We Keep Coding

Elegant way to access first child using JSON.NET

I'm a bit confused with the Newtonsoft.Json JObject interface. Say I need to access the 'foo' property of the first child in my JSON object. My C# code:
string json = #"{
'someUnknownKey': { 'foo': 'bar' }
}";
JObject o = JObject.Parse(json);
JObject child = o.First.ToObject<JProperty>().Value.ToObject<JObject>();
string s = child["foo"].ToObject<string>();
This works, but is there a more elegant way to do it, without all the JProperty/JObject conversions?
EDIT: I would like to stress that the key name someUnknownKey is unknown so I can't use it in my code.

I believe you do need a conversion to indicate that you expect the first child token to be a property, but you can do it more simply than your current code:
string json = #"{
'someUnknownKey': { 'foo': 'bar' }
}";
JObject root = JObject.Parse(json);
Console.WriteLine(((JProperty) root.First).Value["foo"]);
Or to break it down slightly more clearly:
JObject root = JObject.Parse(json);
JProperty property = (JProperty) root.First;
Console.WriteLine(property.Value["foo"]);
Another option is to use the Properties() method to ask for the first property instead of the first child token. That way you don't need any conversion.
JObject root = JObject.Parse(json);
Console.WriteLine(root.Properties().First().Value["foo"]);

You can do something like this.
var jtk = o.Descendants().First().Children().First().Value<string>("foo")

You can query the json object as dynamic:
string json = #"{
'someUnknownKey': { 'foo': 'bar' }
}";
dynamic o = JArray.Parse(json);
string child = o.someUnknownKey.foo;
Look here for a reference https://www.newtonsoft.com/json/help/html/QueryJsonDynamic.htm
Alternatively you can use [] to access json properties:
JObject o = JObject.Parse(json);
string value = (string)(o['someUnknownKey']['foo']);

Newtonsoft's JObject: read any property using a string expression

I have a JObject and want to get any property or array element coming from a string expression.
I already know how to do it explicitly, like:
jObject["a"][0]["b");
But I would like to do something like: jObject("a[0].b");
The reason is that I am allowing the user to specify what to gather from the JSON object, rather than hardcoding the operation.

You can use SelectToken
string json = #"{a:[{b:1}]}";
var jobj = JObject.Parse(json);
var token = jobj.SelectToken("a[0].b");
Console.WriteLine(token);

Dynamic variable not working in C# with Json.Net

Can anyone tell me why I get an error when trying to output"dJson2.Type" in the code below?
string Json1= #"[{'Id':1, 'FirstName':'John', 'LastName':'Smith'}, {'Id':2, 'FirstName':'Jane', 'LastName':'Doe'}]";
dynamic dJson1= JsonConvert.DeserializeObject(Json1);
Console.WriteLine(dJson1.GetType());
Console.WriteLine(dJson1.Type);
string Json2 = #"{'Id':1, 'FirstName':'John', 'LastName':'Smith'}";
dynamic dJson2 = JsonConvert.DeserializeObject(Json2);
Console.WriteLine(dJson2.GetType());
Console.WriteLine(dJson2.Type);
The program dies on the Console.WriteLine(dJson2.Type) statement. The output of the program is...
Newtonsoft.Json.Linq.JArray
Array
Newtonsoft.Json.Linq.JObject
(should say Object here, I think)
Inspecting the local variables, dJson2 has a "Type" property with value "Object".

This is because JObject behaves similarly as System.Dynamic.ExpandoObject. Try to change your example to:
string Json2 = #"{'Id':1, 'FirstName':'John', 'LastName':'Smith'}";
dynamic dJson2 = JsonConvert.DeserializeObject(Json2);
dJson2.Type = "mynewfield";
Console.WriteLine(dJson2.GetType());
Console.WriteLine(dJson2.Type);
If you want to get property of underlying type you need to cast it (to JToken or JObject), otherwise requested property will be searched in
IDictionary<string, JToken> that JObject implements.
This example may help:
dynamic oobj = new JObject();
oobj.Type = "TEST";
Console.WriteLine(oobj.Type);
Console.WriteLine(((JObject)oobj).Type);

how to deserialize an anonymus object in c# [duplicate]

Is it possible to return a dynamic object from a json deserialization using json.net? I would like to do something like this:
dynamic jsonResponse = JsonConvert.Deserialize(json);
Console.WriteLine(jsonResponse.message);

Json.NET allows us to do this:
dynamic d = JObject.Parse("{number:1000, str:'string', array: [1,2,3,4,5,6]}");
Console.WriteLine(d.number);
Console.WriteLine(d.str);
Console.WriteLine(d.array.Count);
Output:
1000
string
6
Documentation here: LINQ to JSON with Json.NET
See also JObject.Parse and JArray.Parse

As of Json.NET 4.0 Release 1, there is native dynamic support:
[Test]
public void DynamicDeserialization()
{
dynamic jsonResponse = JsonConvert.DeserializeObject("{\"message\":\"Hi\"}");
jsonResponse.Works = true;
Console.WriteLine(jsonResponse.message); // Hi
Console.WriteLine(jsonResponse.Works); // True
Console.WriteLine(JsonConvert.SerializeObject(jsonResponse)); // {"message":"Hi","Works":true}
Assert.That(jsonResponse, Is.InstanceOf<dynamic>());
Assert.That(jsonResponse, Is.TypeOf<JObject>());
}
And, of course, the best way to get the current version is via NuGet.
Updated (11/12/2014) to address comments:
This works perfectly fine. If you inspect the type in the debugger you will see that the value is, in fact, dynamic. The underlying type is a JObject. If you want to control the type (like specifying ExpandoObject, then do so.

If you just deserialize to dynamic you will get a JObject back. You can get what you want by using an ExpandoObject.
var converter = new ExpandoObjectConverter();
dynamic message = JsonConvert.DeserializeObject<ExpandoObject>(jsonString, converter);

I know this is old post but JsonConvert actually has a different method so it would be
var product = new { Name = "", Price = 0 };
var jsonResponse = JsonConvert.DeserializeAnonymousType(json, product);

Yes you can do it using the JsonConvert.DeserializeObject. To do that, just simple do:
dynamic jsonResponse = JsonConvert.DeserializeObject(json);
Console.WriteLine(jsonResponse["message"]);

Note: At the time I answered this question in 2010, there was no way to deserialize without some sort of type, this allowed you to deserialize without having go define the actual class and allowed an anonymous class to be used to do the deserialization.
You need to have some sort of type to deserialize to. You could do something along the lines of:
var product = new { Name = "", Price = 0 };
dynamic jsonResponse = JsonConvert.Deserialize(json, product.GetType());
My answer is based on a solution for .NET 4.0's build in JSON serializer. Link to deserialize to anonymous types is here:
http://blogs.msdn.com/b/alexghi/archive/2008/12/22/using-anonymous-types-to-deserialize-json-data.aspx

If you use JSON.NET with old version which didn't JObject.
This is another simple way to make a dynamic object from JSON:
https://github.com/chsword/jdynamic
NuGet Install
PM> Install-Package JDynamic
Support using string index to access member like:
dynamic json = new JDynamic("{a:{a:1}}");
Assert.AreEqual(1, json["a"]["a"]);
Test Case
And you can use this util as following :
Get the value directly
dynamic json = new JDynamic("1");
//json.Value
2.Get the member in the json object
dynamic json = new JDynamic("{a:'abc'}");
//json.a is a string "abc"
dynamic json = new JDynamic("{a:3.1416}");
//json.a is 3.1416m
dynamic json = new JDynamic("{a:1}");
//json.a is integer: 1
3.IEnumerable
dynamic json = new JDynamic("[1,2,3]");
/json.Length/json.Count is 3
//And you can use json[0]/ json[2] to get the elements
dynamic json = new JDynamic("{a:[1,2,3]}");
//json.a.Length /json.a.Count is 3.
//And you can use json.a[0]/ json.a[2] to get the elements
dynamic json = new JDynamic("[{b:1},{c:1}]");
//json.Length/json.Count is 2.
//And you can use the json[0].b/json[1].c to get the num.
Other
dynamic json = new JDynamic("{a:{a:1} }");
//json.a.a is 1.

Yes it is possible. I have been doing that all the while.
dynamic Obj = JsonConvert.DeserializeObject(<your json string>);
It is a bit trickier for non native type. Suppose inside your Obj, there is a ClassA, and ClassB objects. They are all converted to JObject. What you need to do is:
ClassA ObjA = Obj.ObjA.ToObject<ClassA>();
ClassB ObjB = Obj.ObjB.ToObject<ClassB>();

JObject how to read values in the array?

This is the json string:
{"d":[{"numberOfRowsAdded":"26723"}]}
string json = DAO.getUploadDataSummary();
JObject uploadData = JObject.Parse(json);
string array = (string)uploadData.SelectToken("d");
How do I change the code to reader the values in 'numberOfRowsAdded?

JObject uploadData = JObject.Parse(json);
int rowsAdded = Convert.ToInt32((string)uploadData["d"][0]["numberOfRowsAdded"])

You need to cast to JArray:
string json = "{\"d\":[{\"numberOfRowsAdded\":\"26723\"}]}";
JObject parsed = JObject.Parse(json);
JArray array = (JArray) parsed["d"];
Console.WriteLine(array.Count);

You can cast your JObject as a dynamic object.
You can also cast your array to JArray object.
JObject yourObject;
//To access to the properties in "dot" notation use a dynamic object
dynamic obj = yourObject;
//Loop over the array
foreach (dynamic item in obj.d) {
var rows = (int)item.numberOfRowsAdded;
}

I played around with writing a generic method that can read any part of my json string. I tried a lot of the answers on this thread and it did not suit my need. So this is what I came up with. I use the following method in my service layer to read my configuration properties from the json string.
public T getValue<T>(string json,string jsonPropertyName)
{
var parsedResult= JObject.Parse(json);
return parsedResult.SelectToken(jsonPropertyName).ToObject<T>();
}
and this is how you would use it :
var result = service.getValue<List<string>>(json, "propertyName");
So you can use this to get specific properties within your json string and cast it to whatever you need it to be.