Mastering AL: A Beginner’s Guide to Learning AL (Application Language) from Scratch

Mastering AL: A Beginner’s Guide to Learning AL (Application Language) from Scratch

Table of Contents

Are you ready to dive into the world of AL programming? Whether you’re a seasoned developer or a complete beginner, learning AL from scratch is your gateway to unlocking the full potential of Microsoft Dynamics 365 Business Central. In this beginner’s guide, we’ll take you from scratch to confidently writing AL code, building extensions, and transforming your business processes. AL is the language used to develop extensions for Business Central, and learning it opens up a world of possibilities for customizing and extending the platform’s functionality. By the end of this guide, you’ll have a solid foundation in AL and be ready to start building your own extensions. Let’s get started!

[Revamp] – Learning AL from Scratch: Modernize Your Development Skills

If you’re looking to modernize your development skills, mastering AL is the way to go. AL, or Application Language, is the programming language designed for creating extensions in Microsoft Dynamics 365 Business Central. Unlike its predecessor, C/AL, AL is built for the cloud and offers a streamlined approach to customizing Business Central. Whether you’re automating workflows, integrating with external systems, or adding custom features, AL is your tool of choice.

Why should you care about mastering AL? It’s the future of Business Central development. With the shift to cloud-based solutions, AL enables you to build extensions without altering the core system. This keeps upgrades smooth and reduces maintenance hassles. Plus, AL works seamlessly with Visual Studio Code (VS Code), a powerful editor that enhances your development experience.

Business Central AL interface showing an open project in VS Code. — The VS Code interface with an AL project open, ready for development.

Technical Insight: AL integrates with Business Central through the AL Language extension in VS Code. You write code that hooks into events and APIs, extending functionality without touching the base system. This event-driven model is central to modern Business Central development.

[Blueprint] – Setting Up Your AL Development Environment

Before you write a single line of AL code, you need a proper development environment. This involves installing VS Code, adding the AL Language extension, creating a new project, and connecting to a Business Central sandbox. Here’s how to do it.

Step 1: Install VS Code

VS Code is a free, open-source editor ideal for AL development. Download it from the official VS Code website. After installation, launch VS Code to proceed.

Step 2: Add the AL Language Extension

The AL Language extension powers AL development in VS Code. Here’s how to install it:

Open VS Code.
Click the Extensions icon in the sidebar or press Ctrl+Shift+X.
Search for “AL Language” and click “Install.”

Business Central AL interface showing the AL Language extension installation. — Installing the AL Language extension in VS Code.

Step 3: How to Create a New Project in VS Code

To start developing, you need to create a new AL project:

Press Ctrl+Shift+P to open the Command Palette.
Type “AL: Go!” and select it.
Choose a folder to save your project and name it (e.g., “HelloWorldExtension”).
VS Code will generate the necessary files, including app.json (defines your extension) and launch.json (configures your connection).

Business Central AL interface showing the creation of a new project in VS Code. — Creating a new AL project in VS Code using the ‘AL: Go!’ command.

Step 4: How to Set Up a Sandbox Environment in VS Code

A sandbox is a safe testing ground for your extensions. You can create one via the Business Central admin center or use a local Docker container. To connect VS Code to your sandbox:

Open the launch.json file in your project (found in the .vscode folder).
Update the “server” field with your sandbox URL (e.g., https://your-sandbox-url.com).
Set “serverInstance” to your instance name (e.g., BC).
Set “authentication” to “UserPassword” and provide your sandbox credentials under “user” and “password”.
Save the file.

Example: launch.json:

{
“version”: “0.2.0”,
“configurations”: [
{
“name”: “Your Sandbox”,
“server”: “https://your-sandbox-url.com”,
“serverInstance”: “BC”,
“authentication”: “UserPassword”,
“user”: “your-username”,
“password”: “your-password”,
“type”: “al”
}
]
}

Insight: A well-configured environment prevents errors and speeds up development. Test your connection by pressing F5 to ensure VS Code links to your sandbox.

[Breakdown] – Understanding AL Syntax and Structure

With your environment ready, let’s explore AL syntax and structure. AL is an object-oriented language tailored for business logic. Here are the essentials for mastering AL.

Variables and Data Types

Variables store data and require a defined type. Common types include:

Integer: Whole numbers (e.g., myNumber: Integer;).
Decimal: Precise numbers (e.g., price: Decimal;).
Text: Strings (e.g., message: Text;).
Boolean: True/false values (e.g., isActive: Boolean;).

Procedures and Functions

Procedures are reusable code blocks. They can accept parameters and return values. For example:

procedure CalculateDiscount(Price: Decimal; DiscountPercentage: Decimal): Decimal
begin
exit(Price * (1 – DiscountPercentage / 100));
end;

This calculates a discounted price based on input values.

Events

Events let you extend Business Central without modifying core code. You subscribe to triggers like record insertions. Example:

[EventSubscriber(ObjectType::Table, Database::Customer, ‘OnAfterInsertEvent’, ”, false, false)]
local procedure OnAfterCustomerInsert(var Rec: Record Customer)
begin
Message(‘New customer added!’);
end;

Business Central AL interface showing a code snippet in VS Code. — A sample AL code snippet showing variables and a procedure in VS Code.

Value Tip: Beginners often forget to declare variables or misuse data types. Double-check declarations to avoid errors.

[Spotlight] – Building Your First AL Extension

Now, let’s put your skills to work by building a simple “Hello World” extension. This will reinforce your path to mastering AL.

Step 1: Write the Code

In your project, create a file called HelloWorld.al with this code:

pageextension 50100 CustomerCardExtension extends “Customer Card”
{
layout
{
addafter(“Name”)
{
field(HelloWorld; ‘Hello, World!’)
{
ApplicationArea = All;
}
}
}
}

This adds a “Hello World!” field to the Customer Card page.

Step 2: Deploy and Test

Press F5 to deploy to your sandbox. Open Business Central, navigate to Sales > Customers, and open a Customer Card to see your message.

Business Central interface showing the Hello World extension. — The ‘Hello World!’ extension on the Customer Card in Business Central.

Call to Action: You’ve built your first extension! Keep going—try adding logic or integrating APIs next.

[Insight] – Integrating APIs in AL Extensions

To take your extensions further, you can integrate external APIs. Here’s how to find and use APIs in Business Central.

Finding API Endpoints in Business Central

Business Central exposes APIs for entities like customers, items, and sales orders. To access them:

In Business Central, search for Web Services in the top-right search bar.
Navigate to the Web Services page.
Look for APIs like customers or salesOrders in the list.
Highlight the OData V4 URL column—this is the endpoint you’ll use in VS Code (e.g., https://your-bc-url.com/api/v2.0/customers).

Business Central interface showing API endpoints in Web Services. — Accessing API endpoints in Business Central via Web Services.

Technical Tip: Use the HttpClient class in AL to call these APIs. Example:

procedure GetCustomerData()
var
Client: HttpClient;
Response: HttpResponseMessage;
Url: Text;
begin
Url := ‘https://your-bc-url.com/api/v2.0/customers’;
Client.Get(Url, Response);
if Response.IsSuccessStatusCode then
Message(‘API call successful!’)
else
Error(‘API call failed.’);
end;

Ensure you handle authentication (e.g., OAuth) and error responses properly.

Key Takeaways Table

#	Feature	Description
1	AL Language	Powers extension development in Business Central.
2	VS Code Integration	Enhances coding with tools like debugging.
3	Event-Driven Model	Extends functionality safely via events.
4	Sandbox Environment	Enables safe testing and development.
5	API Integration	Connects Business Central to external systems.

FAQ Section

1. How do I start learning AL from scratch?

Set up VS Code with the AL Language extension, create a new project, and connect to a sandbox. Follow tutorials like this guide to learn syntax and build extensions.

2. What are common mistakes when learning AL from scratch?

Beginners often misdeclare variables, misunderstand events, or skip environment setup. Verify your code and configuration to avoid these pitfalls.

3. How does AL improve Business Central development?

AL enables extension-based customization, keeping the core system intact. This ensures easier upgrades and cleaner code.

4. Can I integrate AL extensions with external tools?

Yes, AL supports APIs, letting you connect Business Central to tools like CRM or e-commerce platforms seamlessly.

5. How do I measure the impact of my AL extensions?

Track time saved, error reduction, and user feedback. Use Business Central reports to quantify efficiency gains.

Mastering AL takes practice, but this guide gives you the foundation to succeed. Experiment with code, explore Business Central documentation, and check our extension development guide for more. Happy coding!