CODEWITHSUNDEEP
c#jsonlinq
Santosh K
Santosh K

Reputation: 43

Getting Exception while accessing value of JToken - Cannot access child value on Newtonsoft.Json.Linq.JValue

I am working on a test case to emulate my C# method. I am unable to access the DocumentID property of the JToken using token["DocumentID"]. I am getting System.InvalidOperationException - "Cannot access child value on Newtonsoft.Json.Linq.JValue".

string response = "[\r\n  \"{ \\\"DocumentID\\\": \\\"fakeGuid1\\\",\\\"documentNotes\\\": \\\"TestNotes1\\\"}\"\r\n]";
//Response has escape charaters as  this is being returned by a mockMethod which is supposed to return JSon.ToString().

string[] fakeGuidForExecutiveSummary = new string[]{"fakeGuid1"};
string fakeResponseFromExecutiveSummaryProxy = "{ \"DocumentID\": \"fakeGuid1\",\"documentNotes\": \"TestNotes1\"}";

JArray jsonResponse = JArray.Parse(response);
//Value of jsonResponse from Debugger - {[  "{ \"DocumentID\": "fakeGuid1\",\"documentNotes\": \"TestNotes1\"}" ]}

JToken token = jsonResponse[0];
//Value of token from Debugger - { "DocumentID": fakeGuid1","documentNotes": "TestNotes1"}
Assert.AreEqual(fakeGuidForExecutiveSummary[0], token["DocumentID"]);

Upvotes: 4

Views: 18608

Answers (1)

dbc
dbc

Reputation: 116595

You don't show how you initialize fakeGuidForExecutiveSummary. Assuming you do it in the following way:

        string fakeResponseFromExecutiveSummaryProxy = "{ \"DocumentID\": \"fakeGuid1\",\"documentNotes\": \"TestNotes1\"}";
        var fakeResponse = JToken.Parse(fakeResponseFromExecutiveSummaryProxy);
        var fakeGuidForExecutiveSummary = fakeResponse["DocumentID"];

Then the problem is that fakeGuidForExecutiveSummary is a JValue, not a JToken or JArray. Your code will throw the exception you see if you try to access a (nonexistent) child value by index.

Instead you need to do the following:

        string response = @"[{ ""DocumentID"": ""fakeGuid1"",""documentNotes"": ""TestNotes1""}]";
        JArray jsonResponse = JArray.Parse(response);
        JToken token = jsonResponse[0];

        //Value of token from Debugger - { "DocumentID": fakeGuid1","documentNotes": "TestNotes1"}
        Assert.AreEqual(fakeGuidForExecutiveSummary, token["DocumentID"])

Update

Given your updated code, the problem is that your sample JSON response has too many levels of string escaping: \\\"DocumentID\\\". You probably copied escaped strings shown in Visual Studio into the source code, then escaped them some again.

Change it to

        string response = "[\r\n  { \"DocumentID\": \"fakeGuid1\",\"documentNotes\": \"TestNotes1\"}\r\n]";

Upvotes: 1

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