Having a problem getting a salesforce access token. I've got a post man call that works fun, but it's not working in code

Question

Having a problem getting a salesforce access token. Getting the access token works fine in postman, but what I'm trying to do it in C# i'm getting an error.

I've tried to doing the equivlent to what I was doing in postman but I'm not sure if getting this right.

var client = new HttpClient();
string baseAddress = @"https://test.salesforce.com/services/oauth2/token";

string grant_type = "authorization_code";
string client_id = "client_id here";
string client_secret = "client_secret here";
string auth_url = "https://test.salesforce.com/services/oauth2/authorize";
string callback_url = "https://app.getpostman.com/oauth2/callback";
string redirect_uri = "https://app.getpostman.com/oauth2/callback";

var form = new Dictionary<string, string>
{
    {"grant_type", grant_type},
    {"client_id", client_id},
    {"client_secret", client_secret},
    {"auth_url", auth_url},
    {"callback_url", callback_url},
    {"redirect_uri", redirect_uri}
};

HttpResponseMessage tokenResponse =  client.PostAsync(baseAddress, new FormUrlEncodedContent(form)).GetAwaiter().GetResult();
var jsonContent =  tokenResponse.Content.ReadAsStringAsync().GetAwaiter().GetResult();

This is the error I'm getting:

{ "error": "invalid_grant", "error_description":"invalid authorization code" }

Answer 1

The authorization code grant type (flow) in oAuth is a 2-step process:

1. Obtain authorization code (endpoint in Salesforce: /services/oauth2/authorize )
2. Exchange authorization code for access token (endpoint in Salesforce: /services/oauth2/token )

You seem to be doing step 2 without step 1. If you did perform step 1, you would have the authorization code...which must be included in step 2 as code parameter.

See Salesforce docs for examples and more details

Answer 2

You missed this additional paramerter called code

{ "grant_type", grant_type }, { "Code", authorizationcode }, { "client_id", client_id }, { "client_secret", client_secret }, { "auth_url", auth_url }, { "callback_url", callback_url }, { "redirect_uri", redirect_uri }