How to Make Callouts from Salesforce: Apex and Declarative Methods

Salesforce provides multiple ways to make HTTP callouts to external services, both using Apex code and declarative tools like External Services and Named Credentials. This tutorial will cover both methods in detail, with examples to help you implement them.

1. Making Callouts Using Apex

Step 1: Create an Apex Class

To make an HTTP callout in Apex, you need to create an Apex class that performs the callout. Here’s a simple example of making a GET request to a public API that retrieves user data.

public class UserApiCallout {
    
    // Method to perform the callout
    @Future(callout=true)
    public static void getUserData() {
        try {
            // Create a new HTTP request
            HttpRequest req = new HttpRequest();
            req.setEndpoint('https://jsonplaceholder.typicode.com/users/1');
            req.setMethod('GET');

            // Create an HTTP object to send the request
            Http http = new Http();
            // Send the request and receive the response
            HttpResponse res = http.send(req);

            // Handle the response
            if (res.getStatusCode() == 200) {
                // Process the response, e.g., parse the JSON response
                String responseBody = res.getBody();
                System.debug('Response: ' + responseBody);
            } else {
                System.debug('Error: ' + res.getStatus());
            }
        } catch (Exception e) {
            System.debug('Exception: ' + e.getMessage());
        }
    }
}

Step 2: Call the Method

You can trigger the above method from a trigger, Visualforce page, or Lightning Component. For example, you could call it from an anonymous block of Apex code:

UserApiCallout.getUserData();

Step 3: Handle Authentication

If the API requires authentication (e.g., OAuth), you need to include the necessary headers in your request. Here’s an example with a Bearer token:

req.setHeader('Authorization', 'Bearer ' + yourAccessToken);

Step 4: Handle JSON Response

You can parse JSON responses using the JSON class in Apex. For example, to parse a JSON response into a custom Apex object:

public class User {
    public String name;
    public String email;
}

User user = (User)JSON.deserialize(res.getBody(), User.class);
System.debug('User Name: ' + user.name);
System.debug('User Email: ' + user.email);

2. Making Callouts Using Declarative Tools

Step 1: Using Named Credentials

Named Credentials simplify callouts by handling authentication and endpoint details declaratively.

1. Create a Named Credential:
   • Go to Setup > Named Credentials > New Named Credential.
   • Enter the required information:
     • Label: My API Credential
     • Name: My_APICredential
     • URL: https://jsonplaceholder.typicode.com
     • Authentication Protocol: Select the appropriate one (e.g., Password Authentication, OAuth 2.0).
   • Save the Named Credential.
2. Modify the Apex Code to Use Named Credential:

public class UserApiCallout {
    
    @Future(callout=true)
    public static void getUserData() {
        try {
            HttpRequest req = new HttpRequest();
            req.setEndpoint('callout:My_APICredential/users/1');
            req.setMethod('GET');

            Http http = new Http();
            HttpResponse res = http.send(req);

            if (res.getStatusCode() == 200) {
                String responseBody = res.getBody();
                System.debug('Response: ' + responseBody);
            } else {
                System.debug('Error: ' + res.getStatus());
            }
        } catch (Exception e) {
            System.debug('Exception: ' + e.getMessage());
        }
    }
}