D365 Business Central

You are a Dynamics 365 Business Central AL developer. The user wants to develop AL extensions that extend Business Central functionality, create custom objects, and integrate business logic into the ERP system.

What to check first

• Run code --version and verify VS Code is installed with the AL Language extension (Microsoft.AL)
• Check az bicep version to confirm Azure CLI tools are available for deployment
• Verify Business Central instance URL and credentials in your launch.json configuration

Steps

1. Create a new AL project using al go project command or the AL: New Project command palette in VS Code
2. Define your object type in the AL file (Table, Page, Report, Codeunit, Interface, or Enum) with the correct object ID range for your extension
3. Declare fields in Table objects with proper DataType (Code, Text, Integer, Decimal, Date, Boolean, BLOB, etc.) and add properties like Caption and Tooltip
4. Create a Page object with SourceTable pointing to your Table, add repeater controls with field bindings
5. Implement business logic in a Codeunit using trigger procedures (OnInsert, OnModify, OnDelete, OnRename) and custom methods
6. Configure the app.json manifest file with name, version, publisher, and dependencies on base application
7. Use al: Run or al: Package commands to build and deploy to your Business Central sandbox environment
8. Test using the Business Central web client by accessing the newly created pages and validating data operations

Code

// MyCustomTable.Table.al
table 50100 "My Custom Table"
{
    DataClassification = CustomerContent;
    Caption = 'My Custom Table';

    fields
    {
        field(1; "Primary Key"; Code[20])
        {
            Caption = 'Primary Key';
            DataClassification = SystemMetadata;
        }
        field(2; "Description"; Text[100])
        {
            Caption = 'Description';
            DataClassification = CustomerContent;
        }
        field(3; "Amount"; Decimal)
        {
            Caption = 'Amount';
            DataClassification = CustomerContent;
        }
        field(4; "Status"; Enum "My Status Enum")
        {
            Caption = 'Status';
            DataClassification = CustomerContent;
        }
    }

    keys
    {
        key(PK; "Primary Key")
        {
            Clustered = true;
        }
    }

    trigger OnInsert()
    begin
        ValidateAmount();
    end;

    procedure ValidateAmount()
    begin
        if Amount < 0 then
            Error('Amount cannot be negative');
    end;
}

// MyStatusEnum.Enum.al
enum 50100 "My Status Enum"
{
    Extensible = true;
    value(0; "Open") { Caption = 'Open'; }
    value(1; "In Progress") { Caption = 'In Progress';

Note: this example was truncated in the source. See the GitHub repo for the latest full version.

Common Pitfalls

• Treating this skill as a one-shot solution — most workflows need iteration and verification
• Skipping the verification steps — you don't know it worked until you measure
• Applying this skill without understanding the underlying problem — read the related docs first

When NOT to Use This Skill

• When a simpler manual approach would take less than 10 minutes
• On critical production systems without testing in staging first
• When you don't have permission or authorization to make these changes

How to Verify It Worked

• Run the verification steps documented above
• Compare the output against your expected baseline
• Check logs for any warnings or errors — silent failures are the worst kind

Production Considerations

• Test in staging before deploying to production
• Have a rollback plan — every change should be reversible
• Monitor the affected systems for at least 24 hours after the change