Access JSON keys in C# from ServiceNow Rest API

Question

I am calling the ServiceNow Incidents table and pulling back one incident like this. https://mydevInstance.service-now.com/api/now/v1/table/incident?sysparm_limit=1

var client = new RestClient("https://mydevInstance.service-now.com/api/now/v1/table/incident?sysparm_limit=1");
client.Timeout = -1;
var request = new RestRequest(Method.GET);
request.AddHeader("Authorization", "Basic myAuthKey");
IRestResponse response = client.Execute(request);

The JSON it returns in RESTSharp looks like this.

{
    "result": [
        {
            "parent": "",
            "made_sla": "true",
            "caused_by": "",
            "watch_list": "",
            "upon_reject": "cancel",
            "resolved_by": {
                "link": "https://mydevInstance.service-now.com/api/now/v1/table/sys_user/5137153cc611227c000bbd1bd8cd2007",
                "value": "5137153cc611227c000bbd1bd8cd2007"
            },
            "approval_history": "",
            "number": "INC0000060"
        }
    ]
}

How do I create a C# list or array of all the Keys under result? I can't Serialize the object with JSON.Net because additional keys can be added over time.

Depending on what version of Visual Studio you are using, you should have a "Paste" option that allows you to 'paste' some JSON (or XML) as a C# class. This feature may also be under "Paste Special" ... check your "Edit" menu — Glenn Ferrie, Dec 21 '20 at 18:15
That doesn't work in this instance as the class would change when additional columns are added to the incident, which results in additional keys added to the JSON. I need the list of keys. — TMAC 23, Dec 21 '20 at 18:33
When the table in service now changes, you will need to make appropriate changes to the class. — Jawad, Dec 21 '20 at 19:25
I don't want/need a class. I just need a list, string, or array of all the keys from JSON. — TMAC 23, Dec 21 '20 at 19:43

Glenn Ferrie · Answer 1 · 2020-12-23T04:18:23.313

You need to grab the sample of the JSON content, then make a C# class using the 'Paste Special' option I described.

Then you can use the JsonConvert.DeserializeObject<T> (in a nuget package by Newtonsoft) to deserialize your web service response in a C# object instance.

Here are the C# classes I generated with your JSON object unaltered:

public class Rootobject
{
    public Result[] result { get; set; }
}

public class Result
{ 
    public string parent { get; set; }
    public string made_sla { get; set; }
    public string caused_by { get; set; }
    public string watch_list { get; set; }
    public string upon_reject { get; set; }
    public Resolved_By resolved_by { get; set; }
    public string approval_history { get; set; }
    public string number { get; set; }
}

public class Resolved_By
{
    public string link { get; set; }
    public string value { get; set; }
}

You use this type like this:

var json = "t-b-d"; // From Web Service call
Rootobject response = JsonConvert.DeserializeObject<Rootobject>(json);
// use the response object.

** UPDATED **

If you need a more flexible model, all JSON will deserialize into Dictionary<string, string>, but I have found that serialization / deserialization results are more reliable when the model is consistent

var response = JsonConvert.DeserializeObject<Dictionary<string,string>>(json);

That doesn't work in this instance as the class would change when additional columns are added to the incident, which results in additional keys added to the JSON. I need the list of keys. — TMAC 23, Dec 21 '20 at 18:57
List of keys are going to depend on your service now table. Normally I go to the site in Chrome to get all fields and create a class based on that — Jawad, Dec 21 '20 at 19:22
The list is going to be different for each company that uses it. I need the list of keys programmatically. — TMAC 23, Dec 21 '20 at 19:47
@Glenn still didn't work as it throws an error Unexpected character encountered while parsing value: [. Path 'result', line 1, position 11. — TMAC 23, Dec 23 '20 at 18:39

score 1 · Accepted Answer · answered Dec 23 '20 at 18:43

Here is what does work using System.Text.Json

var incidentFields = new List<string>();

var doc = JsonDocument.Parse(json);
foreach (var o in doc.RootElement.GetProperty("result").EnumerateArray())
{
    foreach (var p in o.EnumerateObject())
    {
        incidentFields.Add(p.Name.ToString());
    }
}

Emerson Bottero · Answer 3 · 2022-07-24T02:40:01.030

0

I created a library that handles that by default. (You can add custom types also)

https://autodati.github.io/ServiceNow.Core/

edited Jul 24 '22 at 02:40

answered Jan 21 '22 at 23:47

Emerson Bottero

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Access JSON keys in C# from ServiceNow Rest API

3 Answers3