HTTP POST Request from Salesforce Apex code to get access_token?

Question

I am new to Salesforce but aware about the REST. I'm trying to make the HTTP POST call to get the access_token first to call the actual GET, PUT and POST service.

I have written the following code in developer console and same will try in test class.

Http http = new Http();
HttpRequest request = new HttpRequest();
request.setEndpoint('https://ap5.salesforce.com/services/oauth2/token');
request.setMethod('POST');

request.setHeader('Content-Type', 'application/json;charset=UTF-8');
request.setHeader('client_id','3MVG9d8..z.hDcPJZPIzGJ5UZDrL7bJthAQ_v0YCxzEeG1XXXXXXXXXXXXXXXXXXXXX');
request.setHeader('client_secret','XXXXXXXXXXX');
request.setHeader('username','XXXXXXXXXXXXX.com');
request.setHeader('password','XXXXXXXXXXXXX');
request.setHeader('grant_type','password');

request.setBody('');

HttpResponse response = http.send(request);
System.debug('Response :: '+response.getBody());

I am not sure when if we need to send above data in header or body? But when I tried using header I get the following error. Please guide further.

Line: 15, Column: 1
System.CalloutException: Unauthorized endpoint, please check Setup->Security->Remote site settings. endpoint = https://ap5.salesforce.com/services/oauth2/token

When I tried in REST Client, it works fine.

Answer 1

The error message tells you exactly what you need to do. Before making any Http callout, you must first authorize the endpoint by adding it to your Remote Site Settings. Navigate to Setup > Security > Remote Site Settings, then add https://ap5.salesforce.com:

See also: Adding Remote Site Settings:

Before any Apex callout can call an external site, that site must be registered in the Remote Site Settings page, or the callout fails. Salesforce prevents calls to unauthorized network addresses.

Note
If the callout specifies a named credential as the endpoint, you don’t need to configure remote site settings. A named credential specifies the URL of a callout endpoint and its required authentication parameters in one definition. To set up named credentials, see “Define a Named Credential” in the Salesforce Help.

To add a remote site setting:

1. From Setup, enter Remote Site Settings in the Quick Find box, then select Remote Site Settings.
2. Click New Remote Site.
3. Enter a descriptive term for the Remote Site Name.
4. Enter the URL for the remote site.
5. Optionally, enter a description of the site.
6. Click Save.