How to create predicate dynamically

Question

Hi i want to create a list based on the search string using predicate expressions.

I have a list of type products contains different names.

List


        

Answer 1

Initialize the predicate as false

Expression> predicate = PredicateBuilder.False();

You need to combine the predicates using Or

foreach (string str in SearchItems)
{
    string temp = str;
    predicate = predicate.Or(p => p.NameToLower().Contains(temp.ToLower()));                   
}

Source for predicate builder here. It is part of LINQKit

Code, in case link goes

using System;
using System.Linq;
using System.Linq.Expressions;
using System.Collections.Generic;

public static class PredicateBuilder
{
  public static Expression> True ()  { return f => true;  }
  public static Expression> False () { return f => false; }

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

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