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POHow can I send where statements to a method which are dynamically executed in a LINQ statement?
 

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  1. POHow can I send where statements to a method which are dynamically executed in a LINQ statement?
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    <p>In the following example, <strong>GetFilteredCustomers()</strong> works fine so I can send various letters which I want customers to have in their last name.</p> <p><strong>But how can I build GetFilteredCustomersDynamic() which will enable me to send a full where clause that can be dynamically included in the LINQ statement?</strong></p> <pre><code>using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace TestDynamicLinq2343 { public class Program { static void Main(string[] args) { List&lt;Customer&gt; customers = Customer.GetCustomers(); //semi-dynamic foreach (var customer in Customer.GetFilteredCustomers(customers, "o")) { Console.WriteLine(customer.LastName); } //fully-dyanmic (can send where clauses) foreach (var customer in Customer.GetFilteredCustomersDynamic(customers, c =&gt; c.FirstName.Contains("a"))) { Console.WriteLine(customer.LastName); } Console.ReadLine(); } } public class Customer { public string FirstName { get; set; } public string LastName { get; set; } public string Street { get; set; } public string Location { get; set; } public string ZipCode { get; set; } public static List&lt;Customer&gt; GetCustomers() { List&lt;Customer&gt; customers = new List&lt;Customer&gt;(); customers.Add(new Customer { FirstName = "Jim", LastName = "Jones" }); customers.Add(new Customer { FirstName = "Joe", LastName = "Adams" }); customers.Add(new Customer { FirstName = "Jake", LastName = "Johnson" }); return customers; } public static List&lt;Customer&gt; GetFilteredCustomers(List&lt;Customer&gt; customers, string letter) { return (from c in customers where c.LastName.Contains(letter) select c).ToList(); } public static List&lt;Customer&gt; GetFilteredCustomersDynamic(List&lt;Customer&gt; customers, Func&lt;..., bool&gt; whereClause) { return (from c in customers where ...whereClause... select c).ToList(); } } } </code></pre> <h1>Answer:</h1> <p>thanks elder_george and arjuns, I got this example to work like this (albeit without the <code>Expression&lt;&gt;</code> ):</p> <pre><code>using System; using System.Collections.Generic; using System.Linq; namespace TestDynamicLinq2343 { public class Program { static void Main(string[] args) { List&lt;Customer&gt; customers = Customer.GetCustomers(); Func&lt;Customer, bool&gt; whereClause = c =&gt; c.LastName.Contains("a") &amp;&amp; c.FirstName.Contains("J"); foreach (var customer in Customer.GetFilteredCustomers(customers, whereClause)) { Console.WriteLine(customer.LastName); } Console.ReadLine(); } } public class Customer { public string FirstName { get; set; } public string LastName { get; set; } public string Street { get; set; } public string Location { get; set; } public string ZipCode { get; set; } public static List&lt;Customer&gt; GetCustomers() { List&lt;Customer&gt; customers = new List&lt;Customer&gt;(); customers.Add(new Customer { FirstName = "Jim", LastName = "Jones" }); customers.Add(new Customer { FirstName = "Joe", LastName = "Adams" }); customers.Add(new Customer { FirstName = "Jake", LastName = "Johnson" }); customers.Add(new Customer { FirstName = "Angie", LastName = "Reckar" }); customers.Add(new Customer { FirstName = "Jean-Luc", LastName = "Beaudoir" }); return customers; } public static List&lt;Customer&gt; GetFilteredCustomers(List&lt;Customer&gt; customers, Func&lt;Customer, bool&gt; whereClause) { return customers .Where(whereClause).ToList(); } } } </code></pre>
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