Review and Refactor
By the end of this lesson, you'll be able to:
- Review the complete payment feature across every layer built this module
- Confirm every design decision from Lesson 1 was actually satisfied
- Apply the full course checklist to a genuinely high-stakes feature
Prerequisites: "Monitor Transactions"
The complete feature, layer by layer
OrderTriggerHandler (thin, enqueues only)
ProcessPaymentJob (Queueable, retry-aware, updates Order__c)
PaymentGatewayService (the actual callout, typed PaymentResult)Three classes, each with one job — the exact same shape as Module 26, Module 30, and Module 35's projects, now applied to genuinely the highest-stakes data this course has worked with.
Checking against Lesson 1's original design
- No synchronous callout in the trigger? Yes — the trigger only enqueues (Lesson 3).
- Three outcomes handled distinctly? Yes — success, decline, error each get their own status and logic (Lessons 2-4).
- Declines never retried? Yes, explicitly excluded from the retry branch (Lesson 4).
- Errors retried with a limit? Yes, capped at 3 attempts (Lesson 4).
- Raw card data never touches Salesforce? Yes — payment tokens only, throughout (Lesson 5).
- Every path tested, including the retry boundary? Yes (Lesson 6).
- Stuck transactions monitorable? Yes (Lesson 7).
What this project represents in the course
This closes out Part XVII by combining genuinely everything the course has built toward: triggers (24), bulkification (25), security (28), custom exceptions (22), testing (31), callouts (36), and asynchronous Apex (38) — all in service of one real, high-stakes feature. Only three modules remain before the course's final capstone, and they cover DevOps practices, architecture patterns, and platform-scale concepts that this project's structure has already been quietly preparing for.
Exercise
As a comment, name which single design decision from Lesson 1 you think mattered most to getting right, and why.
Show hint
Consider the consequences of getting each one wrong.
Review and Refactor Quiz
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Summary
The closing lesson reviews the entire payment gateway feature — trigger, Queueable job, service, security, tests, and monitoring — against everything this course has built toward.