CODEWITHSUNDEEP
c#json.net
vvv444
vvv444

Reputation: 3122

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.

Upvotes: 2

Views: 4370

Answers (3)

mr100
mr100

Reputation: 4428

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']);

Upvotes: -1

dotnetstep
dotnetstep

Reputation: 17485

You can do something like this.

var jtk = o.Descendants().First().Children().First().Value<string>("foo")

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1502246

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"]);

Upvotes: 3

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