Integrating .Net and Salesforce using REST API

Step 1: Create your connected app in Salesforce Org.

• Go To Setup
• Quick find App Manager
• Click on New Connected App

• In Name, type SFIntegration, and supply a mandatory Contact Email
  Make sure Enable OAuth settings is ticked.
• In Callback URL, type your web project URL with https (e.g https://yourappname.com). Callback URL is used for OAuth flows.
• In Selected OAuth scopes, Add Access and manage your data (API)
• Click Save. We will get a message telling us to wait for a few minutes before using the app.
• Click Continue. The information for our connected app will be displayed. Take note of the Consumer Key, which we’ll use in the following steps.
• Click on the Click to Reveal link next to Consumer Secret. Write down the consumer secret that is displayed, as we’ll use it in the following steps.

Step 2: Create a new .Net Web Project

• We now have all the information we need to start coding our client app. In VisualStudio, create a new Web project, and add a new class, which we’ll call SalesforceClient.
• We will be using the new HttpClient class, which is the easiest way to make HTTP callouts. It offers great support for asynchronous calls, but for this post, we’ll be making the calls synchronous by calling the Result keyword.
• First, we will call the salesforce API for the Authentication. Once your customers’ data is recorded, it will be redirected to a Salesforce.com auth endpoint and you will have access granted through an endpoint. The idea is to transfer their Salesforce data on their behalf.
• After successful authentication with an endpoint, Salesforce will send a response with an Access and Refresh token. The Access token has an expiration date of 15 minutes and the Refresh token helps you get in when the Access is expired.

https://login.salesforce.com/services/oauth2/authorize?response_type=code&client_id=YOURCONSUMERID&redirect_uri=https://www.yourappname.com/salesforce/callback

• That’s the request you will make as an initial authorization. The client_id will be your consumer ID from the connected app and the redirect_uri will be the Callback URL. When you have a successful response, your user will login and authenticate.
• Once the data is authorized, Salesforce will add an authorization code to the URL, creating a request that looks like this:

https://www.yourappname.com/salesforce/callback?code=aWekysIEeqM9PiThEfm0Cnr6MoLIfwWyRJcqOqHdF8f9INokharAS09ia7UNP6RiVScerfhc4w%3D%3D

Setup 3: Authentication with Connected App

• We can now create the callback() method to authenticate onto our connected app. This method accepts the parameter code.

Note: Salesforce requires us to use FormUrlEncodedContent or it will complain of a bad request.

HttpClient client = new HttpClient();
var response = new HttpResponseMessage();
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12 | SecurityProtocolType.Ssl3;
var content = new FormUrlEncodedContent(new Dictionary<string, string>
{
    {"grant_type", "authorization_code "},
    {"client_id", YOUR_CONSUMER_Id}, //We will recevied from connected app
    {"client_secret", YOUR_CONSUMER_SECRET}, //We will recevied from connected app
    { "redirect_uri", YOUR_WEBAPP_URL+"/SalesforceCallBack"}, //Callback URL
    {"code",Code } //We will recevied while calling the Authorization
});
response = client.PostAsync(Url, content).Result;
string jsonResponse = response.Content.ReadAsStringAsync().Result;
var values = JsonConvert.DeserializeObject<Dictionary<string, string>>(jsonResponse);
AuthToken = values["access_token"];
InstanceUrl = values["instance_url"];

Let’s see an example request:

login.salesforce.com/services/oauth2/token?grant_type=authorization_code&redirect_uri=https://www.yourappname.com/salesforce/callback&client_id=YOUR_CONSUMER_ID&client_secret=YOUR_CONSUMER_SECRET&code=aWekysIEeqM9PiThEfm0Cnr6MoLIfwWyRJcqOqHdF8f9INokharAS09ia7UNP6RiVScerfhc4w%3D%3D

The response to our authentication request a JSON object containing the authentication token and the instance URL (where to direct all subsequent queries). We store these in the properties created above.

 Response: {
  "access_token" : "00D2v000001h1le!ARcAQDI9sqDLgzHr4zSZDzltr...",
  "instance_url" : "https://varianceinfotech.salesforce.com",
  "id" : "https://login.salesforce.com/id/00D2v000001h1le7EAE/005...",
  "token_type" : "Bearer",
  "issued_at" : "1569926610464",
  "signature" : "TmoeKs2s70SgVNxQSay..."
}

Refersh token example call:

https://login.salesforce.com/services/oauth2/token?grant_type=refresh_token&client_id=YOUR_CONSUMER__ID&client_secret=YOUR_CONSUMER__SECRET&refresh_token=YOUR_REFRESH_TOKEN

That’s it :-) We have authenticate our Salesforce App with .Net web project.
Cheers!

Conclusion

We’ve seen that calling the REST API from .Net is quite easy, especially with the help of the HttpClient class. The main challenges are around authenticating with Salesforce, the complexities of OAuth and the concept of the connected app.

Useful Resources

• Salesforce REST API
• Consuming Force.com Web Services with .Net
• The authoritative source for OAuth protocol is this RFC. It full of information but a bit of a dry read.