Adding JArray to an existing property

Question

I have this JSON:

{
  "ID":123,
  "Products":null,
  "Title":"Products"
}

I want to add some data from DB to the "Products" node so my final json will look like so:

{
  "ID":123,
  "Products":[
      {
        "ID":1,
        "Name":"AA"
      },
      {
        "ID":2,
        "Name":"BB"
      }
    ],
  "Title":"Products"
}

I'm using this code:

internal class Product
{
    public int ID { get; set; }
    public string Name { get; set; }
}

//simulate DB
var products= new List<Product>()
{
    new Product() {ID=1,Name="AA" },
    new Product() {ID=2,Name="BB" }
};

string JSONstr = FilesUtils.OpenFile(Path.Combine(Environment.CurrentDirectory, "Sample.json"));
JObject JSON = JObject.Parse(JSONstr);
        ((JValue)JSON["Products"]).Value = JObject.FromObject(products);

But I get an exception:

Object serialized to Array. JObject instance expected.

`JSON["Products"] = JToken.FromObject(products);` should work. — dbc, Jun 28 '17 at 08:48
you the king ! - BTW how can i add new property to the root then? — Izikon, Jun 28 '17 at 08:51
The same way - just do `JSON["NewName"] = JToken.FromObject(newValue);` — dbc, Jun 28 '17 at 08:51

score 1 · Answer 1 · answered Jun 28 '17 at 08:55

You can do:

JSON["Products"] = JToken.FromObject(products);

To add a new property, do the same thing, e.g.:

JSON["TimeStamp"] = JToken.FromObject(DateTime.UtcNow);

Notes:

The item setter for JObject will add or replace the property with the specified name "Products".
JToken.FromObject() serializes any .Net object to a LINQ to JSON hierarchy. JToken is the abstract base class of this hierarchy and so can represent both arrays, objects, and primitives. See here for details.

Sample fiddle.

score 0 · Answer 2 · answered Jun 29 '17 at 08:21

The expected object will have to be (according to your JSON). If that's the JSON you want you might consider wrapping it up and adding the ID and a Title as shown in the JSON.

public class Product
{
    public int ID { get; set; }
    public string Name { get; set; }
}

public class YourObject
{
    public int ID { get; set; }
    public List<Product> Products { get; set; }
    public string Title { get; set; }
}

Adding JArray to an existing property

2 Answers2