JSON.NET Adding to JArray

Question

I've got a json array that I want to add to, then write the content to a file. I have no problem adding the content to the array, but writing to file using the JsonSerializer.Serialize method gives me the exception:

ArgumentException: Can not add Newtonsoft.Json.Linq.JObject to Newtonsoft.Json.Linq.JObject.

This occurs on the last line of my code below. "jSerializer.Serialize(o.CreateWriter(), o);"

JSON

{
"ArrayToManipulate":
[
    {
        "Name":"Value"
    },
    {
        "Name":"value"
    }
]
}

Code to manipulate the JSON Objects

JContainer o = (JObject)JToken.ReadFrom(new JsonTextReader(reader));
JArray x = (JArray)o["ArrayToManipulate"];
ContentObject newObject = new ContentObject(){Name="Value"};
JToken tokenToAdd = JToken.Parse(JsonConvert.SerializeObject(newObject, Formatting.Indented));
x.Add(tokenToAdd);
JsonSerializer jSerializer = new JsonSerializer();
jSerializer.Converters.Add(new Newtonsoft.Json.Converters.StringEnumConverter());
jSerializer.Serialize(o.CreateWriter(), o);

Am I going about this the wrong way?

carlosfigueira · Accepted Answer · 2013-12-10 04:52:15Z

1

The writer you get by calling JContainer.CreateWriter doesn't write to a file as you want - it is a writer to write to the container itself. You need something like the code below - create a "regular" text writer based on a file, then a JsonWriter based on that.

const string JSON = "{\"ArrayToManipulate\":[{\"Name\":\"Value\"},{\"Name\":\"value\"}]}";
var reader = new StringReader(JSON);
JContainer o = (JObject)JToken.ReadFrom(new JsonTextReader(reader));
JArray x = (JArray)o["ArrayToManipulate"];
ContentObject newObject = new ContentObject() { Name = "Value" };
JToken tokenToAdd = JToken.Parse(JsonConvert.SerializeObject(newObject, Formatting.Indented));
x.Add(tokenToAdd);
JsonSerializer jSerializer = new JsonSerializer();
jSerializer.Converters.Add(new Newtonsoft.Json.Converters.StringEnumConverter());
using (var w = File.CreateText(@"C:\temp\a.json"))
{
    using (var jw = new JsonTextWriter(w))
    {
        jSerializer.Serialize(jw, o);
    }
}

answered Dec 10, 2013 at 4:52

carlosfigueira

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1 Comment

Kiquenet Over a year ago

And how **DE-Serialize" from a a.json file ?

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