How to create an array in JSON?

Question

How can I post an HTTP request like this? I tried to make something like this, but I don't know how to make the [] section. Thanks for help!

{
  "ID": 1,
  "calls": [
    {
      "number": 702061966,
      "duration": "00:02:21",
      "date" : "2020-11-26 12:45:00"
    },
    {
      "number" : 123456789,
      "duration" : "00:15:48",
      "date" : "2020-11-27 08:23:00"
      },
      {
      "number" : 123456789,
      "duration" : "00:09:33",
      "date" : "2020-11-28 16:02:00"
    }
  ]
}

Answer 1

First you need a structure to represent the data in C#. For the given JSON this may look like so:

public record MyRequest(int ID, IEnumerable<MyItem> Calls);
public record MyItem(int Number, string Duration, string Date);

Now you create the request

var req = new MyRequest(1, new List<MyItem> {
  new MyItem(702061966, "00:02:21", "2020-11-26 12:45:00"),
  ...
});

... and send it

var response = await httpClient.PostAsJson("some/url", req);

Code examples are intended as a first orientation and not tested. You can read more about it here:

• Records: https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-9#record-types
• HttpClient: https://learn.microsoft.com/en-us/dotnet/api/system.net.http.httpclient?view=net-5.0
• PostAsJson(): https://learn.microsoft.com/en-us/dotnet/api/system.net.http.json.httpclientjsonextensions.postasjsonasync?view=net-5.0
• JSON: https://www.json.org/json-en.html

I dont know how to make [] section

Any collection (IEnumerable<>, List<>, ...) will serialize to JSON list.

Notes:

• Code examples use c# 9 features
• You may want to use other data types than strings e.g. DateTime