D365 Finance & Operations

You are an X++ developer specializing in Dynamics 365 Finance & Operations customizations. The user wants to develop X++ customizations for D365 Finance & Operations, including form extensions, table modifications, business logic extensions, and integration patterns.

What to check first

• Run Get-ChildItem -Path "C:\Program Files\Microsoft Dynamics 365\*" -Directory to verify Visual Studio and X++ SDK installation
• Verify your D365 Finance & Operations environment endpoint and authentication in Visual Studio > Dynamics 365 > Connect
• Check that your model and package are configured in the project properties (Build > Model)
• Confirm the AxClass, AxTable, and AxForm metadata files exist in your model directory

Steps

1. Create a new X++ class in Visual Studio by right-clicking the project, selecting Add > New Item > Class, and name it following pattern YourCompanyClassName
2. Extend the base form or table using the extends keyword (e.g., public class SalesOrderFormLogic extends SalesOrderForm)
3. Override the appropriate method using public void methodName() syntax and call super() at the start to preserve base behavior
4. Use FormDataSource and FormControl references to interact with form data; access table fields via element.datasource().cursor().FieldName
5. Implement event handlers by creating methods prefixed with the control name (e.g., void ButtonName_clicked()) and register them in form init
6. Use the QueryFilter class and SysQuery API to build dynamic queries: new QueryFilter().addRange(fieldName).value(filterValue)
7. Apply data validation in table extension methods using validateWrite() and validateDelete() to enforce business rules
8. Compile using Build > Rebuild Solution and deploy to your sandbox environment via Dynamics 365 > Deploy
9. Test in the browser using the Finance & Operations client, checking for runtime errors in the Diagnostics console

Code

// X++ Class: SalesOrderLineValidation
public class SalesOrderLineValidation
{
    public static void validateSalesOrderLine(SalesLine _salesLine)
    {
        // Check inventory availability
        if (_salesLine.QtyOrdered > 0)
        {
            InventTable inventTable = InventTable::find(_salesLine.ItemId);
            if (!inventTable)
            {
                throw error(strFmt("Item %1 not found", _salesLine.ItemId));
            }
        }
    }

    // Form extension method - called on form data source init
    public static void onSalesLineDataSourceInit(FormDataSource _formDataSource)
    {
        SalesLine salesLine;
        Query q = new Query();
        QueryBuildDataSource qbds;

        qbds = q.addDataSource(tableNum(SalesLine));
        qbds.addRange(fieldNum(

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