How to consume a salesforce REST service?

Question

I want to integrate two salesforce orgs using username-password flow. First I got access token, after that I'm trying to call another service which is located in the org. I'm getting following error.

{"error":"unsupported_grant_type","error_description":"grant type not supported"}

Apex Class:

 public class SalesforceAuthentication
{
    public SalesforceAuthentication()
    {
    }
    public static void authenticate()
    {
        string authUrl = 'https://login.salesforce.com/services/oauth2/token';
        HttpRequest req = new HttpRequest();   
        req.setEndpoint(authUrl);
        req.setMethod('POST');
        req.setBody('grant_type=password&client_id=3MVG9ZL1234567890vLyXYRmRUuYKSgFgQayclpZBWmbi7PQ2vWj1V8Xev.GfE0C9xyWMrTzONlj2GZ0ow6VK&client_secret=2150505966475551576&[email protected]&password=secret123456Xe5pXoMwIDn1IOIFZqQt');
        Http http = new Http();
        HttpResponse response = http.send(req);

        AuthWrapper aw = (AuthWrapper)JSON.deserialize(response.getBody(),AuthWrapper.class);
        system.debug('auth response..!'+aw);

        String serviceUrl = aw.instance_url+'/services/apexrest/Account/0012800000ro2xS';
        req = new HttpRequest();
        req.setEndpoint(authUrl);
        req.setMethod('GET');
        req.setHeader('Authorization','Bearer '+aw.access_token);
        req.setHeader('Content-Type','application/json');
        response = http.send(req);
        system.debug('server response..!'+response.getBody());
    }

    public class AuthWrapper
    {
        public string access_token;
        public string instance_url;
        public string id;
        public string issued_at;
        public string signature;
    }
}

I'm trying to invoke authenticate() method from devoloper console. but I'm getting this error:

"Unsupported_grant_type"

Please help me resolve it.

Answer 1

Make sure you encode your email address. The @ character should be encoded to %40.

The following works for me:

string clientId = '3MVG9ZL0ppGP5UNot.A.Real.Client.Id.BWmbi7PQ2vWj1V8Xev.GfE0C9xyWMrTzONlj2GZ0ow6VK';
string clientSecret = '1234567896475551576';
// @ will be encoded to %40
string username = EncodingUtil.urlEncode('[email protected]', 'UTF-8');
string password = 'secret';
string securityToken = 'AllSoASecret43AMrNgcM92d0C2';

HttpRequest request=new HttpRequest();
request.setEndPoint('https://login.salesforce.com/services/oauth2/token');
request.setMethod('POST');
String reqbody = 'grant_type=password&client_id='+clientId+'&client_secret='+clientSecret+'&username='+username+'&password='+password+securityToken;
request.setBody(reqbody);
Http p=new Http();
HttpResponse response=p.send(request);
System.debug(response.getBody());

If there are additional problems check the Login History page for any additional failure reasons.