How can I use the grant_type=password oauth flow with salesforce.com?

Question

I'm trying to get an authorization token using the Username-Password flow (as described in the final section of this article).

I'm sending the following request (using Python's httplib, in case that's relevant):

https://login.salesforce.com/services/oauth2/token

POST data:

username=<un>&client_secret=<consumer_secret>&password=<pw+token>&grant_type=password&client_id=<consumer_key>

And getting the response:

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

Is the password grant_type really unsupported, or am I missing something? It seems to give this error even when I'm sending a grant_type that definitely does work (such as authorization_code).

Note that I've tried the suggestions in the answer here, and they don't work for me.

Answer 1

Typically this is because the content-type header has not been set to the correct value, it should be application/x-www-form-urlencoded.

Also make sure your parameters are correctly encoded (especially if you're building the POST payload by hand).

Answer 2

Below is detailed function/logic on how to use grant_type=password oauth flow with salesforce.com in JAVA:

    // Authenticate via OAuth
    JSONObject response = oauthLogin();
    System.out.println("Login response: " + response.toString(2));
    if (!response.has("access_token")) {
        throw new Exception("OAuth failed: " + response.toString());
    }

    ..........................


    private static JSONObject oauthLogin() throws Exception {

    org.eclipse.jetty.client.HttpClient jettyHttpClient = new org.eclipse.jetty.client.HttpClient();
    jettyHttpClient.start();

    String url = LOGIN_SERVER + "/services/oauth2/token";

    ContentExchange exchange = new ContentExchange();
    exchange.setMethod("POST");
    exchange.setURL(url);

    String message = "grant_type=password&client_id=" + CLIENT_ID
            + "&client_secret=" + CLIENT_SECRET + "&username=" + USERNAME
            + "&password=" + PASSWORD;

    exchange.setRequestHeader("Content-Type",
            "application/x-www-form-urlencoded");
    exchange.setRequestContentSource(new ByteArrayInputStream(message
            .getBytes("UTF-8")));

    jettyHttpClient.send(exchange);
    exchange.waitForDone();

    return new JSONObject(new JSONTokener(exchange.getResponseContent()));
}