Using IEnumerable<T> to add instances of an object in .net core

Question

I need to add an object to an IEnumerable but not 100% sure how to do it. It appears .add isn't working for me in my .net core 3.1 code.

The first class is this:

 public class ContainerA
{
    public string TestA { get; set; }

    public IEnumerable<ContainerB> Containers { get; set; }
}

Then there is the ContainerB class:

public class ContainerB
{
    public string TextString { get; set; }
}

I am unsure about how to add a bunch of Continers of object ContainerB to the instance object of ContainerA, like so:

var contA = new ContainerA();

contA.TestA = "works fine";

// Issues here and how to get lots of ContainerB.TestString into the contA instance.

Thanks for your help.

Answer 1

IEnumerable does not support additions, if you want to able to add you can use IList or ICollection for Containers property type. If you want to stick with IEnumerable - you can create new one via Concat (or Append to add single element) and assign it to Containers:

IEnumerable<ContainerB> toAdd = ...; //  lots of ContainerB.TestString
contA.Containers = contA.Containers
    .Concat(toAdd);