Entity Framework 6 - Knowledge Base (KB)
839 results in tag: linq
Expression. How do I invoke Entity Framework?
The Entity Framework does not support the ...Expression.Invoke... operator. You receive the following exception when trying to use it:..."The LINQ expression node type 'Invoke' is not supported in LINQ to Entities....Has anyone got a workaround for this ...
asked by Brad Leach
Building where clauses to evaluate collections inside a many to many connection using LINQ to entities
So, I am using the Linq entity framework. I have 2 entities: ...Content... and ...Tag.... They are in a many-to-many relationship with one another. ...Content... can have many ...Tags... and ...Tag... can have many ...Contents.... So I am trying to write ...
asked by Phobis
What are some alternatives to expanding in a LINQ to ADO.net Data Service query?
I am wondering if there are any alternatives to using the Expand key word when performing an LINQ to ADO.net Data Services query. The expand method does get me the data I am interested in, but it requires me to know all of the sub-objects that I am going...
asked by ChrisHDog
What is the best way to create a Linq Expression Tree that compares to a generic object?
I have an IQueryable and an object of type T....I want to do IQueryable().Where(o => o.GetProperty(fieldName) == objectOfTypeT.GetProperty(fieldName))...so ......public IQueryable<T> DoWork<T>(string fieldName) where T : EntityObject { ... T...
asked by JTew
How can I utilize LINQ to Entities with a WPF TreeView HierarchicalDataTemplate?
I've got a Page class in my .edmx ADO.NET Entity Data Model file with with Parent and Children properties. It's for a hierarchy of Pages....removed dead ImageShack link - ADO.NET Entity Framework Hierarchical Page Class...This is handled in my SQL databa...
asked by Zack Peterson
TreeView Binding in WPF
I've got a class with Parent and Children properties....ADO.NET Entity Framework Hierarchical Page Class http://img148.imageshack.us/img148/6802/edmxxe8.gif...I want to display this hierarchy in a WPF treeview....Here's my XAML......<TreeView Margin="12" ...
asked by Zack Peterson
Within a generic extension method, how do I apply OrderBy to an IQueryable using a string column name?
public static IQueryable<TResult> ApplySortFilter<T, TResult>(this IQueryable<T> query, string columnName) where T : EntityObject { var param = Expression.Parameter(typeof(T), "o"); var body = Expression.PropertyOrField(param,columnName); var sor...
asked by JTew
With Linq to Entity, how do I obtain the maximum ID?
I have a table User which has an identity column ...UserID..., now what is the correct Linq to Entity line of code that would return me the max ...UserID...?...I've tried:...using (MyDBEntities db = new MyDBEntities()) { var User = db.Users.Last(); ...
asked by Ray
Group Optimization In LINQ to Entities, by
I have this query in LINQ to Entities.... var query = (from s in db.ForumStatsSet where s.LogDate >= date1 && s.LogDate <= date2 group s by new { s.Topic.topicID, s.Topic.subject, s.Topic.Forum.forumName, s...
asked by Olaj
Entity Framework unit testing
I want to test my Entities that are built using Entity Framework. My concern is that using Entity Framework means directly working with data source. So any ideas how to unit testing Entity Framework based components?
asked by Muhammad Soliman
If Contains isn't supported, how can you make a SQL-style 'IN' query in LINQ to Entities (Entity Framework)?
I'm using LINQ to Entities (not LINQ to SQL) and I'm having trouble creating an 'IN' style query. Here is my query at the moment:...var items = db.InventoryItem .Include("Kind") .Include("PropertyValues") ....
asked by JC Grubbs
Using Linq to Entities as a workaround for 'Contains()'?
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 ...
asked by James Bloomer
In LinQ-to-Entities, adding to the Where clause of an Update
Let's say I have a table called Product, with three columns: Id, CustomerId, Name. Id is the primary key. The schema is outside of the control of my group, and we now have a requirement to always provide CustomerId as a parameter for all queries (selects...
asked by Joel Martinez
Entity Framework Join and Include
I have the following query of linq to entities. The problem is that it doesn't seem to load the "Tags" relation even though i have included a thing for it. It works fine if i do not join on tags but i need to do that.... var items = from i in d...
asked by Olaj
Which book is the best for learning Linq, especially Linq to Entities?
I heard lots of reviews on the book Linq in Action, but it does not cover Linq to Entities. ... Please provide your feedback on the books you may have read.
asked by Binoj Antony
To pick an anonymous type, establish a LINQ Expression Tree.
I would like to generate the following select statement dynamically using expression trees:...var v = from c in Countries where c.City == "London" select new {c.Name, c.Population}; ...I have worked out how to generate...var v = from c in ...
asked by Tom Deloford
Updating your edmx to reflect database changes (.net linq-to-entities)
So I have my edmx made. ...Then I change my database a little bit, changing a column to from being a NOT NULL to allowing NULL....I go into my edmx, right click and choose "Update Model from Database"...Now I go into my program and it hasnt actually upda...
asked by Stuck In Baghdad
Include() function of Linq-to-Entities is not loading
If I use a join, the Include() method is no longer working, eg:...from e in dc.Entities.Include("Properties") join i in dc.Items on e.ID equals i.Member.ID where (i.Collection.ID == collectionID) select e ...e.Properties... is not loaded...Without the jo...
asked by Lee Atkinson
In LINQ to Entities, creating a context
I've seen two different manners that programmers approach when creating an entity context in their code....The first is like such, and you can find it all over the MSDN code examples:...public void DoSomething() { using (TaxableEducationEntities cont...
asked by Jagd
LINQ to Entities bulk deletion
Is there any way to bulk-delete a bunch of objects matching a given query in LINQ or LINQ-to-Entities? The only references that I can find are outdated, and it seems silly to iterate over and manually delete all objects I wish to remove.
asked by Benjamin Pollack
