REST Resources in Apex (@RestResource)

Every earlier lesson in this module was Apex reaching out to an external system. @RestResource does the opposite: it exposes an Apex class as a REST API endpoint that external systems can call into Salesforce — genuinely the reverse integration direction.

@RestResource(urlMapping='/accounts/*')
global with sharing class AccountRestService {
    @HttpGet
    global static Account getAccount() {
        RestRequest req = RestContext.request;
        String accountId = req.requestURI.substring(req.requestURI.lastIndexOf('/') + 1);
        return [SELECT Id, Name, Industry FROM Account WHERE Id = :accountId];
    }
}

@RestResource(urlMapping='/accounts/*') names the URL path; @HttpGet marks this specific method as handling GET requests to that path. Note global — REST resource classes and their methods must be global, since they're callable from entirely outside the org, a stricter exposure than even @AuraEnabled's public.

@RestResource(urlMapping='/accounts/*')
global with sharing class AccountRestService {
    @HttpPost
    global static Id createAccount(String name, String industry) {
        Account acc = new Account(Name = name, Industry = industry);
        insert acc;
        return acc.Id;
    }
}

@HttpPost handles incoming POST requests — parameters here map automatically from the incoming request's JSON body (Lesson 2's JSON.deserialize concept, handled implicitly by the framework this time) onto the method's own parameters.