Entity Framework Insert Many to many creates duplicated data

Question

I have 3 Tables. Metadata, Rules, and a NxN relationship MetadataRules.

I'm inserting a Metadata, and my object contains a list of Rules that are retrieved from DB.

myMetadata.Rules = myListOfrules;

When i perform an insert, all the rules in myListOfRules are duplicated in the Rules table, instead of just creating a relationship. I'm inserting it with:

public static void InserirTipoMetadata( TA_TIPO_METADATA tipoMetadata ) {
    using ( EnterpriseContext context = new EnterpriseContext() ) {
        context.TipoMetadata.AddObject(tipoMetadata);
        context.SaveChanges(System.Data.Objects.SaveOptions.DetectChangesBeforeSave);
    }
}

What should i do to not duplicate the Rules?

Thanks!

Answer 1

I found a solution, but I don't think it is the right one...

public static void InserirTipoMetadata( TA_TIPO_METADATA tipoMetadata ) {
            using ( EnterpriseContext context = new EnterpriseContext() ) {
                List<TA_REGRA_VALID> regras = new List<TA_REGRA_VALID>();
                foreach ( var v in tipoMetadata.TA_REGRA_VALID ) {
                    regras.Add(context.Regra.Single(p => p.CO_SEQ_REGRA == v.CO_SEQ_REGRA));
                }
                tipoMetadata.TA_REGRA_VALID = regras;
                context.TipoMetadata.AddObject(tipoMetadata);
                context.SaveChanges(System.Data.Objects.SaveOptions.DetectChangesBeforeSave);
            }
        }

I'm selecting the rules again from the DB before trying to add. Is that the correct way?