Iterating through a nested JSON Array in C# with Newtonsoft

Question

I have a block of JSON as follows:

[
  {
    "id": 1,
    "name": "Section1",
    "project_id": 100,
    "configs": [
      {
        "id": 1000,
        "name": "myItem1",
        "group_id": 1
      }
    ]
  },
  {
    "id": 2,
    "name": "Section2",
    "project_id": 100,
    "configs": [
      {
        "id": 1001,
        "name": "myItem2",
        "group_id": 2
      },
      {
        "id": 1002,
        "name": "myItem3",
        "group_id": 2
      },
      {
        "id": 1003,
        "name": "myItem4",
        "group_id": 2
      }
    ]
  },
  {
    "id": 3,
    "name": "Section3",
    "project_id": 100,
    "configs": [
      {
        "id": 1004,
        "name": "myItem5",
        "group_id": 5
      },
    ]
  }
]

I have pulled it into Memory as a JArray.

I need to iterate through this such that I'm grabbing a list of ids and name from only the config sub-arrays. Ideally, I'll end up with something like this:

1000, myItem1
1001, myItem2
1002, myItem3
1003, myItem4
1004, myItem5

I'm having a hard time understanding what Newstonsoft calls a JObject vs a JArray, or how to access the various parts of each of those data structures. What I have right now is as follows:

foreach (JObject config in result["configs"])
{
    string id = (string)config["id"];
    string name = (string)config["name"];
    string gid = (string)config["group_id"];

    Console.WriteLine(name + " - " + id + " - " + gid);
}

This does not work, but I hope it illustrates what my end goal is. I've been unable to piece together how to accomplish this goal.

Please provide a minimal reproducible example. What is result? — ProgrammingLlama
– ProgrammingLlama, Commented Nov 22, 2017 at 1:30
The easy way is to define some classes for the structure - use the help of jsonutils.com - and deserialize the json into the classes. — Sir Rufo
– Sir Rufo, Commented Nov 22, 2017 at 1:42

ProgrammingLlama · Accepted Answer · 2017-11-22 01:52:15Z

24

A JObject is an object (analogous to a class):

{
    "a": 1,
    "b": true
}

A JArray is a JSON array, and contains multiple JObject entities:

[
    {
        "a": 1,
        "b": true
    },
    {
        "a": 2,
        "b": true
    }
]

The root of a JSON document can be an object, or an array. In your case, it's an array.

The following code and fiddle reveals that your code is fine, provided that you deserialize the document as what it is - an array.

string json = "[{\"id\":1,\"name\":\"Section1\",\"project_id\":100,\"configs\":[{\"id\":1000,\"name\":\"myItem1\",\"group_id\":1}]},{\"id\":2,\"name\":\"Section2\",\"project_id\":100,\"configs\":[{\"id\":1001,\"name\":\"myItem2\",\"group_id\":2},{\"id\":1002,\"name\":\"myItem3\",\"group_id\":2},{\"id\":1003,\"name\":\"myItem4\",\"group_id\":2}]},{\"id\":3,\"name\":\"Section3\",\"project_id\":100,\"configs\":[{\"id\":1004,\"name\":\"myItem5\",\"group_id\":5},]}]";
JArray obj = Newtonsoft.Json.JsonConvert.DeserializeObject<JArray>(json);
foreach (var result in obj)
{
    foreach (JObject config in result["configs"])
    {
        string id = (string)config["id"];
        string name = (string)config["name"];
        string gid = (string)config["group_id"];

        Console.WriteLine(name + " - " + id + " - " + gid);
    }
}

answered Nov 22, 2017 at 1:52

ProgrammingLlama

39.4k7 gold badges78 silver badges104 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

mkautzm Over a year ago

This has helped immensely to clear the confusion I had about the various object types -- I sincerely appreciate your time in typing this up!

Nafis Zaman Over a year ago

A minor clarification: A JArray can contain things other than JObjects. Specifically there could be JValues if the JSON array contains strings or other non-object values. This is why the type of result above is the more generic JToken instead of JObject

Jakobson Over a year ago

very useful thank you, I've spent too much time to introduce myself better with Json

Collectives™ on Stack Overflow

Iterating through a nested JSON Array in C# with Newtonsoft

1 Answer 1

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related