alter-page

ALTER PAGE / ALTER SNIPPET - Modify Existing Pages and Snippets

Overview

ALTER PAGE and ALTER SNIPPET modify an existing page or snippet's widget tree in-place without requiring a full create or replace. Operations work directly on the raw BSON tree, preserving widget types and properties that MDL doesn't explicitly model.

When to Use

Scenario	Use
Change a button caption, label, or style	alter page with set
Add a field to an existing form	alter page with insert
Remove unused widgets	alter page with drop
Replace a footer or section	alter page with replace
Several related changes on the same page	alter page with multiple operations in one block
Same property across many pages (e.g., add Class to every Container)	update widgets — see bulk-widget-updates
Rebuild entire page from scratch	create or replace page
Create a new page	create page

Rule of thumb:

• alter page — targeted edits to one page. Combine multiple ops in one block when they belong together.
• update widgets — cross-page bulk updates with WHERE filtering and DRY RUN.
• create or replace page — redefining the full page structure.

Syntax

alter page Module.PageName {
  operation1;
  operation2;
  ...
};

alter snippet Module.SnippetName {
  operation1;
  operation2;
  ...
};

Multiple operations can be combined in a single ALTER statement. They are applied sequentially; later operations see the page state produced by earlier ones, so you can set on a widget you just inserted.

-- Rename a column, add a sibling, drop an obsolete one — all in one block.
alter page MyMod.Product_Overview {
  set caption = 'Product Name' on dgProducts.Name;
  insert after dgProducts.Lifecycle {
    column NewCol (attribute: Sku, caption: 'SKU')
  };
  drop widget dgProducts.OldCol
};

For changes that should be applied across many pages (e.g., "add Class='card' to every Container in MyMod"), use UPDATE WIDGETS instead — see bulk-widget-updates.