Entity Framework null pointer reference exception

Question

I have a relationship between two tables

First table: User

Id | Name |

Second table: Package

Id | UserSenderId | UserReceiverId

I use Entity Framework with .Net Framework 3.5 and the problem I have is that Entity Framework is creating two references UserReference1 and UserReference but UserReference1 is always null. If I do not include the User table like this:

db.Packages.Include("User")

then UserReference is also null.

I really run out of ideas with this problem, is there an issue using multiple foreign keys pointing to the same primary key?

EDIT 1:

The user reference in Package partial class:

[global::System.Data.Objects.DataClasses.EdmRelationshipNavigationPropertyAttribute("Tema4Model", "FK_Package_User_Receiver", "User")]
[global::System.CodeDom.Compiler.GeneratedCode("System.Data.Entity.Design.EntityClassGenerator", "4.0.0.0")]
[global::System.Xml.Serialization.XmlIgnoreAttribute()]
[global::System.Xml.Serialization.SoapIgnoreAttribute()]
[global::System.Runtime.Serialization.DataMemberAttribute()]
public User User
{
    get
    {
        return ((global::System.Data.Objects.DataClasses.IEntityWithRelationships)(this)).RelationshipManager.GetRelatedReference<User>("Tema4Model.FK_Package_User_Receiver", "User").Value;
    }
    set
    {
        ((global::System.Data.Objects.DataClasses.IEntityWithRelationships)(this)).RelationshipManager.GetRelatedReference<User>("Tema4Model.FK_Package_User_Receiver", "User").Value = value;
    }
}

/// <summary>
/// There are no comments for User in the schema.
/// </summary>
[global::System.ComponentModel.BrowsableAttribute(false)]
[global::System.CodeDom.Compiler.GeneratedCode("System.Data.Entity.Design.EntityClassGenerator", "4.0.0.0")]
[global::System.Runtime.Serialization.DataMemberAttribute()]
public global::System.Data.Objects.DataClasses.EntityReference<User> UserReference
{
    get
    {
        return ((global::System.Data.Objects.DataClasses.IEntityWithRelationships)(this)).RelationshipManager.GetRelatedReference<User>("Tema4Model.FK_Package_User_Receiver", "User");
    }
    set
    {
        if ((value != null))
        {
            ((global::System.Data.Objects.DataClasses.IEntityWithRelationships)(this)).RelationshipManager.InitializeRelatedReference<User>("Tema4Model.FK_Package_User_Receiver", "User", value);
        }
    }
}

/// <summary>
/// There are no comments for User1 in the schema.
/// </summary>
[global::System.Data.Objects.DataClasses.EdmRelationshipNavigationPropertyAttribute("Tema4Model", "FK_Package_User_Sender", "User")]
[global::System.CodeDom.Compiler.GeneratedCode("System.Data.Entity.Design.EntityClassGenerator", "4.0.0.0")]
[global::System.Xml.Serialization.XmlIgnoreAttribute()]
[global::System.Xml.Serialization.SoapIgnoreAttribute()]
[global::System.Runtime.Serialization.DataMemberAttribute()]
public User User1
{
    get
    {
        return ((global::System.Data.Objects.DataClasses.IEntityWithRelationships)(this)).RelationshipManager.GetRelatedReference<User>("Tema4Model.FK_Package_User_Sender", "User").Value;
    }
    set
    {
        ((global::System.Data.Objects.DataClasses.IEntityWithRelationships)(this)).RelationshipManager.GetRelatedReference<User>("Tema4Model.FK_Package_User_Sender", "User").Value = value;
    }
}

/// <summary>
/// There are no comments for User1 in the schema.
/// </summary>
[global::System.ComponentModel.BrowsableAttribute(false)]
[global::System.CodeDom.Compiler.GeneratedCode("System.Data.Entity.Design.EntityClassGenerator", "4.0.0.0")]
[global::System.Runtime.Serialization.DataMemberAttribute()]
public global::System.Data.Objects.DataClasses.EntityReference<User> User1Reference
{
    get
    {
        return ((global::System.Data.Objects.DataClasses.IEntityWithRelationships)(this)).RelationshipManager.GetRelatedReference<User>("Tema4Model.FK_Package_User_Sender", "User");
    }
    set
    {
        if ((value != null))
        {
            ((global::System.Data.Objects.DataClasses.IEntityWithRelationships)(this)).RelationshipManager.InitializeRelatedReference<User>("Tema4Model.FK_Package_User_Sender", "User", value);
        }
    }
}

Any help is appreciated, thanks!

Possible duplicate of [What is a NullReferenceException, and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — jdphenix, Dec 24 '16 at 20:35
Please show C# code for `Package` and `User` entities that was generated by Entity Framework or written by yourself in case of code-first approach. — Oleksandr Kobylianskyi, Dec 24 '16 at 20:39
@jdphenix I have read the answers to that question but that is not the problem that I have, my problem is that Entity Framework id creating a reference for only one foreign key from the two mentioned above — sixfeet, Dec 24 '16 at 20:40
@OleksandrKobylianskyi It'a a lot of generated code, in my question I have tried to simplify the problem — sixfeet, Dec 24 '16 at 20:42
ok, then please check that `Package` class indeed contains `User` property — Oleksandr Kobylianskyi, Dec 24 '16 at 20:45
It's very odd how the classes are generated in .Net 3.5, I have worked with Entity Framework in .Net 4.5 but is nothing like that — sixfeet, Dec 24 '16 at 20:48
If do not include user like in the question both are null. If I include User then only User1 is null — sixfeet, Dec 24 '16 at 21:06

Oleksandr Kobylianskyi · Accepted Answer · 2016-12-24T21:08:06.543

1

Try db.Packages.Include("User").Include("User1")

edited Dec 24 '16 at 21:08

answered Dec 24 '16 at 20:55

Oleksandr Kobylianskyi

3,281
20
33

It's working but I do not understand why, can you explain, please? – sixfeet Dec 24 '16 at 21:29
I guess you assume that `Include` loads all navigations properties with type `User`. But `Include` string parameter means concrete property not all properties of the type. You should call `Include` for each navigation property that you are going to include. – Oleksandr Kobylianskyi Dec 24 '16 at 21:35

Entity Framework null pointer reference exception

1 Answers1