS_ID == pNPRStatusId && n.ACTIVE == pActive select n).ToList(); if (nprs.Count() == 0) return null;

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  • PHP - DOM class - numbered entities and encodings problem

    - by user343607
    Hi guys, I'm having some difficult with PHP DOM class. I am making a sitemap script, and I need the output of $doc-saveXML() to be like <?xml version="1.0" encoding="UTF-8"?> <root> <url> <loc>http://www.somesite.com/servi&#xE7;os/redesign</loc> </url> </root> or <?xml version="1.0" encoding="UTF-8"?> <root> <url> <loc>http://www.somesite.com/servi&#231;os/redesign</loc> </url> </root> but I am getting: <?xml version="1.0" encoding="UTF-8"?> <root> <url> <loc>http://www.somesite.com/servi&amp;#xE7;os/redesign</loc> </url> </root> This is the closet I could get, using a replace named to numbered entities function. I was also able to reproduce <?xml version="1.0" ?> <root> <url> <loc>http://www.somesite.com/servi&amp;#xE7;os/redesign</loc> </url> </root> But without the encoding specified. The best solution (the way I think the code should be written) would be: <?php $myArray = array(); // do some stuff to populate the with URL strings $doc = new DOMDocument('1.0', 'UTF-8'); // here we modify some property. Maybe is the answer I am looking for... $urlset = doc->createElement("urlset"); $urlset = $doc->appendChild($urlset); foreach($myArray as $address) { $url = $doc->createElement("url"); $url = $urlset->appendChild($url); $loc = $doc->createElement("loc"); $loc = $url->appendChild($loc); $valueContent = $doc->createTextNode($value); $valueContent = $loc->appendChild($address); } echo $doc->saveXML(); ?> Notes: Server response header contains charset as UTF-8; PHP script is saved in UTF-8; URLs read are UTF-8 strings; Above script contains encoding declaration on DOMDocument constructor, and does not use any convert functions, like htmlentities, urlencode, utf8_encode... I've tried changing the DOMDocument properties DOMDocument::$resolveExternals and DOMDocument::$substituteEntities values. None combinations worked. And yes, I know I can made all process without specifying the character set on DOMDocument constructor, dump string content into a variable and make a very simple string substitution with string replace functions. This works. But I would like to know where I am slipping, how can this be made using native API's and settings, or even if this is possible. Thanks in advance.

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  • Initializing entities vs having a constructor parameter

    - by Vee
    I'm working on a turn-based tile-based puzzle game, and to create new entities, I use this code: Field.CreateEntity(10, 5, Factory.Player()); This creates a new Player at [10; 5]. I'm using a factory-like class to create entities via composition. This is what the CreateEntity method looks like: public void CreateEntity(int mX, int mY, Entity mEntity) { mEntity.Field = this; TileManager.AddEntity(mEntity, true); GetTile(mX, mY).AddEntity(mEntity); mEntity.Initialize(); InvokeOnEntityCreated(mEntity); } Since many of the components (and also logic) of the entities require to know what the tile they're in is, or what the field they belong to is, I need to have mEntity.Initialize(); to know when the entity knows its own field and tile. The Initialize(); method contains a call to an event handler, so that I can do stuff like this in the factory class: result.OnInitialize += () => result.AddTags(TDLibConstants.GroundWalkableTag, TDLibConstants.TrapdoorTag); result.OnInitialize += () => result.AddComponents(new RenderComponent(), new ElementComponent(), new DirectionComponent()); This works so far, but it is not elegant and it's very open to bugs. I'm also using the same idea with components: they have a parameterless constructor, and when you call the AddComponent(mComponent); method in an entity, it is the entity's job to set the component's entity to itself. The alternative would be having a Field, int, int parameters in the factory class, to do stuff like: new Entity(Field, 10, 5); But I also don't like the fact that I have to create new entities like this. I would prefer creating entities via the Field object itself. How can I make entity/component creation more elegant and less prone to bugs?

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