Skills
skills/forcedotcom/afv-library/generating-apex

generating-apex

Installation
SKILL.md

Generating Apex

Use this skill for production-grade Apex: new classes, selectors, services, async jobs, invocable methods, and triggers; and for evidence-based review of existing .cls OR .trigger.

Required Inputs

Gather or infer before authoring:

  • Class type (service, selector, domain, batch, queueable, schedulable, invocable, trigger, trigger action, DTO, utility, interface, abstract, exception, REST resource)
  • Target object(s) and business goal
  • Class name (derive using the naming table below)
  • Net-new vs refactor/fix; any org/API constraints
  • Deployment targets (default to runSpecifiedTests and use generated tests where applicable)

Defaults unless specified:

  • Sharing: with sharing (see sharing rules per type below)
  • Access: public (use global only when required by managed packages or @RestResource)
  • API version: 66.0 (minimum version)
  • ApexDoc comments: yes

If the user provides a clear, complete request, generate immediately without unnecessary back-and-forth.

Workflow

All steps are sequential. Do not skip, merge, or reorder. If blocked, stop and ask for missing context. If not applicable, mark N/A with a one-line justification in the report.

Phase 1 — Author

  1. Discover project conventions

    • Service-Selector-Domain layering, logging utilities
    • Existing classes/triggers and current trigger framework or handler pattern
    • Whether Trigger Actions Framework (TAF) is already in use

  2. Choose the smallest correct pattern (see Type-Specific Guidance below)

  3. Review templates and assets

    • Read the matching template from assets/ before authoring (see Type-Specific Guidance for the file mapping)
    • When a references/ example exists for the type, read it as a concrete style guide
    • For any test class work, always read and use generating-apex-test skill

  4. Author with guardrails -- apply every rule in the Rules section below

    • Generate {ClassName}.cls with ApexDoc
    • Generate {ClassName}.cls-meta.xml

  5. Generate test classes -- Load the skill generating-apex-test to create {ClassName}Test.cls and {ClassName}Test.cls-meta.xml. Apex tests are always required to be generated to deploy. No test file creation or edits can occur without loading the generating-apex-test skill to generate tests.

Phase 2 — Validate (required before reporting)

Writing files is the midpoint, not the finish line. Steps 6 and 7 each require a tool invocation and produce output that must appear in the Step 8 report. Do not summarize or present the report until both steps have run and their output is captured.

  1. Run code analyzer

    • Invoke MCP run_code_analyzer on all generated/updated .cls files.
    • Remediate all sev0, sev1, and sev2 violations; re-run until clean.
    • Capture the final tool output verbatim for the report.
    • Fallback: sf code-analyzer run --target <target>. If both are unavailable, record run_code_analyzer=unavailable: <error> in the report.

  2. Execute Apex tests

    • Run org tests including {ClassName}Test via sf apex run test or MCP.
    • Delegate all test generation/fixes/coverage work to generating-apex-test; iterate until the tests pass.
    • Capture pass/fail counts and coverage percentage for the report.
    • If unavailable, record test_execution=unavailable: <error> in the report.

Phase 3 — Report

  1. Report -- use the output format at the bottom of this file.
    • The Analyzer line must contain the actual Step 6 tool output (or run_code_analyzer=unavailable: <reason> after attempting invocation).
    • The Testing line must contain the actual Step 7 results (or test_execution=unavailable: <reason> after attempting invocation).
    • A report missing either line is incomplete. Always attempt the tool invocation before recording unavailable.

Rules

Hard-Stop Constraints (Must Enforce)

If any constraint would be violated in generated code, stop and explain the problem before proceeding:

Constraint Rationale
Place all SOQL outside loops Avoid query governor limits (100 queries)
Place all DML outside loops Avoid DML governor limits (150 statements)
Declare a sharing keyword on every class Prevent unintended without sharing defaults and data exposure
Use Custom Metadata/Labels/describe calls instead of hardcoded IDs Ensure portability across orgs
Always handle exceptions (log, rethrow, or recover) Prevent silent failures
Use bind variables for all dynamic SOQL with user input Prevent SOQL injection
Use Apex-native collections (List, Map, Set) rather than Java types Prevent compile errors
Verify methods exist in Apex before use Prevent reliance on non-existent APIs
Avoid System.debug() in main code paths Debug statements evaluate even when loggign is not active and consume CPU. Use a logging framework if required on main code paths
Never use @future methods Use Queueable with System.Finalizer; @future cannot chain, cannot be called from Batch, and cannot accept non-primitive types

Bulkification & Governor Limits

  • All public APIs accept and process collections; single-record overloads delegate to the bulk method
  • In batch/bulk flows, prefer partial-success DML (Database.update(records, false)) and process SaveResult for errors
  • Use Map<Id, SObject> constructor for efficient ID-based lookups from query results
  • Use Map<Id, List<SObject>> to group child records by parent; build the map in a single loop before processing
  • Use Set<Id> for deduplication and membership checks; prefer Set.contains() over List.contains()
  • Use relationship subqueries to fetch parent + child records in a single SOQL when both are needed
  • Use AggregateResult with GROUP BY for rollup calculations instead of querying and counting in Apex
  • Only DML records that actually changed — compare against Trigger.oldMap or prior state before adding to the update list
  • Use Limits.getQueries(), Limits.getDmlStatements(), Limits.getCpuTime() to monitor consumption in complex transactions

SOQL Optimization

  • Use selective queries with proper WHERE clauses; use indexed fields (Id, Name, OwnerId, lookup/master-detail fields, ExternalId fields, custom indexes) in filters when possible
  • SELECT * does not exist in SOQL -- always specify the exact fields needed
  • Apply LIMIT clauses to bound result sets; use ORDER BY for deterministic results
  • When querying Custom Metadata Types (objects ending with __mdt), do NOT use SOQL — use the built-in methods ({CustomMdt__mdt}.getAll().values(), getInstance(), etc.)

Caching

  • Use Platform Cache (Cache.Org / Cache.Session) for frequently accessed, rarely changed data; set a TTL and always handle cache misses — cache can be evicted at any time
  • Use private static Map fields as transaction-scoped caches to prevent duplicate queries within the same execution context; lazy-initialize on first access

Security

  • Default to with sharing; document justification for without sharing or inherited sharing
  • WITH USER_MODE in SOQL and AccessLevel.USER_MODE for Database DML for CRUD/FLS enforcement
  • Validate dynamic field/operator names via allowlist or Schema.describe
  • Named Credentials for all external credentials/API keys
  • AuraHandledException for @AuraEnabled user-facing errors (no internal details)
  • without sharing requires a Custom Permission check
  • Isolate without sharing logic in dedicated helper classes; call from with sharing entry points to limit elevated-access scope
  • Encrypt PII/sensitive data at rest via Platform Encryption; never expose PII in debug statements, error messages, or API responses

Security Verification

Before finalizing, verify: CRUD/FLS enforced (SOQL + DML) · explicit sharing keyword on every class · no hardcoded secrets or Record IDs · PII excluded from logs and error messages · error messages sanitized for end users.

Error Handling

  • Catch specific exceptions before generic Exception; include context in messages
  • Use try/catch only around code that can throw (DML, callouts, JSON parsing, casts); avoid defensive wrapping of simple assignments/collection ops/arithmetic
  • Preserve exception cause chains: new CustomException('message', cause) (do not replace stack trace with concatenated messages)
  • Provide a custom exception class per service domain when meaningful
  • In @AuraEnabled methods, catch exceptions and rethrow as AuraHandledException
  • Fallback option: when no meaningful domain exception exists, catch generic Exception and either rethrow it or wrap it in a minimal custom exception that preserves the original cause.

Null Safety

  • Add guard clauses for null/empty inputs at the top of every public method; match style to context: return early in private/trigger-handler methods, throw exceptions in public APIs, record.addError() in validation services
  • Return empty collections instead of null
  • Use safe navigation (?.) for chained property access
  • Never dereference map.get(key) inline unless presence is guaranteed; use containsKey, assignment+null check, or safe navigation first
  • Use null coalescing (??) for default values
  • Prefer String.isBlank(value) over manual checks like value == null || value.trim().isEmpty()

Constants & Literals

  • Use enums over string constants whenever possible; enum values follow UPPER_SNAKE_CASE
  • Extract repeated literal strings/numbers into private static final constants or a constants class
  • Use Label. custom labels for user-facing strings
  • Use Custom Metadata for configurable values (thresholds, mappings, feature flags)
  • Never output HTML-escaped entities in code (e.g., &#39;); use literal single quotes ' in Apex string literals

Naming Conventions

Type Pattern Example
Service {SObject}Service AccountService
Selector {SObject}Selector AccountSelector
Domain {SObject}Domain OpportunityDomain
Batch {Descriptive}Batch AccountDeduplicationBatch
Queueable {Descriptive}Queueable ExternalSyncQueueable
Schedulable {Descriptive}Schedulable DailyCleanupSchedulable
DTO {Descriptive}DTO AccountMergeRequestDTO
Wrapper {Descriptive}Wrapper OpportunityLineWrapper
Utility {Descriptive}Util StringUtil
Interface I{Descriptive} INotificationService
Abstract Abstract{Descriptive} AbstractIntegrationService
Exception {Descriptive}Exception AccountServiceException
REST Resource {SObject}RestResource AccountRestResource
Trigger {SObject}Trigger AccountTrigger
Trigger Action TA_{SObject}_{Action} TA_Account_SetDefaults

Additional naming rules:

  • Classes: PascalCase
  • Methods: camelCase, start with a verb (get, create, process, validate, is, has, can)
  • Variables: camelCase, descriptive nouns; Lists as plural nouns (e.g., accounts, relatedContacts); Maps as {value}By{key} (e.g., accountsById); Sets as {noun}Ids
  • Constants: UPPER_SNAKE_CASE
  • Use full descriptive names instead of abbreviations (acc, tks, rec)

ApexDoc

  • Required on the class header and every public/global method
  • Include: brief description, @param, @return, @throws, @example where helpful

Class-level format:

/**
 * Provides services for geolocation and address conversion.
 */
public with sharing class GeolocationService { }

Method-level format:

/**
 * @param paramName Description of the parameter
 * @return Description of the return value
 * @example
 * List<Account> results = AccountService.deduplicateAccounts(accountIds);
 */

Code Structure & Architecture

  • Single responsibility per class; max 500 lines -- split when exceeded
  • Return Early: validate preconditions at method top, return/throw immediately
  • Extract private helpers for methods over ~40 lines
  • Use Dependency Injection (constructor/method params) for testability
  • Prefer composition and narrow interfaces over deep inheritance; extend via new implementations, not modifications
  • Enforce single-level abstraction per method across layer boundaries:
Layer Owns Must NOT contain
Trigger Event routing only Business logic, orchestration
Handler/Service Flow control, coordination Inline SOQL/DML/HTTP/parsing
Domain Business rules, validation Queries, callouts, persistence details
Data/Integration SOQL, DML, HTTP Business decisions
  • Disallowed: methods mixing orchestration with inline SOQL/DML/HTTP; business rules mixed with parsing internals; validation + persistence + cross-system plumbing in one method

Async Decision Matrix

Scenario Default Key Traits
Standard async work Queueable Job ID, chaining, non-primitive types, configurable delay (up to 10 min via AsyncOptions), dedup signatures
Very large datasets Batch Apex Chunked processing, max 5 concurrent; use QueryLocator for large scopes
Modern batch alternative CursorStep (Database.Cursor) 2000-record chunks, higher throughput, no 5-job limit
Recurring schedule Scheduled Flow (preferred) or Schedulable Schedulable has 100-job limit; use only when chaining to Batch or needing complex Apex logic
Post-job cleanup Finalizer (System.Finalizer) Runs regardless of Queueable success/failure
Long-running callouts Continuation Up to 3 per transaction, 3 parallel
Delays > 10 minutes System.scheduleBatch() Schedule a Batch job at a specific future time
Legacy fire-and-forget @future Do not use in new code — see Hard-Stop Constraints; replace with Queueable + Finalizer

Type-Specific Guidance

Service

  • Template: assets/service.cls · Reference: references/AccountService.cls
  • with sharing; stateless — no public fields or mutable instance state; keep public APIs focused and static where reasonable
  • Delegate all SOQL to Selectors and SObject behavior to Domains
  • Wrap business errors in a custom exception (e.g., AccountServiceException)

Selector

  • Template: assets/selector.cls · Reference: references/AccountSelector.cls
  • inherited sharing; one per SObject or query domain
  • Return List<SObject> or Map<Id, SObject>; use a shared base field list constant (no inline duplication)
  • Accept filter parameters; always include WITH USER_MODE

Domain

  • Template: assets/domain.cls
  • with sharing; encapsulate field defaults, derivations, and validations
  • Operate on in-memory lists only; no SOQL/DML (belongs in Services/Selectors)

Batch

  • Template: assets/batch.cls · Reference: references/AccountDeduplicationBatch.cls
  • with sharing; implement Database.Batchable<SObject> (add Database.Stateful when tracking across chunks)
  • start() = query definition; execute() = business logic; finish() = logging/notification
  • Use QueryLocator for large datasets; handle partial failures via Database.SaveResult
  • Accept filter parameters via constructor for reusability

Queueable

  • Template: assets/queueable.cls
  • with sharing; implement Queueable and optionally Database.AllowsCallouts when HTTP callouts are needed
  • Accept data via constructor
  • Add chain-depth guards to prevent infinite chains
  • Optionally implement Finalizer for recovery/cleanup
  • Use AsyncOptions for configurable delay (up to 10 min) and dedup signatures

Schedulable

  • Template: assets/schedulable.cls
  • with sharing; execute() delegates to Queueable or Batch
  • Provide CRON constants and a convenience scheduleDaily() helper

DTO / Wrapper

  • Template: assets/dto.cls
  • No sharing keyword needed (pure data containers)
  • Simple public properties; no-arg + parameterized constructors; Comparable when ordering matters
  • Use @JsonAccess on private/protected inner DTOs that are serialized/deserialized

Utility

  • Template: assets/utility.cls
  • No sharing keyword needed; all methods public static; private constructor
  • Pure, side-effect-free; no SOQL/DML

Interface

  • Template: assets/interface.cls
  • Define clear contracts with ApexDoc on each method signature

Abstract

  • Template: assets/abstract.cls
  • with sharing; offer default behavior via virtual methods
  • Mark extension points protected virtual or protected abstract
  • Include a concrete example in the ApexDoc showing how to extend the class

Custom Exception

  • Template: assets/exception.cls
  • No sharing keyword; extend Exception with descriptive names
  • Supported constructors: (), ('msg'), (cause), ('msg', cause)

Trigger

  • Template: assets/trigger.cls
  • One trigger per object; delegate all logic to handler/TAF action classes
  • Include all relevant DML contexts; if TAF: new MetadataTriggerHandler().run();

Trigger Action (TAF)

  • One class per concern per context; implement TriggerAction.{Context}
  • Register via Trigger_Action__mdt (actions are inactive without registration)
  • Name: TA_{SObject}_{ActionName}; prefer field-value comparison over static booleans for recursion

Invocable Method (@InvocableMethod)

  • Template: assets/invocable.cls
  • with sharing; inner Request/Response with @InvocableVariable
  • Method must be public static; non-static or single-object signatures will not compile
  • Accept List<Request>, return List<Response>; bulkify (SOQL/DML outside loops)
  • Decorator parameters: label (required — Flow Builder display name), description, category (groups actions in Builder), callout=true (required when method makes HTTP callouts)
  • @InvocableVariable parameters: label (required), description, required=true/false
  • @InvocableVariable supports: primitives, Id, SObject, List<T> only (no Map/Set/Blob); use List<Id> or List<SObject> fields for Flow collection I/O
  • Always include isSuccess, errorMessage, and errorType (e.getTypeName()) in Response
  • Return errors in Response (recommended); throwing an exception triggers the Flow Fault path — reserve for unrecoverable failures only

REST Resource (@RestResource)

  • Template: assets/rest-resource.cls
  • global with sharing; both class and methods must be global
  • Versioned URL: @RestResource(urlMapping='/{resource}/v1/*')
  • Use proper HTTP status codes per branch (200/201/400/404/422/500); never default all errors to 500
  • Validate inputs (Id format: Pattern.matches('[a-zA-Z0-9]{15,18}', value)); bind all user input in SOQL
  • Include LIMIT/ORDER BY in queries; implement pagination (pageSize/offset)
  • Standardized ApiResponse wrapper (success, message, data/records); inner request/response DTOs
  • Thin controller: delegate business logic to Service classes

@AuraEnabled Controller

  • with sharing; use WITH USER_MODE in all SOQL
  • Use @AuraEnabled(cacheable=true) only for read-only queries; leave cacheable unset for DML operations
  • Catch exceptions and rethrow as AuraHandledException with user-friendly messages

Output Expectations

Deliverables per class:

  • {ClassName}.cls
  • {ClassName}.cls-meta.xml (default API version 66.0 or higher unless specified)
  • {ClassName}Test.cls (generated via generating-apex-test skill)
  • {ClassName}Test.cls-meta.xml (generated via generating-apex-test skill)

Deliverables per trigger:

  • {TriggerName}.trigger
  • {TriggerName}.trigger-meta.xml (default API version 66.0 or higher unless specified)

Meta XML template:

<?xml version="1.0" encoding="UTF-8"?>
<ApexClass xmlns="http://soap.sforce.com/2006/04/metadata">
    <apiVersion>{API_VERSION}</apiVersion>
    <status>Active</status>
</ApexClass>

Report in this order:

Apex work: <summary>
Files: <paths>
Design: <pattern / framework choices>
Workflow: all steps completed (1-8); any N/A justified
Risks: <security, bulkification, async, dependency notes>
Analyzer: <REQUIRED -- paste actual run_code_analyzer output or state "run_code_analyzer=unavailable: <reason>">
Testing: <REQUIRED -- paste actual test execution results (pass/fail, coverage) or state "test_execution=unavailable: <reason>">
Deploy: <dry-run or next step>

Cross-Skill Integration

Need Delegate to
Apex tests / fix failures generating-apex-test skill
Describe objects/fields metadata skill (if available)
Deploy to org deploy skill (if available)
Flow calling Apex Flow skill (if available)
LWC calling Apex LWC skill (if available)

Troubleshooting Boundary

This skill handles production .cls/.trigger/.apex issues only: compile/parse failures, deployment dependency errors, runtime governor-limit failures. For test execution, assertions, coverage, or sf apex run test failures, delegate to generating-apex-test.

Weekly Installs
239
Repository
forcedotcom/afv-library
GitHub Stars
191
First Seen
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