CODEWITHSUNDEEP
c#asp.net-mvc-3list
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Reputation: 5105

C# Add Object To List

I have created a new empty List of type User (User is an Entity in my EDM)

List<User> AvailableLocums = new List<User>();
AvailableLocums = null;

I also have another List of type User which is populated with the results of a query

List<User> Locums = _shiftDateService.GetAvailableLocums(id, shiftDate.shiftDateID).ToList();

I then wish to loop around the Locums List, do some logic, and then add the User to my AvailableLocums List

foreach (var locum in Locums)
{
   //Do some logic

   AvailableLocums.Add(locum);

}

However, when I try to do this I get the following error

Object reference not set to an instance of an object.

I then tried to amend my code and do the following

foreach (var locum in Locums)
{
       //Do some logic

       User locumUser = new User();
       locumUser = locum;

       AvailableLocums.Add(locumUser);     
}

But again I get the same error

Object reference not set to an instance of an object.

Could someone please help me with this?

Thanks.

Upvotes: 0

Views: 3968

Answers (5)

Vijay Sawariya
Vijay Sawariya

Reputation: 1

Try this code.

List<User> AvailableLocums = null; 
List<User> Locums = _shiftDateService.GetAvailableLocums(id, shiftDate.shiftDateID).ToList();  
AvailableLocums = Locums.Where(newUserRecord => newUserRecord != null).ToList();

* you can take any name instead of "newUserRecord".

Upvotes: 0

Fredrik
Fredrik

Reputation: 2317

You are telling your variable "AvailableLocums" to no longer point to anything in memory.

Remove: AvailableLocums = null;

how about:

List<User> AvailableLocums;
List<User> Locums;

// get id for shift date service
// int id = ...

// get locums from shift date service 
Locums = _shiftDateService.GetAvailableLocums(id, shiftDate.shiftDateID).ToList();

// time to add to AvailableLocums
if(AvailableLocums == null)
    AvailableLocums = new List<User>();

foreach (var locum in Locums)
{
   //Do some logic

   AvailableLocums.Add(locum);
}

Upvotes: 5

maxs87
maxs87

Reputation: 2284

try to 

List<User> Locums = new List<User>();

before _shiftDateService.GetAvailableLocums...

Upvotes: 0

Davecz
Davecz

Reputation: 1221

get out this line :

AvailableLocums = null;

and it will be Ok ... You declaring new object and on next row set it to null?

Upvotes: 1

Daniel A. White
Daniel A. White

Reputation: 191058

You are nulling out that list

List<User> AvailableLocums = new List<User>();
AvailableLocums = null; // HERE

hence, the exception. You don't need this line to make an empty list:

AvailableLocums = null;

Upvotes: 3

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