RunEvent Overview
The RunEvent handler is the primary backend endpoint that processes all form events and controls form behavior dynamically from the server.
Basic Concepts
Understanding the request and response structure is essential for implementing your runEvent handler.
Button Click Events
Button click events are the most common widget events. They trigger actions like saving data, opening forms, downloading files, or displaying messages.
Field Change Events
Field change events trigger when a user modifies field values. Use these to calculate dependent values, validate input, or load related data.
Datatable Events
The datatable widget is one of the most complex components and triggers multiple event types. Understanding these events is crucial for proper backend implementation.
Form Lifecycle Events
Form lifecycle events allow you to hook into key moments in a form's existence: when it loads, saves, or closes.
File Upload Events
File upload events handle file uploads through form widgets or datatable upload buttons. These events use multipart form data instead of JSON.
Frontend Commands
Frontend commands (feCommand) are actions that the form viewer executes after receiving your runEvent response. Use these commands to control the user interface from your backend.
Event Reference
Complete list of all available widgetEvent types in the Buildocs UI Engine system.