Adding items to sub-array of an array doesn't work

Question

I have this class:

ActiveCampaign
{
     public Campaign campaign;
     public IEnumerable<CampaignView> Views;
}

ac is type of ActiveCampaign[]

The following code executes without any errors but nothing is added to its views. What amd I missing here?

ac.FirstOrDefault(a => a.Campaign.Id == c.Id).Views.ToList().Add(cv);

rory.ap · Accepted Answer · 2016-03-10 12:53:19Z

2

When you call ToList() you're creating a separate list; you're not adding to ac. You need to assign the return value:

List<ActiveCampaign> newList = ac.FirstOrDefault(a => a.Campaign.Id == c.Id).Views.ToList();

and then you can use it...

newList.Add(cv);

edited Mar 10, 2016 at 12:53

answered Mar 10, 2016 at 12:49

rory.ap

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1 Comment

Ashkan Mobayen Khiabani Over a year ago

I get an error Cannot implicitly convert type 'void' to 'System.Collections.Generic.List<ActiveCampaign>'

Jon Hanna · Accepted Answer · 2016-03-10 12:54:29Z

1

You're creating a new list that is a copy of the Views property, then adding to it, then throwing that list away.

If you want to permanently affect Views then make it a List or IList type and add to it directly.

If you want to see the views plus that new item then get the list into a variable before the add, or use Concat (or even better Append though it's currently only available in dotnet core) to create an enumeration of the views items along with the addition.

answered Mar 10, 2016 at 12:54

Jon Hanna

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