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API Patterns & Best Practices

Common Patterns​

Read-Only API​

page 50120 "Customers API"
{
    // ... standard properties ...

    Editable = false;
    InsertAllowed = false;
    ModifyAllowed = false;
    DeleteAllowed = false;

    layout
    {
        area(Content)
        {
            repeater(Group)
            {
                // All fields automatically non-editable
            }
        }
    }
}

Calculated/Virtual Fields​

field(creditLimitExceeded; IsCreditLimitExceeded())
{
    Caption = 'Credit Limit Exceeded';
    Editable = false;
}

local procedure IsCreditLimitExceeded(): Boolean
begin
    exit(Rec."Balance (LCY)" > Rec."Credit Limit (LCY)");
end;

Enum/Option Fields​

field(status; Rec.Status)
{
    Caption = 'Status';
}

// API returns: "status": "open" or "status": "released"
// API accepts: { "status": "open" } or { "status": "released" }

Performance Considerations​

1. Support Filtering​

Ensure proper keys exist on source table:

table "Your Table"
{
    keys
    {
        key(PK; "No.") { Clustered = true; }
        key(Customer; "Customer No.", "Order Date") { }
        key(Status; Status, "Order Date") { }
    }
}

2. Use SetLoadFields​

trigger OnAfterGetRecord()
begin
    Rec.SetLoadFields("No.", "Description", "Unit Price");
end;

3. Limit FlowFields in API​

  • Avoid heavy FlowFields that require calculation
  • Mark complex FlowFields as Visible = false unless critical
  • Consider dedicated summary endpoints for aggregations

Security & Permissions​

Permission Set Templates​

permissionset 50100 "API Access - [Group]"
{
    Assignable = true;
    Caption = 'API Access - [Group]';

    Permissions =
        page "[EntityName] API" = X,
        tabledata "[SourceTable]" = RIMD;
}

permissionset 50101 "API Read - [Group]"
{
    Assignable = true;
    Caption = 'API Read Only - [Group]';

    Permissions =
        page "[EntityName] API" = X,
        tabledata "[SourceTable]" = R;
}

When to Create API Pages​

Create API pages when:

  • External systems need to integrate with BC
  • Mobile apps need data access
  • Power Platform needs to consume BC data
  • Automation/batch processes need programmatic access
  • Third-party applications need REST endpoints

Don't create API pages when:

  • Only internal BC users need access (use regular pages)
  • One-time data migration (use XMLports or DataExchange)
  • Complex UI interactions required (use client pages)

Tips & Tricks​

  1. Use SystemId for ODataKeyFields — more stable than business keys
  2. DelayedInsert = true — better API POST behavior
  3. Test with Postman — easier than browser for POST/PATCH/DELETE
  4. Version early — plan for v2.0, v3.0 from the start
  5. Document endpoints — create OpenAPI/Swagger documentation
  6. Monitor performance — use telemetry to track API usage
  7. Handle etags properly — use If-Match header for concurrency