Question

Many thanks to leppie:
Currently I got

Expression<Func<vwMailMerge,bool>> whereClause= null;
List<vwMailMerge> mailMergeItems = null;

int personType = mailMergeSettings.PersonType.ToInteger();
if (personType > 0)
{
    whereClause = this.MailMergeWhereClause(whereClause, f => f.MemberTypeId == personType);
}
if (mailMergeSettings.PersonIds != null)
{
    var personIds = mailMergeSettings.PersonIds.ToGuidArray();
    if (personIds != null && personIds.Length > 0)
    {
        var personList = personIds.ToList();
        whereClause = this.MailMergeWhereClause(whereClause, f => personList.Contains(f.UserId));
    }
}

mailMergeItems = this.ObjectContext.vwMailMerges.Where(whereClause).ToList();
private Expression<Func<vwMailMerge, bool>> MailMergeWhereClause(params Expression<Func<vwMailMerge, bool>>[] wheres)
{
    if (wheres.Length == 0)
    {
        return x => true;
    }
    Expression result;   
    if (wheres[0] == null)
    {
        result = wheres[1].Body;
        return Expression.Lambda<Func<vwMailMerge, bool>>(result, wheres[1].Parameters);
    }
    else
    {
        result = wheres[0].Body;
        for (int i = 1; i < wheres.Length; i++)
        {
            result = Expression.And(result, wheres[i].Body);
        }
        return Expression.Lambda<Func<vwMailMerge, bool>>(result, wheres[0].Parameters);
        }     
    }
}

When it gets to “mailMergeItems =” it drops and gives error: “The parameter ‘f’ was not bound in the specified LINQ to Entities query expression.”

I’ve noticed that when checking only for people, or only for membertypeId, it works properly.. but combined the 2nd gives a error on it’s “f=>” I think.

Answer 1

You could reformat your question better with the code tool.

However it looks like you could approach the problem in this way to avoid all those func expressions floating around:

this.ObjectContext.vwMailMerges.Where(mm=>IsValidMailMerge(mm,personType)).ToList()


private bool IsValidMailMerge(YourType mailmerge, YourType2 personType)
{
if(...) // type specific criteria here
return true;
else
return false;
}