Stored procedure and identity column

I have write a stored procedure for aggregate values to test, a very simple query:

 CREATE PROCEDURE proc_pesee_groupby AS 
   SELECT 
    PESEE.NUM_TRAITEMENT,
    PESEE.NUM_BLOC,
    SUM(PESEE.POIDS_NET) AS POIDS
FROM
    PESEE
WHERE
    PESEE.ID_ESSAI = 470
GROUP BY
    PESEE.NUM_TRAITEMENT,
    PESEE.NUM_BLOC

But when I execute this line in my project:

IList<ProcPeseeGroupbyResult> regroupement = unitOfWork.ProcPeseeGroupby();

I have an 'Mindscape.LightSpeed.LightSpeedException error :

    No Id returned from stored procedure 'proc_pesee_groupby'.  
   Check that the stored procedure selects the identity column

Why it's necessary to have an identity column in a stored procedure ? I do not understand. Is somebody can help me ? I am very disapointed.

If you are loading entities via a stored procedure they need to have an Id which is why the error is raised - those generated methods using UnitOfWork.Find(ProcedureQuery) which is intended to load entities. Given you dont want to return an Id though you can use UnitOfWork.Project(ProcedureQuery) as this does not require an Id to be present.

Have a look at the generated code for ProcPeseeGroupby() and then use a manual call to UnitOfWork.Project leveraging the same procedure query you see in the generated method.

Jeremy

Thank's for the reply. I bypassed the problem by adding a temporary identifier :

SELECT 
    ROW_NUMBER() OVER(ORDER BY PESEE.NUM_TRAITEMENT,PESEE.NUM_BLOC, PESEE.ID_LISTEQUALITE) AS PROCID,
    PESEE.NUM_TRAITEMENT,
    PESEE.NUM_BLOC,
    PESEE.ID_LISTEQUALITE,
    SUM(PESEE.POIDS_NET) AS POIDS
FROM
    PESEE
WHERE
    PESEE.ID_ESSAI = @ESSAI_ID
GROUP BY
    PESEE.NUM_TRAITEMENT,
    PESEE.NUM_BLOC,
    PESEE.ID_LISTEQUALITE