Unable to cast object of type 'Newtonsoft.Json.Linq.JObject' to type 'Newtonsoft.Json.Linq.JArray'

I am testing my Web API. Mocking the data I have this:

var objs = ((JArray)JsonConvert.DeserializeObject("{ \"PrintId\":10,\"Header\":\"header\",\"TC\":\"tc\",\"CompanyRef\":\"00000000-0000-0000-0000-000000000000\"}")).Values<JObject>(); 

Which gives me the error:

Unable to cast object of type 'Newtonsoft.Json.Linq.JObject' to type 'Newtonsoft.Json.Linq.JArray'

The thing is it was working. I must have changed something, but I don't know what.

My intent is to convert this JSON object to a list of .NET objects called Print which has the fields:

PrintId Header TX CompnayRef 

4 Answers

Just make a class and deserialize it.

public class Print { public int PrintId { get; set; } public string Header { get; set; } public string TC { get; set; } public string CompanyRef { get; set; } } Print printObj = JsonConvert.DeserializeObject<Print>(yourJson); printObj.PrintId = //... 

As the message says, your object is JObject so don't cast it to JArray. Try this:

var objs = JsonConvert.DeserializeObject("{ \"PrintId\":10,\"Header\":\"header\",\"TC\":\"tc\",\"CompanyRef\":\"00000000-0000-0000-0000-000000000000\"}"); 

Update To get a collection List<Print>, your JSON needs to be an array. Try this (I made your JSON an array and added a second object):

string json = "[{ \"PrintId\":10,\"Header\":\"header\",\"TC\":\"tc\",\"CompanyRef\":\"00000000-0000-0000-0000-000000000000\"}" + ",{ \"PrintId\":20,\"Header\":\"header2\",\"TC\":\"tc2\",\"CompanyRef\":\"00000000-0000-0000-0000-000000000000\"}]"; var objs = JsonConvert.DeserializeObject<List<Print>>(json); //The loop is only for testing. Replace it with your code. foreach(Print p in objs){ Console.WriteLine("PrintId: " + p.PrintId); Console.WriteLine("Header: " + p.Header); Console.WriteLine("TC: " + p.TC); Console.WriteLine("CompanyRef: " + p.CompanyRef); Console.WriteLine("=============================="); } public class Print { public int PrintId { get; set; } public string Header { get; set; } public string TC { get; set; } public string CompanyRef { get; set; } } 

Here is a fiddle.

Simply because { } is a jobject notation, to make it a jarray just put square brackets around it e.g. [{ }]. So in your case, just putting these two chars fixes the problem.

var objs = ((JArray)JsonConvert.DeserializeObject("[{ \"PrintId\":10,\"Header\":\"header\",\"TC\":\"tc\",\"CompanyRef\":\"00000000-0000-0000-0000-000000000000\"}]")).Values<JObject>(); 

you can try here

Note: You said it was working before. So this string input probably is a result of a serialization. You did not have a problem before, because your input was always an array with multiple items until this one. And your serializer is probably producing a single object (output starting with '{') instead of an array (output starting with '[') for single item arrays.

serializing List with single object as JSON object not JSON array

For me I was putting empty string as an object which caused the issue, I switched to "{}" which fixed my issue