using .Equals() failing in Predicatebuilder

Question

Hi I am using Predicate builder to build up my where clause. I noticed that it was doing a case sensitive comparison against the entity datasource. Some quick googling implies this is a feature of linqtoentities. so i have had to modify my code to do

whereClause = whereClause.And(x => x.county.Equals(oSearch.County, StringComparison.OrdinalIgnoreCase ));

rather than previously doing

whereClause = whereClause.And(x => x.county == oSearch.County);

The problem is now it appears to be failing building a whereclause.

incidentally i am using the code below which was working before.

var tbl = db.tbl_members.AsExpandable().Where(whereClause.Compile());

I have code which does a foreach (var item in Model) this is now failing with a "Object reference not set to an instance of an object" if i examine the model using quick view it now shows this

tblMembers = {System.Linq.Enumerable.WhereEnumerableIterator<tbl_members>}

rather than

  tblMembers = {SELECT [Extent1].[id] AS [id], 
[Extent1].[membership_id] AS [membership_id], 
[Extent1].[membership_type] AS [membership_type], 
[Extent1].[institution] AS [institution], 
[Extent1].[full_name] AS [full_name], 
[Extent1].[address1] AS [address1], 
...

which it showed previously regardless of any results or not.

Answer 1

Given this:

tblMembers = {System.Linq.Enumerable.WhereEnumerableIterator<tbl_members>}

it looks like you're inadvertently using LINQ to Objects. Check whether your copy of PredicateBuilder is actually in terms of expression trees (Expression<Func<T, bool>>) or delegates (Func<T, bool>) - you should be using expression trees.

EDIT: As noted in comments, this is the problem:

var tbl = db.tbl_members.AsExpandable().Where(whereClause.Compile());

That's compiling the expression tree into a delegate, and then calling Enumerable.Where. Without the Compile() call:

var tbl = db.tbl_members.AsExpandable().Where(whereClause);

... we end up calling Queryable.Where using the expression tree, which can then be converted into SQL.

Answer 2

The problem is that linq has translation for

whereClause = whereClause.And(x =>
x.county.Equals(oSearch.County,StringComparison.OrdinalIgnoreCase )

in the sql. You can try:

whereClause = whereClause.And(x => x.county.ToLower()==oSearch.County.ToLower());