Fluent interface issue with adding multiple elements

Question

I have the following code (from mailgun_csharp):

var message = new MessageBuilder()
            .SetSubject(Subject)
            .SetFromAddress(new Recipient { Email = From.Address, DisplayName = From.DisplayName })
            .SetHtmlBody(Body)
            .AddToRecipient(new Recipient { Email = "a@a.com", DisplayName = "a" })
            .GetMessage();

so far, so good...

now I want to add 2 recipients:

var message = new MessageBuilder()
            .SetSubject(Subject)
            .SetFromAddress(new Recipient { Email = From.Address, DisplayName = From.DisplayName })
            .SetHtmlBody(Body)
            .AddToRecipient(new Recipient { Email = "a@a.com", DisplayName = "a" })
            .AddToRecipient(new Recipient { Email = "b@a.com", DisplayName = "b" })
            .GetMessage();

this works well too...

but if I have a List and I want to add the whole list to .AddRecipient, how can I do that programmatically?

Answer 1

It looks like mailgun_csharp library lacks a method for passing a list of recipients to the API. C# lets you fix this shortcoming by adding your own implementation as an extension:

public static class MessageBuilderExtensions {
    public static IMessageBuilder AddToRecipients(
        this IMessageBuilder builder
    ,   IEnumerable<IRecipient> recipients
    ,   JObject recipientVariables = null) {
        foreach (var recipient in recipients) {
            builder = builder.AddRecipient(recipient, recipientVariables);
        }
        return builder;
    }
}

Now you can write this code:

IEnumerable<IRecipient> myListOfRecipients = ...
var message = new MessageBuilder()
    .SetSubject(Subject)
    .SetFromAddress(new Recipient { Email = From.Address, DisplayName = From.DisplayName })
    .SetHtmlBody(Body)
    .AddToRecipients(myListOfRecipients)
    .GetMessage();