HTTP Callouts: Http, HttpRequest, HttpResponse
By the end of this lesson, you'll be able to:
- Build an HttpRequest with a method, endpoint, headers, and body
- Send it with the Http class and read the HttpResponse
- Connect this directly to Module 31's HttpCalloutMock lesson
Prerequisites: "XML Basics in Apex"
Building the request
HttpRequest request = new HttpRequest();
request.setEndpoint('https://api.example.com/shipping-rates');
request.setMethod('GET');
request.setHeader('Content-Type', 'application/json');HttpRequest is built up piece by piece: setEndpoint (the URL), setMethod (GET, POST, PUT, DELETE), and setHeader for any metadata the external API requires — this is the object Module 31's mock classes ultimately received as their respond(request) parameter.
Sending it and reading the response
Http http = new Http();
HttpResponse response = http.send(request);
if (response.getStatusCode() == 200) {
Map<String, Object> parsed = (Map<String, Object>) JSON.deserializeUntyped(response.getBody());
Decimal rate = (Decimal) parsed.get('rate');
} else {
System.debug('Callout failed with status: ' + response.getStatusCode());
}http.send(request) actually makes the call, returning an HttpResponse — getStatusCode() (Lesson 6's 200/500 pattern from Module 31) and getBody() (Lesson 2's JSON.deserializeUntyped) are exactly the methods every mock's fabricated response provided during testing.
A POST request with a body
HttpRequest request = new HttpRequest();
request.setEndpoint('https://api.example.com/orders');
request.setMethod('POST');
request.setHeader('Content-Type', 'application/json');
Map<String, Object> orderData = new Map<String, Object>{'productId' => 'W123', 'quantity' => 2};
request.setBody(JSON.serialize(orderData));
HttpResponse response = new Http().send(request);setBody combined with Lesson 2's JSON.serialize is the complete pattern for sending data to an external API, not just reading from one — this is genuinely everything a real callout needs.
Exercise
Build and send a GET request to 'https://api.example.com/status' and debug the response status code.
Show hint
setEndpoint, setMethod('GET'), then http.send(request).
HTTP Callouts: Http, HttpRequest, HttpResponse Quiz
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Summary
This lesson makes a real HTTP callout end to end — the exact thing Module 31's HttpCalloutMock lesson tested, finally shown from the calling side.