Entity Framework ignore not included foreign keys-CodePudding

In my .net 6.0 project I use the Entity Framework 6 to get data from my database.

My model contains a foreign key, which is used to resolve the data of the id.

I use the following call to resolve the foreign key:

// ...
_context.Tools.Include(t => t.User).ToListAsync();
// ...

My Tool Model looks like this:

[Table("MY_TOOLS")]
public class Tool
{
    [Key]
    [Column("ID")]
    public int Id { get; set; }
    
    [Column("UPDATED_BY")]
    public int? UpdatedBy { get; set; }

    [ForeignKey("UpdatedBy")]
    public User? User { get; set; }
}

My User class looks like this:

[Table("MY_USERS")]
public class User
{
    [Key]
    [Column("ID")]
    public int Id { get; set; }
    [Column("EMAIL")]
    public string? Email { get; set; }
}

When I leave the include like described above, the user is resolved correctly.

Is there a way to remove the user property from the loaded data, when I don't explicitly tell the Model to resolve the foreign key?

CodePudding user response：

It shouldnt resolve it by default as it uses lazy loading. You would have to query it specifically for the user object to get it e.g. _context.My_Tools.include(uvar = uvar.User).FirstOrDefault();

So you just make a method called getToolEager() and one called getTool() it would be a "waste" of a call to query for the user object only to throw it away in case you might not need it.

CodePudding user response：

You have 2 options:

Lazy Loading Proxy

Use Lazy Loading as described here: https://learn.microsoft.com/en-us/ef/core/querying/related-data/lazy

After just load data as _context.Tools.ToListAsync(); and users will load when you try access them.

Manually load related data

Modify Tool to explicitly store User FK:

[Table("MY_TOOLS")]
public class Tool
{
    [Key]
    [Column("ID")]
    public int Id { get; set; }
    
    [Column("UPDATED_BY")]
    public int? UpdatedBy { get; set; }

    [ForeignKey("UpdatedBy")]
    public User? User { get; set; }
 
    public int? UpdatedBy{ get; set; }
}

So when you load data as _context.Tools.ToListAsync(); fieldUser will be null but UpdatedBy will have User Id(if FK is not null in DB), so you can manually load them manually like tool.User = await _context.Users.FirstOrDefaultAsync(t => t.Id == tool.UpdatedBy);