model-binding.md

title	Model Binding and Default Values
sidebar_position	2

Fields read their starting value from the bound model, like the Blade components.

Precedence

1. Old input: Form old={…} / FormsProvider old={…}, when it has the field's key.
2. Bound value: the model's attribute (data_get with the name in dot notation).
3. default: when the bound value is null or missing.

A controlled value prop wins over all three. For Select / Select2, default wins over the bound value, as it does in Blade.

<Forms.Textarea name="motivation" default="I want to use this package because..." />
<Forms.Text name="title" model={post} />

<Forms.Form model={video}>
  <Forms.Text name="title" />            {/* video.title */}
  <Forms.Model model={video.profile}>
    <Forms.Textarea name="biography" /> {/* video.profile.biography */}
  </Forms.Model>
  <Forms.Text name="category_name" model={category} />
  <Forms.Textarea name="comments" model={false} />
</Forms.Form>

Bracket names read nested values: name="address[city]" reads address.city and submits address[city].

Fields that change after the first render

Fields are uncontrolled, so they submit natively like Blade forms. When the model, old input or default changes (for example, data that loads after the first render), the field resets to the new value. Pass value and onChange (or onValueChange / onCheckedChange) to control a field yourself.

Old input with Inertia

Share the flashed input and pass it once:

// HandleInertiaRequests::share
'old' => fn () => $request->session()->getOldInput(),

<FormsProvider old={usePage().props.old}>…</FormsProvider>