CODEWITHSUNDEEP
c#
mattbloke
mattbloke

Reputation: 177

adding to icollection in viewmodel

I have an ICollection in my 'UserViewModel':

public ICollection<userpractice> userpractices { get; set; }

In my controller I am trying to add a userpractice to this collection in the viewmodel:

user user = db.users.Find(id);
UserViewModel uservm = new UserViewModel();

foreach (var up in user.userpractices)
{
    uservm.userpractices.Add(up);
}

I get an error saying 'Object reference not set to an instance of an object.' I dont know why because the up is definitely correctly assigned to a populated userpractice.

uservm.userpractices is null if that helps. But I think that should be null at first as the viewmodel doesnt have any userpractices in the collection!

Upvotes: 1

Views: 147

Answers (1)

Abbas
Abbas

Reputation: 14432

Yes, it is perfectly normal that uservm.userpractices is null at first. That's why you need to create a new instance of the collection before adding items to it. Example:

List<string> items;
items.Add("test"); //Object reference exception

First do this:

items = new List<string>();
items.Add("test"); //works

Upvotes: 4

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