Event and form helpers

Contract

v0.1.19 adds ergonomic bus-ui helpers around the typed GX event payloads from v0.1.15 and the browser adapters from v0.1.16 form values and files. The helpers keep native HTML-like event names such as onClick, onSubmit, onInput, and onChange, while giving handlers ordinary Go access to target metadata, form values, files, keyboard data, focus transitions, and drag/drop items.

import (
	"github.com/busdk/bus-gx/pkg/gx"
	"github.com/busdk/bus-ui/pkg/uikit/uievent"
)

func SaveForm(client DraftClient) func(gx.SubmitEvent) {
	return func(event gx.SubmitEvent) {
		event.PreventDefault()

		form, err := uievent.Form(event)
		if err != nil {
			return
		}

		client.Save(Draft{
			Title:     form.Value("title"),
			Submitter: form.SubmitterName(),
		})
	}
}

Helper Reference

uievent.Form(event gx.SubmitEvent) (Form, error) returns form values, submitter id/name/value, data-* attributes, and prevent-default state. It returns an error when no form source is available.

uievent.Input(event gx.InputEvent) Input returns current value, checked state when available, and target identity. Missing browser fields become zero values.

uievent.Files(event gx.FileInputEvent) ([]uievent.File, error) returns safe file metadata and reader handles through the file adapter. It returns an error when browser file access is unavailable.

uievent.Keyboard(event gx.KeyboardEvent) Keyboard returns key, code, modifier flags, and repeat state.

uievent.Focus(event gx.FocusEvent) Focus returns source and destination target snapshots when the browser provides them.

uievent.Drop(event gx.DragEvent) (Drop, error) returns drag/drop item metadata and file handles through the same file adapter boundary as file inputs. It returns an error when browser drag data is unavailable.

The helper values expose a compact surface:

Value Key API Defaults and Constraints
Form Value(name string) string, Values(name string) []string, SubmitterID() string, SubmitterName() string, SubmitterValue() string, Data(name string) string, DefaultPrevented() bool Value returns the first value. Values preserves repeated form fields in DOM order. Missing fields return "" or an empty slice.
Input Value string, Checked bool, Target gx.EventTarget, Data(name string) string Missing value is ""; missing checked state is false.
File Name string, Size int64, Type string, Open(ctx context.Context) (io.ReadCloser, error) Matches the file adapter. Missing type is ""; empty selections return an empty list.
Keyboard Key string, Code string, Alt bool, Ctrl bool, Meta bool, Shift bool, Repeat bool Missing string fields are ""; missing modifiers are false.
Focus Target gx.EventTarget, RelatedTarget gx.EventTarget Missing related target is the zero target.
Drop Target gx.EventTarget, Files []File, Data(name string) string Missing data returns ""; missing files return an empty list.

Requirements

  • Helpers wrap typed Go payloads and never expose raw JavaScript values.
  • Form helpers preserve repeated field names.
  • File helpers expose metadata and reader handles, not raw browser objects.
  • Drag/drop helpers share the file safety rules used by file inputs.
  • Prevent-default behavior is explicit and observable in tests.
  • Missing browser fields become zero values or empty collections.

Boundary

This patch does not upload files, fetch resources, store sessions, or own business validation. Product modules still validate form meaning, file policy, authorization, and provider-specific request bodies.

UI framework index

Sources