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POEF 4.1 Fluent API. How to map two entities while using an existing join table which has three id columns?
 

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  1. POEF 4.1 Fluent API. How to map two entities while using an existing join table which has three id columns?
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    <p>I have three entities (EntityA, EntityB, EntityC) in code and their respective tables (TableA, TableB, TableC) in the database. I also have an existing join table that has three ID columns(TableA_ID, TableB_ID, TableC_ID).</p> <p>In code, the entities are related as follows:</p> <pre><code>MODELS: public class EntityA { public Guid EntityA_ID { get; set } ..... // Each EntityA can be associated with 0 or Many EntityB public virtual ICollection&lt;EntityB&gt; EntityBCollection { get; set; } } public class EntityB { public Guid EntityB_ID { get; set; } ..... // Each EntityB can be associated with 0 or Many EntityA public virtual ICollection&lt;EntityA&gt; EntityACollection { get; set; } // Each EntityB can be assocated with 0 or Many EntityC, // but it becomes 0 or 1 when EntityB is associated with an EntityA public virtual EntityC EntityC { get; set; } } public class EntityC { public Guid EntityC_ID { get; set; } ...... // Each EntityC an only be associated with a EntityB // an EntityC does not exist on its own public virtual EntityB EntityB { get; set; } } DATA CONTEXT: modelBuilder.Entity&lt;EntityB&gt;() .HasOptional(entityb =&gt; entityb.EntityC) .WithRequired(entityc =&gt; entityc.EntityB) .Map(map =&gt; { map.ToTable("ThreeIDColumnJoinTable").MapKey(new string[]{"EntityA_ID", "EntityB_ID", "EntityC_ID"}); }); </code></pre> <p>I keep on getting the following error:</p> <pre><code>Unable to determine the principal end of an association between the types 'EntityC' and 'EntityB'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations. </code></pre> <p>Any ideas on how I can reconfigure the mapping in the DATA CONTEXT so it will not produce an error and it will also include the relationship of EntityA that is specified in the ThreeIDColumnJoinTable?</p>
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    1. USSlauma
    1. USfuzzlog
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    1. CODon't you have an entity for the join table entries? Also I think you are misusing the `Map` method in the last line. This version is only to map foreign key column names (look at the description in Intellisense).
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      1. POEF 4.1 Fluent API. How to map two entities while using an existing join table which has three id columns?
      1. USSlauma
    2. COSlauma, did not create an entity for the join table since I've never had to previously (for straight forward many-to-may relationships with two columns). Also, the "map" code was my last attempt at all the different premutations I could think of. I'll try creating the join table entity to see what else comes up. thx.
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      1. POEF 4.1 Fluent API. How to map two entities while using an existing join table which has three id columns?
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    3. COYes, for many-to-many join tables you don't need an entity. But this table has to have precisely *two* columns which form a composite key and are FKs to the related tables. No other kind of join tables is allowed.
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      1. POEF 4.1 Fluent API. How to map two entities while using an existing join table which has three id columns?
      1. USSlauma
 

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