Business Central API Page Generator

Generates production-ready AL API page objects following Microsoft's API v2.0 standards. Handles field mappings, navigation properties, custom actions, and permission sets.

Quick Start

page [ID] "[EntityName] API"
{
    APIVersion = 'v2.0';
    APIPublisher = '[publisher]';
    APIGroup = '[group]';

    EntityCaption = '[Entity Name]';
    EntitySetCaption = '[Entity Names]';
    EntityName = '[entityName]';       // camelCase, singular
    EntitySetName = '[entityNames]';   // camelCase, plural

    PageType = API;
    SourceTable = "[Source Table]";
    DelayedInsert = true;
    ODataKeyFields = SystemId;

    AboutText = 'API endpoint for [description]. Supports GET, POST, PATCH, DELETE operations.';
    Extensible = false;
}

Endpoint URL: /api/v2.0/companies({companyId})/[entityNames]

Prerequisites

• Source table with proper primary key
• Available page ID (Object ID Ninja or manual allocation)
• Clear list of fields to expose
• Permission requirements defined

API Page Properties

Layout Pattern

Fields follow this ordering in the repeater(Group):

layout
{
    area(Content)
    {
        repeater(Group)
        {
            // 1. System ID (always first, read-only)
            field(id; Rec.SystemId)
            {
                Caption = 'Id';
                Editable = false;
            }

            // 2. Business key fields (often read-only after creation)
            field(number; Rec."No.")
            {
                Caption = 'Number';
                Editable = false;
            }

            // 3. Required business fields
            field(customerNumber; Rec."Sell-to Customer No.")
            {
                Caption = 'Customer Number';
            }

            // 4. Optional business fields
            field(customerName; Rec."Sell-to Customer Name")
            {
                Caption = 'Customer Name';
                Editable = false;  // Calculated/FlowField
            }

            // 5. Calculated/summary fields (Editable = false)

            // 6. Status fields (Editable = false)

            // 7. Timestamp fields (always last)
            field(lastModifiedDateTime; Rec.SystemModifiedAt)
            {
                Caption = 'Last Modified Date Time';
                Editable = false;
            }

            // 8. Navigation properties (part/lines)
            part(salesOrderLines; "[EntityName] Lines API")
            {
                Caption = 'Lines';
                EntityName = '[entityName]Line';
                EntitySetName = '[entityName]Lines';
                SubPageLink = "Document Type" = field("Document Type"),
                              "Document No." = field("No.");
            }
        }
    }
}

Field rules:

• camelCase identifiers, clear descriptive captions
• Mark calculated/FlowFields and system fields as Editable = false
• Group related fields logically

Field Naming Conventions

Rules: camelCase consistently, remove spaces/special characters, follow REST/JSON conventions, use standard names for common concepts (id, number, description, status).

API Design Workflow

1. Define purpose — Who consumes this API? What operations? What data? Performance requirements?
2. Plan resource model — Identify entities, relationships, navigation properties, filtering needs
3. Allocate object IDs — API pages typically in 50100-50199; keep header/lines close (e.g., 50110, 50111)
4. Implement API page(s) — Start with header, add lines page if header-lines pattern, add validation triggers and actions
5. Create permission sets — Full access and read-only variants
6. Test API — Verify CRUD operations, actions, navigation properties, error responses

Checklist

Before completing API page generation:

• API properties defined (version, publisher, group, entity names)
• AboutText property added with clear description
• Source table has proper primary key
• Fields use camelCase naming
• System fields included (id, lastModifiedDateTime)
• Calculated fields marked Editable = false
• Navigation properties defined for related tables
• Validation triggers implemented
• Custom actions added if needed
• Permission sets created
• API tested with CRUD operations

References

For complete examples, patterns, and additional guidance:

• references/api-examples.md — Full working examples (simple page, header-lines pattern), action patterns, validation triggers, HTTP test templates
• references/api-patterns.md — Common patterns (read-only, calculated fields, enums), performance considerations, security/permissions templates, tips

External Resources

• Developing a Custom API — Microsoft Docs
• OData v4.0 Protocol — API standards
• OAuth 2.0 for Business Central — Authentication