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Subscribe to Power Apps events

Power Apps provides a lot of events that can be subscribed to. For example, when a form is loaded, when a column value is changed or when a command-bar button is clicked.

With Primno, a Power Apps event can be subscribed using decorators in a component. It must be associated with a method that will be the event handler called when the event occurs.

Each events decorator is prefixed with MnOn and the event name is in pascal case. For example, the Form load event is associated with the @MnOnFormLoad() decorator.

Subscribe to the form load event.
@MnOnFormLoad()
public onFormLoad(eventArg: FormEventArgs) {
    // Do something
}
info

Each event decorator has a dedicated documentation page that provides explanations and usage examples. See the full events list.

Eg: MnOnColumnChange.

Page type​

The page type define the main source of the event:

Page typeDescription
RecordFired on a form (principal form, quick create form).
ListFired on a home-grid, sub-grid or associated grid.

A event can be available on one or both page types. For example, the form load event is only available on a record page when the enable rule (command-bar) event is available on both record and list pages. See the full events list.

A component defines its page type using the Scope property of its MnComponent decorator.

caution

A component targeting the "List" page type cannot subscribe to a "Record" event and vice versa.

The page type defined the execution context of the event handler, a record event performs operations on a form (form context) when a list event performs operations on a grid (grid context).

Event handler​

The event handler is a component method that will be called when the event occurs.

It's argument depends on the event that occurred. For example, the column change event will contain the context of the form on which it is executed, whereas the command invoke event will contain the context of the associated grid control or form.

Target​

Some events require a target to be subscribed. A target can be a column, control or command name. For example, MnOnColumnChange requires a column name, whereas MnOnFormLoad doesn't.

The target is specified in the decorator as a string argument or function that returns a string from the component configuration. See Component configuration.

tip

Use the ConfigOf type to get the type of the component configuration.

Example:

@MnComponent({
    scope: {
        pageType: "record",
        table: 'account'
    }
})
export class MyComponent {
    @MnConfig({
        column: 'name'
    })
    config: {
        column: string;
    };

    /**
     * Subscribe to the column change event of the hard-coded column 'accountnumber'.
     */
    @MnOnColumnChange('accountnumber')
    public onAccountNumberChange(eventArg: FormEventArgs) {
        // Do something
    }

    /**
     * Subscribe to the column change event of the column specified in the configuration, here 'name'.
     */
    @MnOnColumnChange((cfg: ConfigOf<NotificationComponent>) => cfg.notificationColumn)
    public onColumnChange(eventArg: FormEventArgs) {
        // Do something
    }
}