REST Client for ServiceNow's TableAPI for GET call in C#

Satish Babu · ‎05-18-2020

Hello there,

Working with the Web Developer in integrating our ServiceNow platform with there WebApp.

As part of the development, we need a batch job that would query a list of records from the ServiceNow table and update curtains values in there WebApp.

But we unable to query the list of records using SNOW Table API for a specific date.

Can you someone help us with the C# code to get a list of records from a table for a specific date or a date range.

C# code the Web Developer has written.

var client = new RestClient(Instanceurl+ "/api/now/table/incident?sysparm_limit=15");

client.Authenticator = new HttpBasicAuthenticator(user, password);

var request = new RestRequest("incident", Method.GET);

request.AddParameter("sys_updated_on", "2020-02-18 19:23:22");

//Works but only when I pass the specific DateTime value.

request.RequestFormat = DataFormat.Json;

IRestResponse response = client.Execute(request);

dynamic _result = JsonConvert.DeserializeObject<RestAPIResult.ChildrenRootObject>(response.Content.ToString());

if (_result.result.Count > 0) //Important to prevent "Object reference not set to an instance of an object" error.

{

Simon Christens · ‎05-18-2020

Hi Satish

I have been like 15 years since i worked with C# but it should be possible to you duo to ServiceNow's input.

I would suggest that you use ServiceNows query builder to make you initial queries and then build them in your C# app

These are examples for different inputs for ServiceNow to filter in either periods or "today" as examples

query["sysparm_query"] = "sys_updated_onBETWEENjavascript:gs.dateGenerate('2020-03-01','00:00:00')@javascript:gs.dateGenerate('2020-05-17','00:00:00')";
query["sysparm_query"] = "sys_updated_on>=javascript:gs.beginningOfToday()";

And then:

Below is a C# sample that should return the correct incidents from a given period or date of these examples

using System;
using System.Net.Http;
using System.Text;
using System.Web;
using System.Collections.Generic;

namespace cs_test
{
    internal class Program
    {
        internal static void Main(string[] args)
        {
            byte[] byteArray = Encoding.ASCII.GetBytes("username:password");

            UriBuilder builder = new UriBuilder("https://instance.service-now.com/api/now/table/incident");

            var query = HttpUtility.ParseQueryString(builder.Query);
            query["sysparm_limit"] = "15";
            query["sysparm_fields"] = "number,short_description";
            query["sysparm_query"] = "sys_updated_onBETWEENjavascript:gs.dateGenerate('2020-03-01','00:00:00')@javascript:gs.dateGenerate('2020-05-17','00:00:00')";
            //query["sysparm_query"] = "sys_updated_on>=javascript:gs.beginningOfToday()";
            builder.Query = query.ToString();
            string url = builder.ToString();
            
            Console.WriteLine(url);

            GetRequst(url, byteArray);

            Console.ReadKey();
        }

        async static void GetRequst(string url, byte[] byteArray){

            using (HttpClient client = new HttpClient()){

                client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Basic", Convert.ToBase64String(byteArray));
                

                using (HttpResponseMessage response = await client.GetAsync(url)){

                    using(HttpContent content = response.Content){

                        string myContent = await content.ReadAsStringAsync();
                        var records = Newtonsoft.Json.JsonConvert.DeserializeObject<RootObject>(myContent);
   
                        Console.WriteLine(records.result.Count);

                        foreach(Record rec in records.result){

                            Console.WriteLine(rec.number + " - " + rec.short_description);
                        }        

                    }
                }
            }
        }
    }
    internal class RootObject{
        public List<Record> result { get; set; }
    }

    internal class Record{

        public string number { get; set; }
        public string short_description { get; set; }

    }
}

View solution in original post

hanaphouse · ‎05-18-2020

I would recommend creating your own Scripted REST API (System Web Services > Scripted Web Service > Scripted REST API) to give you more control on what query parameters your API need and what data would you want it to return and it what format.

Here's a sample. In this sample, the query would require the table name and incident number then return some data:

Response Body:

Sema A · ‎05-20-2020

I am having problem with executing the Console.ReadKey(); code from task scheduler. Does anybody have a solution how to process this request? Thanks

GetRequest(url,byteArray);
Console.ReadKey();

Simon Christens · ‎05-21-2020

Hi Sema

Console.ReadKey() is used to track user inputs so its properly not needed for your solution

https://docs.microsoft.com/en-us/dotnet/api/system.console.readkey?view=netcore-3.1

I used it in the example cause i used Visual studio code for the example

Sema A · ‎05-22-2020

Thats what I thought but we were unable to execute this method without this line. My co-worker found a way to run the RESTAPI query for date range with simple method if it helps anybody. Thank you for your help and support Simon.

var client = new RestClient(APIURL + "/api/now/table/<table Name>?");
client.Authenticator = new HttpBasicAuthenticator(<username>, <Password>);
var request = new RestRequest("alm_asset", Method.GET);
// request.AddParameter("sysparm_limit", MaxRows);
request.AddParameter("sysparm_query", "sys_updated_on>=javascript:gs.beginningOfToday(0)");

IRestResponse response = client.Execute(request);
dynamic _result = JsonConvert.DeserializeObject<RestAPIResult.ChildrenRootObject>(response.Content.ToString());

if (_result.result.Count > 0) {}