Multiple Dynamic Conditions With Or Operator

Question

I use Entity Framework 5 and i've a dynamic linq query. But i need i have to connect two conditions with "OR" operator. For example i can use this in normal sql text as this.

SELECT * FROM Products WHERE 
(Keywords LIKE '%keyw1%' AND Keywords LIKE '%keyw2%') OR (ProdName LIKE '%ProdName%')

My linq query below. But i need create where conditions dynamically. How can i do this?

var prodQuery = from p in _db.Products
    select p;

searchText.Split(' ')
    .ForEach(
        s =>
            prodQuery =
                prodQuery.Where(
                    p => p.Product.Keywords.Contains(s)));

//i need here "OR" operator. I have to connect this line with "OR" to upper condition
prodQuery = prodQuery.Where(p => p.ProdName.Contains("test prod"))

and in general, search for `PredicateBuilder` and `Or` – xanatos Jun 20 '15 at 17:19 — xanatos, Jun 20 '15 at 17:19

Brad C · Answer 1 · 2015-06-20T17:18:24.527

Have you tried something like:

searchText.Split(' ')
    .ForEach(s => prodQuery = prodQuery
        .Where(p => p.Product.Keywords.Contains(s)) || p.ProdName.Contains("test prod")
    );

Heres a cleaner version of it that should work for you:

string[] searchTerms = searchText.Split(' ');
var prodQuery = _db.Products.Any(p => 
    p.Product.Keywords.Any(k => searchTerms.Contains(k)) 
    || searchTerms.Contains(p.ProdName)
);

score 0 · Answer 2 · answered Jun 22 '15 at 01:20

What you should do is to build your query condition in an expression tree and then apply it to your linq object.

You can use this PredicateBuilder class to do so.

public static class PredicateBuilder
{
    public static Expression<Func<T, bool>> True<T>() { return f => true; }
    public static Expression<Func<T, bool>> False<T>() { return f => false; }

    public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expr1, Expression<Func<T, bool>> expr2)
    {
        var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
        return Expression.Lambda<Func<T, bool>>
          (Expression.OrElse(expr1.Body, invokedExpr), expr1.Parameters);
    }

    public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> expr1, Expression<Func<T, bool>> expr2)
    {
        var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
        return Expression.Lambda<Func<T, bool>> (Expression.AndAlso(expr1.Body, invokedExpr), expr1.Parameters);
    }
}

And Now Your Code:

var prodQuery = from p in _db.Products
   select p;

var condition = PredicateBuilder.False<Product>();

searchText.Split(' ')
    .ForEach(s => condition = condition.And(p => p.Product.Keywords.Contains(s)));

condition = condition.Or(p => p.ProdName.Contains("test prod"));
prodQuery = prodQuery.Where(condition);

Multiple Dynamic Conditions With Or Operator

2 Answers2