alguidelines/content/docs/vibe-coding/al-code-style.md

---
title: "AL Code Style & Formatting Rules"
description: >
  AL Code structure, formatting, and folder organization guidelines for AL development
globs: ["*.al"]
alwaysApply: true
---

# AL Code Style & Formatting Rules

These rules ensure consistent code structure and organization across AL projects, making code more maintainable and AI-assistant friendly.

## Style guidelines for AL code
  - Always use camelCase for variable and function names.
  - Use PascalCase for object names (e.g., tables, pages, reports).
  - Maintain a consistent indentation style (2 spaces preferred).

## Commonly used methods and patterns
  - Temporary tables for performance optimization
  - Use of events for extensibility

## Rule 1: Consistent Indentation and Formatting

### Intent
Maintain consistent code formatting to improve readability and enable better AI understanding of code structure. Use 2-space indentation consistently throughout your project and maintain consistent formatting within functions and procedures.

### Examples

```al
// Good example
procedure CalculateDiscount(Amount: Decimal; DiscountPct: Decimal): Decimal
begin
  if DiscountPct > 0 then
    exit(Amount * DiscountPct / 100);
    
  exit(0);
end;
```

## Rule 2: Feature-Based Folder Organization

### Intent
Organize code by business features rather than object types to improve maintainability and logical grouping. Use feature-based organization with `src/feature/subfeature/` structure and place shared components in `Common` or `Shared` folders.

### Examples

```
// Good example - Feature-based organization
src/
├── NoSeries/
│   ├── NoSeries.Table.al
│   ├── NoSeries.Page.al
│   └── NoSeriesSetup.Codeunit.al
├── Sales/
│   ├── Invoice/
│   │   ├── SalesInvoice.Page.al
│   │   └── SalesInvoicePosting.Codeunit.al
│   └── Order/
│       └── SalesOrder.Page.al
└── Common/
    ├── Helpers/
    │   └── DateHelper.Codeunit.al
    └── Interfaces/
        └── IPostable.Interface.al
```

```
// Bad example (avoid object-type segregation)
src/
├── Tables/
│   ├── NoSeries.Table.al
│   └── SalesHeader.Table.al
├── Pages/
│   ├── NoSeries.Page.al
│   └── SalesInvoice.Page.al
└── Codeunits/
    ├── NoSeriesSetup.Codeunit.al
    └── SalesInvoicePosting.Codeunit.al
```

## Rule 3: Code Documentation and Comments

### Intent
Provide clear documentation for global functions using XML documentation comments. Code should be self-documenting through clear naming, but global functions in codeunits require proper documentation for API clarity.

### Examples

```al
// Good example - XML documentation for global functions
codeunit 50100 "Base64 Convert"
{
    /// <summary>
    /// Converts the value of the input string to its equivalent string representation that is encoded with base-64 digits.
    /// </summary>
    /// <param name="String">The string to convert.</param>
    /// <returns>The string representation, in base-64, of the input string.</returns>
    procedure ToBase64(String: Text): Text
    begin
        exit(Base64ConvertImpl.ToBase64(String));
    end;

    /// <summary>
    /// Validates discount percentage against business rules.
    /// </summary>
    /// <param name="DiscountPct">The discount percentage to validate.</param>
    procedure ValidateDiscountPercentage(DiscountPct: Decimal)
    begin
        if DiscountPct > 50 then
            Error('Discount cannot exceed 50% due to company policy');
            
        if DiscountPct < 0 then
            Error('Discount percentage cannot be negative');
    end;
}
```

```al
// Bad example (avoid inline comments for obvious operations)
procedure ValidateDiscountPercentage(DiscountPct: Decimal)
begin
  // Check if discount is greater than 50
  if DiscountPct > 50 then
    Error('Discount cannot exceed 50%');
    
  // Check if discount is less than 0
  if DiscountPct < 0 then
    Error('Discount percentage cannot be negative');
end;
```

## Rule 4: Modular and Reusable Code Structure

### Intent
Keep code modular and reusable to enhance maintainability and reduce duplication. Write small, focused procedures that do one thing well and use interfaces and patterns where appropriate.

### Examples

```al
// Good example - Modular approach
procedure PostDocument(var DocumentHeader: Record "Sales Header")
begin
  ValidateDocument(DocumentHeader);
  CalculateTotals(DocumentHeader);
  CreateLedgerEntries(DocumentHeader);
  UpdateStatus(DocumentHeader);
end;

local procedure ValidateDocument(var DocumentHeader: Record "Sales Header")
begin
  if DocumentHeader."No." = '' then
    Error('Document number cannot be empty');
end;

local procedure CalculateTotals(var DocumentHeader: Record "Sales Header")
begin
  DocumentHeader.CalcFields(Amount);
end;
```

```al
// Bad example (avoid monolithic procedures)
procedure PostDocument(var DocumentHeader: Record "Sales Header")
begin
  // All validation, calculation, and posting logic in one procedure
  // ... 200+ lines of mixed concerns
end;
```