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  • entity framework inserting a many-to-many relationship between two existing objects while updating

    - by redbluegreen
    I'm trying to do this: using(var context = new SampleEntities()) { User user = select a user from database; //Update user's properties user.Username = ... user.Website = ... //Add a role Role role = select a role from database //trying to insert into table UserRoles which has columns (UserID, RoleID) user.Roles.Add(role); //Apply property changes context.ApplyPropertyChanges("Users", user); context.SaveChanges(); } However, I get an exception telling me that "The existing object in the ObjectContext is in the Added state" and can't "ApplyPropertyChanges". If "ApplyPropertyChanges()" is removed, it adds a User. What orders should these methods be called? I don't need to do them separately right? Thanks.

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  • ADO.NET Entity Framework: Can I have multiple entity types for the same row.

    - by black_nm
    Hi all, I have a base class Participants inherited by Artist, Author and TextWriter. I have only one table in the data store: Participants { ID, FirstName, LastName, IsArtist, IsAuthor, IsTextWriter, } The idea is to have a class for all the roles that a participant can have. I've managed to create the edmx file but when I try to get an Participant (as Artist) that is also an Author I receive the following error: All objects in the EntitySet 'Participants' must have unique primary keys. However, an instance of type 'Artist' and an instance of type 'Author' both have the same primary key value, 'EntitySet=Participants;ID=1'. Thank you

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  • Fixing up an entity framework query

    - by vdh_ant
    My table structure is as follows: Person 1-M PesonAddress Person 1-M PesonPhone Person 1-M PesonEmail Person 1-M Contract Contract M-M Program Contract M-1 Organization At the end of this query I need a populated object graph where each person has their: PesonAddress's PesonPhone's PesonEmail's PesonPhone's Contract's - and this has its respective Program's Now I had the following query and I thought that it was working great, but it has a couple of problems: from people in ctx.People.Include("PersonAddress") .Include("PersonLandline") .Include("PersonMobile") .Include("PersonEmail") .Include("Contract") .Include("Contract.Program") where people.Contract.Any( contract => (param.OrganizationId == contract.OrganizationId) && contract.Program.Any( contractProgram => (param.ProgramId == contractProgram.ProgramId))) select people; The problem is that it filters the person to the criteria but not the Contracts or the Contract's Programs. It brings back all Contracts that each person has not just the ones that have an OrganizationId of x and the same goes for each of those Contract's Programs respectively. What I want is only the people that have at least one contract with an OrgId of x with and where that contract has a Program with the Id of y... and for the object graph that is returned to have only the contracts that match and programs within that contract that match. I kinda understand why its not working, but I don't know how to change it so it is working... This is my attempt thus far: from people in ctx.People.Include("PersonAddress") .Include("PersonLandline") .Include("PersonMobile") .Include("PersonEmail") .Include("Contract") .Include("Contract.Program") let currentContracts = from contract in people.Contract where (param.OrganizationId == contract.OrganizationId) select contract let currentContractPrograms = from contractProgram in currentContracts let temp = from x in contractProgram.Program where (param.ProgramId == contractProgram.ProgramId) select x where temp.Any() select temp where currentContracts.Any() && currentContractPrograms.Any() select new Person { PersonId = people.PersonId, FirstName = people.FirstName, ..., ...., MiddleName = people.MiddleName, Surname = people.Surname, ..., ...., Gender = people.Gender, DateOfBirth = people.DateOfBirth, ..., ...., Contract = currentContracts, ... }; //This doesn't work But this has several problems (where the Person type is an EF object): I am left to do the mapping by myself, which in this case there is quite a lot to map When ever I try to map a list to a property (i.e. Scholarship = currentScholarships) it says I can't because IEnumerable is trying to be cast to EntityCollection Include doesn't work Hence how do I get this to work. Keeping in mind that I am trying to do this as a compiled query so I think that means anonymous types are out.

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  • Mapped Stored Procedures in EF 1

    - by michael.lukatchik
    All, I'm using mapped Stored Procedures in EF 1. I've completed the following steps: 1) I've created my INSERT, UPDATE, and DELETE queries in SQL Server. 2) I've built the EDMX and imported the INSERT, UPDATE, and DELETE sprocs as part of my model. 3) I've set up a Stored Procedure Mapping on a table inside of my EDMX file. The INSERT, UPDATE, and DELETE sprocs were mapped accordingly. Using this approach, I would expect to rebuild the application (and mine builds successfully) and then see the Stored Procedures as available function names via my EDMX object, such as: _entities.InsertComment(..), _entities.UpdateComment(..), and _entities.DeleteComment(..) Intellisense is not picking these names up and I can't figure out why. If I perform these same steps using EF4, the function names are automatically picked up by Intellisense after adding the Stored Procedure Mappings. Is this a bug in EF1? Is there something else I should be doing? Thanks in advance, Mike

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  • entity framework - getting null exception using foreign key

    - by Nick
    Having some trouble with what should be a very simple scenario. For example purposes, I have two tables: -Users -Comments There is a one-to-many relationship set up for this; there is a foreign key from Comments.CommentorID to Users.UserID. When I do the LINQ query and try to bind to a DataList, I get a null exception. Here is the code: FKMModel.FKMEntities ctx = new FKMModel.FKMEntities(); IQueryable<Comment> CommentQuery = from x in ctx.Comment where x.SiteID == 101 select x; List<Comment> Comments = CommentQuery.ToList(); dl_MajorComments.DataSource = Comments; dl_MajorComments.DataBind(); In the ASPX page, I have the following as an ItemTemplate (I simplified it and took out the styling, etc, for purposes of posting here since it's irrelevant): <div> <%# ((FKMModel.Comment)Container.DataItem).FKMUser.Username %> <%# ((FKMModel.Comment)Container.DataItem).CommentDate.Value.ToShortDateString() %> <%# ((FKMModel.Comment)Container.DataItem).CommentTime %> </div> The exception occurs on the first binding (FKMUser.Username). Since the foreign key is set up, I should have no problem accessing any properties from the Users table. Intellisense set up the FKMUser navigation property and it knows the properties of that foreign table. What is going on here??? Thanks, Nick

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  • Using Entity Framework (code first) migrations in production

    - by devdigital
    I'm just looking into using EF migrations for our project, and in particular for performing schema changes in production between releases. I can see that generating SQL (delta) script files is an option, but is there no way of running the migrations programmatically on app start up? Will I instead need to add each delta script to the solution and write my own framework to apply them in order (from the current version to the latest) on bootstrap?

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  • Why should I use Entity Framework over Linq2SQL ...

    - by Refracted Paladin
    To be clear, I am not asking for a side by side comparision which has already been asked Ad Nauseum here on SO. I am also Not asking if Linq2Sql is dead as I don't care. What I am asking is this.... I am building internal apps only for a non-profit organization. I am the only developer on staff. We ALWAYS use SQL Server as our Database backend. I design and build the Databases as well. I have used L2S successfully a couple of times already. Taking all this into consideration can someone offer me a compelling reason to use EF instead of L2S? I was at Code Camp this weekend and after an hour long demonstration on EF, all of which I could have done in L2S, I asked this same question. The speakers answer was, "L2S is dead..." Very well then! NOT! (see here) I understand EF is what MS WANTS us to use in the future(see here) and that it offers many more customization options. What I can't figure out is if any of that should, or does, matter for me in this environment. One particular issue we have here is that I inherited the Core App which was built on 4 different SQL Data bases. L2S has great difficulty with this but when I asked the aforementioned speaker if EF would help me in this regard he said "No!"

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  • Entity Framework - refresh objects from database

    - by Nebo
    I'm having trouble with refreshing objects in my database. I have an two PC's and two applications. On the first PC, there's an application which communicates with my database and adds some data to Measurements table. On my other PC, there's an application which retrives the latest Measurement under a timer, so it should retrive measurements added by the application on my first PC too. The problem is it doesn't. On my application start, it caches all the data from database and never get new data added. I use Refresh() method which works well when I change any of the cached data, but it doesn't refresh newly added data. Here is my method which should update the data: public static Entities myEntities = new Entities(); public static Measurement GetLastMeasurement(int conditionId) { myEntities.Refresh(RefreshMode.StoreWins, myEntities.Measurements); return (from measurement in myEntities.Measurements where measurement.ConditionId == conditionId select measurement).OrderByDescending(cd => cd.Timestamp).First(); } P.S. Applications have different connection strings in app.config (different accounts for the same DB).

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  • Using DateDiff in Entity Framwork on a SQL CE database

    - by deverop
    I have a method which should return a list of anonymous objects with a calculated column like this: var tomorrow = DateTime.Today.AddDays(1); return from t in this.Events where (t.StartTime >= DateTime.Today && t.StartTime < tomorrow && t.EndTime.HasValue) select new { Client = t.Activity.Project.Customer.Name, Project = t.Activity.Project.Name, Task = t.Activity.Task.Name, Rate = t.Activity.Rate.Name, StartTime = t.StartTime, EndTime = t.EndTime.Value, Hours = (System.Data.Objects.SqlClient.SqlFunctions.DateDiff("m", t.StartTime, t.EndTime.Value) / 60), Description = t.Activity.Description }; Unfortunately I get the following error from the DateDiff function: The specified method 'System.Nullable1[System.Int32] DateDiff(System.String, System.Nullable1[System.DateTime], System.Nullable`1[System.DateTime])' on the type 'System.Data.Objects.SqlClient.SqlFunctions' cannot be translated into a LINQ to Entities store expression. Any ideas what I could have done wrong here? EDIT: I also tried the EntityFunctions class mentioned here, but that did not work as well. Minutes = EntityFunctions.DiffMinutes(t.EndTime, t.StartTime),

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  • How to bind gridview using linq/Entity Framework?

    - by Kay
    I need to bind GridView, I am using this code: ProductDBEntities db = new ProductPDBEntities(); var pro = from u in db.Products where u.PID == 1 select u; if (pro != null) { GridView1.DataSource = pro; GridView1.DataBind(); } and getting this error. System.InvalidOperationException: Sequence contains more than one element Can somebody please tell me what am I doin wrong?

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  • Creating base class for Entities in Entity Framework

    - by Thomas
    I would like to create a base class that is somewhat generic for all of my entities. The class would have methods like Save(), Delete(), GetByID() and some other basic functionality and properties. I have more experience with Linq to SQL and was hoping to get some good examples for something similar in the EF. Thank you.

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  • Why use Entity Framework over Linq2SQL ...

    - by Refracted Paladin
    To be clear, I am not asking for a side by side comparision which has already been asked Ad Nauseum here on SO. I am also Not asking if Linq2Sql is dead as I don't care. What I am asking is this.... I am building internal apps only for a non-profit organization. I am the only developer on staff. We ALWAYS use SQL Server as our Database backend. I design and build the Databases as well. I have used L2S successfully a couple of times already. Taking all this into consideration can someone offer me a compelling reason to use EF instead of L2S? I was at Code Camp this weekend and after an hour long demonstration on EF, all of which I could have done in L2S, I asked this same question. The speakers answer was, "L2S is dead..." Very well then! NOT! (see here) I understand EF is what MS WANTS us to use in the future(see here) and that it offers many more customization options. What I can't figure out is if any of that should, or does, matter for me in this environment. One particular issue we have here is that I inherited the Core App which was built on 4 different SQL Data bases. L2S has great difficulty with this but when I asked the aforementioned speaker if EF would help me in this regard he said "No!"

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  • How to get IQueryable<> from stored procedure (entity framework)

    - by mmcteam
    I want to get IQueryable<> result when executing stored procedure. Here is peace of code that works fine: IQueryable<SomeEntitiy> someEntities; var globbalyFilteredSomeEntities = from se in m_Entities.SomeEntitiy where se.GlobalFilter == 1234 select se; I can use this to apply global filter, and later use result in such way result = globbalyFilteredSomeEntities .OrderByDescending(se => se.CreationDate) .Skip(500) .Take(10); What I want to do - use some stored procedures in global filter. I tried: Add stored procedure to m_Entities, but it returns IEnumerable<> and executes sp immediately: var globbalyFilteredSomeEntities = from se in m_Entities.SomeEntitiyStoredProcedure(1234); Materialize query using EFExtensions library, but it is IEnumerable<>. If I use AsQueryable() and OrderBy(), Skip(), Take() and after that ToList() to execute that query - I get exception that DataReader is open and I need to close it first(can't paste error - it is in russian). var globbalyFilteredSomeEntities = m_Entities.CreateStoreCommand("exec SomeEntitiyStoredProcedure(1234)") .Materialize<SomeEntitiy>(); //.AsQueryable() //.OrderByDescending(se => se.CreationDate) //.Skip(500) //.Take(10) //.ToList(); Also just skipping .AsQueryable() is not helpful - same exception.

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  • .Net Entity Framework & POCO ... querying full table problem

    - by Chris Klepeis
    I'm attempting to implement a repository pattern with my poco objects auto generated from my edmx. In my repository class, I have: IObjectSet<E> _objectSet; private IObjectSet<E> objectSet { get { if (_objectSet == null) { _objectSet = this._context.CreateObjectSet<E>(); } return _objectSet; } } public IQueryable<E> GetQuery(Func<E, bool> where) { return objectSet.Where(where).AsQueryable<E>(); } public IList<E> SelectAll(Func<E, bool> where) { return GetQuery(where).ToList(); } Where E is the one of my POCO classes. When I trace the database and run this: IList<Contact> c = contactRepository.SelectAll(r => r.emailAddress == "[email protected]"); It shows up in the sql trace as a select for everything in my Contact table. Where am I going wrong here? Is there a better way to do this? Does an objectset not lazy load... so it omitted the where clause? This is the article I read which said to use objectSet's... since with POCO, I do not have EntityObject's to pass into "E" http://devtalk.dk/CommentView,guid,b5d9cad2-e155-423b-b66f-7ec287c5cb06.aspx

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  • LINQ entity query performance

    - by Abdel Olakara
    Hi all, I have a silly question. I would like to know if there is performance deference in these two quries: var cObject = from cust in entities.Customer where cust.id == cid select cust; and var cObject = entities.Customer.First( c=> c.id == cid); My query return only one record as I am querying with the primary key. But do they make any difference?

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  • Entity Framework 4 code-only reference column name

    - by Victor
    I created classes: public class Country { public long CountryId {get;set;} public string CountryName {get;set;} } public class Profile { public long ProfileId {get;set;} public string ProfileName {get;set;} public Country Country {get;set;} } and configuration for Profile: public class ProfileConfiguration : EntityConfiguration<Profile> { public IlluminatiCoreProfileConfiguration() { Relation(p => p.Country); } } Then I create context and run context.CreateDatabase(). New database contains table Profiles with column Country_CountryId. How can I write configuration for changing column name to "CountryId"? Thanks.

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  • Entity Framework - Many to Many Subquery

    - by Jorin
    I asked a question about this previously but my database structure has changed, and while it made other things simpler, now this part is more complicated. Here is the previous question. At the time, my EF Context had a UsersProjects object because there were other properties. Now that I've simplified that table, it is just the keys, so all my EF context knows about is Users and Projects and the M2M relationship between them. There is no more UsersProjects as far as EF knows. So my goal is to say "show me all the users who are working on projects with me." in SQL, this would go something like: SELECT * FROM Users INNER JOIN UsersProjects ON Users.ID=UsersProjects.UserID WHERE ProjectID IN (SELECT ProjectID FROM UsersProjects WHERE UserID=@UserID) and I started in EF with something like this: var myProjects = (from p in edmx.Projects where p.Users.Contains(edmx.Users.FirstOrDefault(u => u.Email == UserEmail)) orderby p.Name select p).ToList(); var associatedUsers = (from u in edmx.Users where myProjects.Contains(?????????) //where myProjects.Any(????????) select u); The trick is finding what to put in the ????????. Anyone help here?

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