CODEWITHSUNDEEP
c#asp.net-mvcentity-framework
amhed
amhed

Reputation: 3659

Generic Repository Method throws conversion error

I have the following repository method that applies a filter and then orders the collection:

  public IQueryable<TE> SelectAll(Expression<Func<TE, bool>> predicate, 
            Expression<Func<TE, object>> sortExpression, bool orderDescending = false)
        {
            var list = _ctx.CreateQuery<TE>("[" + typeof(TE).Name + "]")
                .AsExpandable().Where(predicate);

            return orderDescending 
                ? list.OrderByDescending(sortExpression) 
                : list.OrderBy(sortExpression);
        }

The where predicate works fine, but when if the OrderBy is applied we get the following error:

Unable to cast the type 'System.Int32' to type 'System.Object'. LINQ to Entities only supports casting EDM primitive or enumeration types.

Edit: This is the calling code:

 var documentos = SelectAll(d => serviciosId.Contains(d.ServicioId) && d.TipoSociedadId == tipoSociedadId, d => d.Grupo);

Upvotes: 1

Views: 217

Answers (1)

educampver
educampver

Reputation: 3005

Try this:

public IQueryable<TE> SelectAll<TE, TKey>(Expression<Func<TE, bool>> predicate, 
            Expression<Func<TE, TKey>> sortExpression, bool orderDescending = false)
{
    var list = _ctx.CreateQuery<TE>("[" + typeof(TE).Name + "]")
                   .AsExpandable().Where(predicate);

    return orderDescending 
        ? list.OrderByDescending(sortExpression) 
        : list.OrderBy(sortExpression);
}

The problem is that the second parameter of the Func in the OrderBy clause is object in your code, and you are passing it an int, then it tries to cast that int to object. In the code I pasted above, you have an extra generic parameter that allows you to pass in any type for the ordering function, so, that should work.

Upvotes: 1

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