query a class object using linq

I am trying to query a class object.

My class :

public class Result
{
   public List<Driver>  Drivers { get; set; }
   public List<Vehicle> Vehicles { get; set; }       
}

I have method to which I am passing an object of this class

  public string BuildRequestXML(Result  开发者_JAVA百科input)
     { 
       var driverNames = new List<Name>(); 
       input.Drivers.ForEach(cd => driverNames.Add(cd.Name)); 
     }                                                                                         

I get Object reference not set to instance error @ the 2nd line of code in the above function.

Thanks in advance. BB.

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You'll have to debug to find which one it is, but that exception could be because either input or input.Drivers is null. You could even have a null Driver in the Drivers list.

As for your driversName list, you could rewrite that as

var driverNames = input.Drivers.Select(driver => driver.Name).ToList();

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I am not exactly sure why you are getting this problem, however, a better approach would be to use a Select 'projection' as follows:

driverNames  = input.Drivers.Select(d => d.Name).ToList();