Wrong navigation properties when using SQLite and Entity Framework 6 - sqlite

Question

Lately I've been playing around with SQLite using Entity Framework but something is not very clear to me regarding the navigation properties of the generated entities after DB first approach. And more specifically, many-to-many relationships.
Note: Using ASP.NET Web Api OWIN project.
This is what I did:
I installed latest version of Entity Framework
I installed latest version of System.Data.SQLite
I used Firefox add-on to create my database. It generated my *.sqlite
Example for one of my many-to-many db definitions while creating the DB:
CREATE TABLE "Users"
(
"Id" INTEGER PRIMARY KEY NOT NULL UNIQUE ,
"IdSrvId" INTEGER NOT NULL UNIQUE ,
"FirstName" VARCHAR NOT NULL ,
"LastName" VARCHAR NOT NULL ,
"Email" VARCHAR NOT NULL ,
"About" VARCHAR NOT NULL ,
"GenderId" INTEGER NOT NULL UNIQUE ,
"BirthDate" DATETIME,
"PhoneNumber" VARCHAR
)
CREATE TABLE "UserLanguаges"
(
"Id" INTEGER PRIMARY KEY NOT NULL UNIQUE ,
"UserId" INTEGER NULL REFERENCES Users(Id),
"LanguageId" INTEGER NULL REFERENCES Languаges(Id)
)
CREATE TABLE "Langugaes"
(
"Id" INTEGER PRIMARY KEY NOT NULL UNIQUE ,
"Name" VARCHAR NOT NULL UNIQUE
)
After that, I used Visual Studio 2015 to create a Data Model using that *.sqlite file. Following this tutorial: SQLite EntityFramework 6 Tutorial
After the generation I got all of my tables as entities looking like this:
public partial class User
{
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
public User()
{
this.GroupUsers = new HashSet<GroupUser>();
this.UserLanguаges = new HashSet<UserLanguаges>();
}
public long Id { get; set; }
public long IdSrvId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Email { get; set; }
public string About { get; set; }
public long GenderId { get; set; }
public Nullable<System.DateTime> BirthDate { get; set; }
public string PhoneNumber { get; set; }
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
public virtual ICollection<UserLanguаges> UserLanguаges { get; set; }
}
public partial class Languаges
{
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
public Languаges()
{
this.UserLanguаges = new HashSet<UserLanguаges>();
}
public long Id { get; set; }
public string Name { get; set; }
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
public virtual ICollection<UserLanguаges> UserLanguаges { get; set; }
}
public partial class UserLanguаges
{
public long Id { get; set; }
public Nullable<long> UserId { get; set; }
public Nullable<long> LanguageId { get; set; }
public virtual Languаges Languаges { get; set; }
public virtual User User { get; set; }
}
What worries me here, are the navigation properties inside User and Language entities. As you can see, they make a reference to the 'bridge' table helping for the many-to-many relationship but not directly to the other entity as I expected.
I expected this:
public virtual ICollection<UserLanguаges> UserLanguаges { get; set; }
to look like this:
public virtual ICollection<Languаge> Languаges { get; set; }
inside of the User entity.
How can I fix that?

Answer 1

The only time Entity Framework can omit the join table is if that table consists purely of the keys of the tables being joined in a many-to-many relationship. It's the presence of the Id column on this table that is causing it to generate a new entity.
The only way around this is to remove that Id column and make that table have a composite key consisting of the UserId and LanguageId keys. If you cannot change the database schema, there's no other option but take a deep breath and accept how it works.
Some additional reading on how EF handles many-to-many relationships: https://msdn.microsoft.com/en-us/library/dd742359.aspx