JObject.Parse key/value with json.net in C#

Question

Hey all I have the following code:

try {
  foreach (var x1 in JObject.Parse(json1)) {
     string name = x1.Key;
     JToken value = x1.Value;

There are no visible errors with the above code. However, once I run the application and it gets to that point it errors and says:

'Newtonsoft.Json.Linq.JProperty' does not contain a definition for 'Key'

So whats going on here. My VB.net code works like the above:

Try
    For Each x1 In JObject.Parse(json1)
       Dim name As String = x1.Key
       Dim value As JToken = x1.Value

Not sure why VB would work, nor why the compiler wouldn't catch it (unless that setup uses dynamic), but I believe the property you're looking for is actually Name. — Matthew Haugen
– Matthew Haugen, Commented Feb 1, 2016 at 21:19

Domysee · Accepted Answer · 2016-02-01 21:26:49Z

1

JProperty (you get JPropertys by iterating over a JObject) inherits from JContainer, which inherits from JToken. JToken implements IDynamicMetaObjectProvider.

This makes it essentially a dynamic object, which allows you to access anything on it at compile time. That's why you dont get a compiler error.

At runtime the DLR discovers that there is no Key property on x1 and throws that exception.

If you want to get the property name, you should use the Name property.

foreach (var x1 in JObject.Parse(json1)) {
    string name = x1.Name;
    JToken value = x1.Value;

edited Feb 1, 2016 at 21:26

answered Feb 1, 2016 at 21:21

Domysee

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