Salesforce Apex Quality

# Salesforce Apex Quality Guardrails

Apply these checks to every Apex class, trigger, and test file you write or review.

## Step 1 — Governor Limit Safety Check

Scan for these patterns before declaring any Apex file acceptable:

### SOQL and DML in Loops — Automatic Fail

```apex
// ❌ NEVER — causes LimitException at scale
for (Account a : accounts) {
    List<Contact> contacts = [SELECT Id FROM Contact WHERE AccountId = :a.Id]; // SOQL in loop
    update a; // DML in loop
}

// ✅ ALWAYS — collect, then query/update once
Set<Id> accountIds = new Map<Id, Account>(accounts).keySet();
Map<Id, List<Contact>> contactsByAccount = new Map<Id, List<Contact>>();
for (Contact c : [SELECT Id, AccountId FROM Contact WHERE AccountId IN :accountIds]) {
    if (!contactsByAccount.containsKey(c.AccountId)) {
        contactsByAccount.put(c.AccountId, new List<Contact>());
    }
    contactsByAccount.get(c.AccountId).add(c);
}
update accounts; // DML once, outside the loop
```

Rule: if you see `[SELECT` or `Database.query`, `insert`, `update`, `delete`, `upsert`, `merge` inside a `for` loop body — stop and refactor before proceeding.

## Step 2 — Sharing Model Verification

Every class must declare its sharing intent explicitly. Undeclared sharing inherits from the caller — unpredictable behaviour.

| Declaration | When to use |
|---|---|
| `public with sharing class Foo` | Default for all service, handler, selector, and controller classes |
| `public without sharing class Foo` | Only when the class must run elevated (e.g. system-level logging, trigger bypass). Requires a code comment explaining why. |
| `public inherited sharing class Foo` | Framework entry points that should respect the caller's sharing context |

If a class does not have one of these three declarations, **add it before writing anything else**.

## Step 3 — CRUD / FLS Enforcement

Apex code that reads or writes records on behalf of a user must verify object and field access. The platform does **not** enforce FLS or CRUD automatically in Apex.

```apex
// Check before querying a field
if (!Schema.sObjectType.Contact.fields.Email.isAccessible()) {
    throw new System.NoAccessException();
}

// Or use WITH USER_MODE in SOQL (API 56.0+)
List<Contact> contacts = [SELECT Id, Email FROM Contact WHERE AccountId = :accId WITH USER_MODE];

// Or use Database.query with AccessLevel
List<Contact> contacts = Database.query('SELECT Id, Email FROM Contact', AccessLevel.USER_MODE);
```

Rule: any Apex method callable from a UI component, REST endpoint, or `@InvocableMethod` **must** enforce CRUD/FLS. Internal service methods called only from trusted contexts may use `with sharing` instead.

## Step 4 — SOQL Injection Prevention

```apex
// ❌ NEVER — concatenates user input into SOQL string
String soql = 'SELECT Id FROM Account WHERE Name = \'' + userInput + '\'';

// ✅ ALWAYS — bind variable
String soql = [SELECT Id FROM Account WHERE Name = :userInput];

// ✅ For dynamic SOQL with user-controlled field names — validate against a whitelist
Set<String> allowedFields = new Set<String>{'Name', 'Industry', 'AnnualRevenue'};
if (!allowedFields.contains(userInput)) {
    throw new IllegalArgumentException('Field not permitted: ' + userInput);
}
```

## Step 5 — Modern Apex Idioms

Prefer current language features (API 62.0 / Winter '25+):

| Old pattern | Modern replacement |
|---|---|
| `if (obj != null) { x = obj.Field__c; }` | `x = obj?.Field__c;` |
| `x = (y != null) ? y : defaultVal;` | `x = y ?? def