Bad request while trying to get authToken using docusign API - docusignapi

Question

I am new to docuSign API and I followed the code sample for C# in DocuSign guide site. I failed at the step while I was trying to get AuthToken. Part of my code as below, basically the same as the DocuSign sample,
public void OAuthAuthorizationCodeFlowTest()
{
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
// Make an API call with the token
ApiClient apiClient = new ApiClient(RestApiUrl);
DocuSign.eSign.Client.Configuration.Default.ApiClient = apiClient;
// Initiate the browser session to the Authentication server
// so the user can login.
string accountServerAuthUrl =
apiClient.GetAuthorizationUri(client_id, redirect_uri, true,
stateOptional);
System.Diagnostics.Process.Start(accountServerAuthUrl);
string accessToken = apiClient.GetOAuthToken(client_id,
client_secret, true, AccessCode);
// login call is available in the authentication api
AuthenticationApi authApi = new AuthenticationApi();
LoginInformation loginInfo = authApi.Login();
// parse the first account ID that is returned (user might belong to
multiple accounts)
AccountId = loginInfo.LoginAccounts[0].AccountId;
BaseUri = loginInfo.LoginAccounts[0].BaseUrl;
Console.WriteLine("accountId: " + AccountId);
Console.WriteLine("base_uri: " + BaseUri);
The client_id is my integrator key, the client_secret is the secret key related to that integrator key, right? I checked them many times, no problem. I am confused now why am I still getting 400 error. Please shed me some light here, thanks!!!

Answer 1

System.Diagnostics.Process.Start(accountServerAuthUrl); will open it on a browser, and once you have done successful authentication then browser will be redirected with the query parameter code=.... in the callback url (redirect_uri)
The code in browser needs to be read by your WEBApp, and then you need to call below code to generate the AccessToken:
string accessToken = apiClient.GetOAuthToken(client_id,
client_secret, true, AccessCode);
Below code is one part, to open the browser, ideally it is for testing purpose on a Standalone system, on a WEBApp you will redirect the browser to accountServerAuthUrl
public void OAuthAuthorizationCodeFlowTest()
{
// Make an API call with the token
ApiClient apiClient = new ApiClient(RestApiUrl);
DocuSign.eSign.Client.Configuration.Default.ApiClient = apiClient;
// Initiate the browser session to the Authentication server
// so the user can login.
string accountServerAuthUrl = apiClient.GetAuthorizationUri(client_id, redirect_uri, true, stateOptional);
System.Diagnostics.Process.Start(accountServerAuthUrl);
}
Below code is run when user is authenticated by the DocuSign on the browser and browser is redirected to the redirect_uri with code=..., your Webapp will read this code and send it as AccessCode and will call below code from your controller,
string accessToken = apiClient.GetOAuthToken(client_id, client_secret, true, AccessCode);