Search code examples
entity-frameworkmetadataodatawcf-data-services

OData $metadata error

I have a WCF Data Service (5.5) sitting over an EF (5.0) model, I'm getting the following error when I query $metadata:

"An IEdmModel instance was found that failed validation. The following errors were reported: InvalidMultiplicityOfDependentEnd : The multiplicity of the dependent end 'QuestionsetMember' is not valid. Because the dependent properties don't represent the dependent end key, the the multiplicity of the dependent end must be '*'."

QuestionsetMember has a composite primary key of 2 columns, each of which is hooked to a primary key of another table, i.e. a foreign key exist from each column of the key to the two tables' primary keys.

I've searched but cannot find any info on "InvalidMultiplicityOfDependentEnd". Also tried fiddling with the relationships in the EDMX, but changing the End Multiplicity causes errors which won't allow the model to compile.

Any ideas how to get round this (hopefully without changing my schema) ?

Solution

  • This seems to be a very rare error. I did not find anywhere else an explanation of that error. So i did find for me a solution after inspecting every single constraint and every column in both tables. To my great surprise the order of the primary key columns seems to be relevant.

    For explanation: I do the database-design within the sql server management studion, and update my model with the entity framework designer.

    First Table:

    CREATE TABLE Table1
(
Column1 int NOT NULL,
Column2 int NOT NULL,
PRIMARY KEY (Column1,Column2)
)

    Second Table:

    CREATE TABLE Table2
(
Column1 int NOT NULL,
Column2 int NOT NULL,
PRIMARY KEY (Column1,Column2)
FOREIGN KEY (Column1,Column2) REFERENCES Table1(Column1,Column2)
)

    This would work. But it do not work, if you would define the columns of the primary key in the second table in another order:

    CREATE TABLE Table2
(
-- Changed order in definition:
Column1 int NOT NULL,
Column2 int NOT NULL,
-- Changed order in PK group:
PRIMARY KEY (Column2,Column1)
-- Leave the FK definition untouched:
FOREIGN KEY (Column1,Column2) REFERENCES Table1(Column1,Column2)
)

    I think the order of the column definition has impact on the generated model. And this order could maybe have an impact in the model validation within the IEdmModel class. Who knows...