Error in LINQ (column doesn't exist) when using Entity Framework

Question

This question is generalization of my previous question:

Error in LINQ when work with PostGreSQL by Entity Framework
I have hypothesis, that, If between 2 tables exist more than 1 relation (7 for my example), EF try to normalize this table by adding additional column.

For example model a:

public partial class a
{        
    [Key]
    public int id { get; set; }

    [ForeignKey("contractors"), Column(Order = 0)]
    public Nullable<int> ot_contractor_id { get; set; }

    [ForeignKey("contractors1"), Column(Order = 1)]
    public Nullable<int> gvo_contractor_id { get; set; }

    public virtual contractors contractors { get; set; }
    public virtual contractors contractors1 { get; set; }    
}

Table [a] have relations to table [contractors].[id] So, EF generate column's "contractors_id" and "contractors1_id".

Other tables have only 1 relation and they work normal!

The question: Is that hypothesis correct?! And the problem of excess column comes from unnormal tables with a few relations? Thanks!

Slauma · Accepted Answer · 2013-07-19 16:26:11Z

2

It can happen if you have inverse navigation properties in contractors class, like so:

public partial class contractors
{
    //...

    public virtual ICollection<a> aCollection { get; set; }
    public virtual ICollection<a> aCollection1 { get; set; }
}

In this case EF won't know which one belongs to which navigation property in class a and assume four relationships instead of two (or three instead of two if you have only one collection). Those additional relationships will have a separate foreign key and one of them is contractors_id. If that doesn't exist in the database you get an exception.

You can fix the problem by applying the InverseProperty attribute in class a:

[InverseProperty("aCollection")]
public virtual contractors contractors { get; set; }
[InverseProperty("aCollection1")]
public virtual contractors contractors1 { get; set; }

answered Jul 19, 2013 at 16:26

Slauma

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1 Comment

Oleg Over a year ago

Thank's for your answer! I will try it tomorrow! I'll report about results.

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