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POEF Code First Many-to-Many not working
 

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  1. POEF Code First Many-to-Many not working
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    <p>Using the Entity Framework Code First paradigm I have defined the following objects and relationships as part of an ASP.Net MVC3 application. The problem is the many-to-many relationship between the Photo and Gallery objects is not working properly.</p> <p>Currently a gallery can contain many photos - this is correct. But a photo can only be associated with one Gallery - this is incorrect. I want a photo to be able to be in many galleries. If I add a photo to a gallery when it is already associated with another gallery, it is removed from the other gallery.</p> <p>I would very much appreciate your solutions on how to make this many-to-many relationship work.</p> <p>Here's my code:</p> <pre><code>public class Photo { public int ID { get; set; } public string Title { get; set; } public virtual ICollection&lt;Gallery&gt; Galleries { get; set; } } public class Gallery { public int ID { get; set; } public string Title { get; set; } public virtual ICollection&lt;Photo&gt; Photos { get; set; } } protected override void OnModelCreating(DbModelBuilder modelBuilder) { /* I would expect the following to cause a lookup table to * be created but it isnt */ modelBuilder.Entity&lt;Photo&gt;().HasMany&lt;Gallery&gt;(p =&gt; p.Galleries); modelBuilder.Entity&lt;Gallery&gt;().HasMany&lt;Photo&gt;(g =&gt; g.Photos); } </code></pre> <p>I am using the following code within my own custom database initializer.</p> <pre><code>public void InitializeDatabase(PhotoDBContext context) { var dbCreationScript = ((IObjectContextAdapter)context).ObjectContext.CreateDatabaseScript(); Log(dbCreationScript); context.Database.ExecuteSqlCommand(dbCreationScript); } </code></pre> <p>By logging the dbCreationScript variable I can see that the relevant sql that is generated for these tables is as follows.</p> <pre><code>create table [dbo].[Galleries] ( [ID] [int] not null identity, [Title] [nvarchar](max) null, [Photo_ID] [int] null, primary key ([ID]) ); create table [dbo].[Photos] ( [ID] [int] not null identity, [Title] [nvarchar](max) null, [Gallery_ID] [int] null, primary key ([ID]) ); alter table [dbo].[Photos] add constraint [Gallery_Photos] foreign key ([Gallery_ID]) references [dbo].[Galleries]([ID]); alter table [dbo].[Galleries] add constraint [Photo_Galleries] foreign key ([Photo_ID]) references [dbo].[Photos]([ID]); </code></pre> <p>As you can see there is no SQL generated to create a lookup table which is probably why the relationship is not working - why isnt a lookup table being created?</p>
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    1. COThe ID member should be named Class + ID e.g. PhotoId and GalleryId. This may help. As you can see in the db scripts it has added a pk for the tables.
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