preUpload

Since: Editor 1.7.3

Triggered prior to each file being uploaded (cancellable).
Please note - this property requires the Editor extension for DataTables.

Description

This event is triggered whenever a file is uploaded (upload / uploadMany) by the end user. It can be used to modify the data being sent to the server as part of the upload, or to cancel the upload action after client-side validation has been performed.

Please note that in the case of uploadMany, if the user selects multiple files to be uploaded, this event will be triggered once for each file selected for upload. Each file can than be cancelled or not as required.

This event is cancellable by returning false from the event handler.

As of Editor 2.0.5 this event will accept a Promise as the returned value, allowing async actions such as client-side manipulation of the images to upload.

Type

`function( e, fieldName, file, ajaxData )`

Parameters:

	Name	Type	Optional
1	`e`	`object`	No
	Event object
2	`fieldName`	`string`	No
	The name (`fields.name`) of the field that the file is being uploaded for.
3	`file`	`object`	No
	This object is a `File` instance for the file that is being uploaded. It contains: `lastModified` - Epoch milliseconds `name` - File name `size` - File size in bytes `type` - MIME type of the file Please see the `File` documentation on MDN for full details of this object.
4	`ajaxData`	`object`	No
	The `FormData` object that will be used to send information to the server. Additional information can be added, or existing information modified here. Editor will send the following parameters: `action` - The action the server is to perform, in this case it will be `upload`. `uploadField` - The field name for the file being uploaded `upload` - The file data from the `file` object for the upload

Returns:

boolean:
Return false to stop the upload action. This will leave the form in the same state that it previously was. If you need to show an error message to the end user, this must be done with another API call (e.g. field().error()).

Examples

Client-side file size validation:

editor.on( 'preUpload', function ( e, fieldName, file, ajaxData ) {
		if ( file.size > 50000 ) {
			editor.field( fieldName ).error('File must be smaller than 50K');
			return false;
		}
		else {
			editor.field( fieldName ).error(''); // Clear any old errors
		}
	} );

Use with a Promise:

editor.on('preUpload', function (e, name, file, data) {
		var p = new Promise((resolve, reject) => {
			// Manipulation of the image in `data` could be done here
			// ...

			setTimeout(() => {
				resolve();
			}, 5000);
		});

		return p;
	})
;

The following options are directly related and may also be useful in your application development.

Events

Options