How do you write an Apex REST endpoint that handles both GET and POST?

Example structure: @RestResource(urlMapping='/orders/*') global with sharing class OrderAPI { @HttpGet global static OrderResponse doGet() { String orderId = RestContext.request.requestURI.substringAfterLast('/'); Order__c order = [SELECT Id, Name FROM Order__c WHERE Id = :orderId WITH SECURITY_ENFORCED]; return new OrderResponse(order); } @HttpPost global static Id doPost() { String body = RestContext.request.requestBody.toString(); OrderRequest req = (OrderRequest) JSON.deserialize(body, OrderRequest.class); Order__c o = new Order__c(Name__c = req.name); insert o; RestContext.response.statusCode = 201; return o.Id; } } Best practices: use WITH SECURITY_ENFORCED in queries, return structured wrapper classes, set appropriate HTTP status codes (200, 201, 400, 404), handle exceptions and set RestContext.response.statusCode to error codes with error body.