CODEWITHSUNDEEP
linq
Bill McKnight
Bill McKnight

Reputation: 101

Make Linq.Expression suitable for where predicate?

The new WCF Data Services toolkit allows you to obtain a parameter, which contains a property called FilterExpression of type System.Linq.Expressions.Expression. This property contains all the filters provided in the query-string parsed as an expression tree. This can be useful to improve performance by carrying out the filter server side.

However, you cannot just pass the filter expression to a where clause. Assuming the filter expression is an Expression type, is there an easy way to make use of it in a server side linq to sql query?

This doesn't work: var query.Where(filterexpression).ToList();

Upvotes: 0

Views: 203

Answers (2)

Meligy
Meligy

Reputation: 36594

What you need is anything that can be Expression< Func<TEntityType, bool> > for any Queryable of type IQueryab<TEntityType>.

Upvotes: 1

Jacob
Jacob

Reputation: 78848

Actually, if query is of type IQueryable<T>, you can pass in an Expression. If you're using Linq to SQL, you should have access to IQueryable<T> objects.

Upvotes: 0

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