Custom ASP.Net Core JSON model binder

My posted JSON object is this:

{{
 "emails": [
        {
          "To": "info@gmail.com",
          "Subject": "Subject",
          "Body": "Body",
          "ID": "d3d13242-6eff-4c57-b718-ef5ad49fe301"
        },
        {
          "To": "hr@gmail.com",
          "Subject": "Subject",
          "Body": "Body",
          "ID": "101edaf0-fcb4-48fc-9e9e-0d7492b591b0"
        }
      ]
}}

By default ASP.NET model binder will not bind this JSON object and as you can see here I get always null when I send post request to the API:

[HttpPost, Route("Send")]
public async Task<IActionResult> Send(Email[] emails)
{
  var toSave = from email in emails
                         select new EmailQueueItem
                         {
                             Html = true,
                             To = email.To,
                             Subject = email.Subject,
                             Body = email.Body
                         };

   await Database.BulkInsert(toSave.ToArray());

   return Ok();
 }

emails property is always null. I would appreciate any help for creating custom model binder that handel this kind of JSON objects.

The issue is that you are actually sending an object containing one property named emails, not an array, to the controller

Option one: The client object needs to contain just the array

 [
    {
      "To": "info@gmail.com",
      "Subject": "Subject",
      "Body": "Body",
      "ID": "d3d13242-6eff-4c57-b718-ef5ad49fe301"
    },
    {
      "To": "hr@gmail.com",
      "Subject": "Subject",
      "Body": "Body",
      "ID": "101edaf0-fcb4-48fc-9e9e-0d7492b591b0"
    }
  ]

Then read the array from the request body

public async Task<IActionResult> Send([FromBody]Email[] emails)

Option 2: When you define the array like this in the client

{
  "emails":...
}

You need to match that object setup on the controller by defining a model which contains a property called emails

public class RequestModel
{
    public Email[] emails { get; set; }
}

Then in the controller method, use the model and read it from the body

public async Task<IActionResult> Send([FromBody]RequestModel emails)