In the previous post we saw how to use CrmServiceClient to connect to CDS using Authentication Type – OAuth and execute web request using Organization.svc service

https://nishantrana.me/2020/11/09/sample-code-to-connect-to-cds-dynamics-365-ce-using-oauth/

Here we will extend the same example to execute web request using Web API.

• Create the contact record with first name and last name populated

using Microsoft.Xrm.Tooling.Connector;
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;

namespace SampleConsoleApp
{
class Program
{
static void Main(string[] args)
{
string ConnectionString = "AuthType = OAuth; " +
"Username = [username]@[domain].onmicrosoft.com;" +
"Password = [password]; " +
"Url = https://[orgname].crm.dynamics.com;" +
"AppId=51f81489-12ee-4a9e-aaae-a2591f45987d;" +
"RedirectUri=app://58145B91-0C36-4500-8554-080854F2AC97;" +
"LoginPrompt=Auto";

CrmServiceClient svc = new CrmServiceClient(ConnectionString);

// specify OData Headers
Dictionary<string, List<string>> odataHeaders = new Dictionary<string, List<string>>
{
{ "Accept", new List<string>() { "application/json" } },
{ "OData-MaxVersion", new List<string>() { "4.0" } },
{ "OData-Version", new List<string>() { "4.0" } }
};

if (svc.IsReady)
{
// create a contact record with firstname and lastname populated
dynamic contact = new JObject();
contact.firstname = "Meeska";
contact.lastname = "Mooska";
string jsonContact = Newtonsoft.Json.JsonConvert.SerializeObject(contact);

// create the contact record
// Parameters - HttpMethod, QueryString, Body, Customer Headers, Content Type
HttpResponseMessage httpResponse = svc.ExecuteCrmWebRequest(
HttpMethod.Post,
"contacts",
jsonContact,
odataHeaders,
"application/json");

if (httpResponse.IsSuccessStatusCode)
{
var contactUri = httpResponse.Headers.GetValues("OData-EntityId").FirstOrDefault();
Console.WriteLine("Contact URI: {0}", contactUri);
}
else
{
Console.WriteLine(httpResponse.ReasonPhrase);
}
}
}
}
}

• Retrieve first name and last name for all the contact

// retrieve first name and last name of all the contact records 
HttpResponseMessage httpResponse = svc.ExecuteCrmWebRequest(
HttpMethod.Get,
"contacts?$select=firstname,lastname",
string.Empty,
odataHeaders,
"application/json");

Refer appropriate connection string as required with CrmServiceClient- 

https://docs.microsoft.com/en-us/powerapps/developer/data-platform/xrm-tooling/use-connection-strings-xrm-tooling-connect#connection-string-examples

Sample Code – Dynamics 365 Web API / Organization Service

Get the details here – ExecuteCrmWebRequest

Hope it helps..