summercms/docs/backend/forms.md

---
title: Forms
description: Describe admin forms in config_form.yaml and fields.yaml, with the supported field types, spans, tabs, dropdown options and create or update contexts.
section: backend
order: 20
---
# Forms

The Form behaviour's `config_form.yaml` and the model's `fields.yaml` keep their WinterCMS shape. [cabana](../../modules/cabana/README.md) compiles them strictly at boot: an unknown key, field type, span or size stops the start-up with an error naming the file and the field, so a WinterCMS option that SummerCMS does not implement is never ignored silently.

## config_form.yaml

The controller's form configuration names the fields file with a WinterCMS path, the model class, and where the SPA goes after a save:

```yaml src=modules/cabana/testdata/docs/controllers/posts/config_form.yaml
name: acme.blog::lang.posts.form
form: ~/plugins/acme/blog/models/post/fields.yaml
modelClass: Post
defaultRedirect: acme/blog/posts
create:
    redirect: acme/blog/posts/update/:id
    redirectClose: acme/blog/posts
update:
    redirect: acme/blog/posts
    redirectClose: acme/blog/posts
```

`modelClass` must equal the controller's `pact.AdminController.ModelName`. The `~/plugins/<vendor>/<plugin>/` prefix points into the plugin's own embedded tree.

An optional `recordActions` key lists the record actions the form offers, by the names the controller registers through `pact.HasAdminRecordActions`. It needs a `preview` block, because record actions are offered on the [preview screen](#preview-screen). The show response of a record then carries `meta.actions`: the declared actions the administrator may run and that apply to the record in its current state. See [Record actions](admin-controllers.md#record-actions).

## fields.yaml

```yaml src=modules/cabana/testdata/docs/models/post/fields.yaml
fields:
    title:
        label: acme.blog::lang.posts.title_column
        type: text
        span: left
        required: true
    slug:
        label: acme.blog::lang.posts.slug
        type: text
        span: right
        context: update
        comment: acme.blog::lang.posts.slug_comment
    status:
        label: acme.blog::lang.posts.status
        type: dropdown
        span: left
        options:
            draft: acme.blog::lang.posts.draft
            published: acme.blog::lang.posts.published
    published:
        label: acme.blog::lang.posts.published
        type: switch
        span: right
    content:
        label: acme.blog::lang.posts.content
        type: textarea
        size: large
        tab: acme.blog::lang.posts.tab_content
```

The compiled schema keeps the fields in file order, with their labels as translation keys until a request asks for them in its locale:

```go src=modules/cabana/example_test.go#ExampleCompileForm
fsys := os.DirFS("testdata/docs")
form, err := cabana.CompileForm("acme.blog", PostsController{}, fsys)
if err != nil {
	fmt.Println(err)
	return
}
for _, f := range form.Fields {
	fmt.Printf("%s %s span=%q tab=%q required=%v options=%d\n", f.Name, f.Type, f.Span, f.Tab, f.Required, len(f.Options))
}
// Output:
// title text span="left" tab="" required=true options=0
// slug text span="right" tab="" required=false options=0
// status dropdown span="left" tab="" required=false options=2
// published switch span="right" tab="" required=false options=0
// content textarea span="" tab="acme.blog::lang.posts.tab_content" required=false options=0
```

### Field types

| Type | Renders |
|------|---------|
| `text`, `textarea`, `number` | Text inputs. |
| `checkbox`, `switch` | Booleans. |
| `dropdown` | A select. Options are a map in the YAML, or the name of a method the controller answers through `pact.DropdownOptionsProvider`. |
| `relation` | A belongsTo or belongsToMany picker; see [Relation manager](relation-manager.md). |
| `relation-manager` | An embedded list of related records; see [Relation manager](relation-manager.md). |
| `widget` | A plugin custom element with a server action; see [Partials and widgets](partials-and-widgets.md). |
| `partial` | A server-rendered template; see [Partials and widgets](partials-and-widgets.md). |
| `fileupload` | Uploads for an attachOne or attachMany relation; see [File uploads](#file-uploads). |
| `datepicker` | A date, date and time, or time of day; see [Date pickers](#date-pickers). |
| `permissioneditor` | A list of permissions to allow, deny or leave inherited; see [Permission editor](#permission-editor). |
| `password` | A masked input with a show and hide button. It is a form-only field: the value is sent with a save and never returned; see [Form-only fields](#form-only-fields). |

The WinterCMS widgets that are not in this list (the rich editor, the markdown editor, the code editor, the color picker, the media finder, the repeater, the tag list and the others) are not provided. A field with one of those types stops the start-up.

### Field options

A field takes `label`, `comment`, `type`, `required`, `default`, `tab`, `span` (`left`, `right`, `full`, `auto`, `row`), `size` (`tiny`, `small`, `large`, `huge`, `giant`), `context`, `attributes` (scalar HTML attributes for the input), `options` and `emptyOption`, plus `nameFrom` and `relation` on relation fields and `preset` on text fields. WinterCMS keys outside this set, such as `readOnly`, `disabled`, `trigger` or `dependsOn`, are refused.

`context: update` shows a field only on the update form, and `context: create` only on the create form; a list of contexts is also accepted, and `context: preview` shows a field only on the [preview screen](#preview-screen). The context is enforced on the server too: a field that is hidden on a form is never written by that form's save, whatever the request body holds.

`preset` makes a `text` field follow another text field of the same form while the administrator has not edited it, as a slug field follows a title. It is the source field's name, or a mapping with `field` and `type`:

```yaml
slug:
    label: acme.blog::lang.posts.slug
    type: text
    preset:
        field: title
        type: slug
```

`type: slug` (the default, and what the short form `preset: title` means) lower-cases the text and turns every run of characters other than ASCII letters and digits into one hyphen; `type: exact` copies the text. The admin SPA applies it on the create form only, and the first manual edit of the field stops it. The server does not fill the field: a model that needs a slug even when none is sent sets it in its own `BeforeValidate`. The schema reports the key as `preset` (a `cabana.FieldPreset`). A `preset` on another field type, an unknown type, or a source that is not a text field of the same form stops the start-up, and the key is not accepted on settings forms or relation forms.

## Date pickers

A `type: datepicker` field edits one model column. Its `mode` decides the column's Go type, and the start-up stops when they do not match:

| `mode` | Go type of the column | JSON value |
|--------|------------------------|------------|
| `datetime` (the default) | `time.Time` or `*time.Time` (a `timestamptz` column) | `"2026-10-02T10:30:00Z"` |
| `date` | `lagoon.Date` or `*lagoon.Date` (a `DATE` column) | `"2026-10-02"` |
| `time` | `lagoon.TimeOfDay` or `*lagoon.TimeOfDay` (a `TIME` column) | `"14:30:00"` |

A plugin does not define its own date types; see [Casts and validation](../database/casts-and-validation.md) for the two framework types. Use the pointer types for an optional value: an empty picker stores NULL, and `required: true` refuses it.

```yaml
fields:
    published_on:
        label: acme.blog::lang.posts.published_on
        type: datepicker
        mode: date
        minDate: 2000-01-01
    starts_at:
        label: acme.blog::lang.posts.starts_at
        type: datepicker
        format: d.m.Y H:i
        firstDay: 1
```

The field takes the generic keys plus these WinterCMS keys:

| Key | Meaning |
|-----|---------|
| `mode` | `date`, `datetime` or `time`. |
| `format` | The display format as a PHP `date()` format. It is turned into the SPA's format at boot (the schema serves it as `displayFormat`); a letter with no equivalent, such as `T`, `U` or `c`, stops the start-up. It changes only how the value is shown, not the order of the editable segments, which follows the admin's locale. |
| `minDate`, `maxDate` | The earliest and latest calendar date (`YYYY-MM-DD`). Not valid on `mode: time`. |
| `yearRange` | Years either side of today (`10`) or a `[from, to]` list for the year selector. |
| `firstDay` | The first day of the week, 0 (Sunday) to 6. |
| `twelveHour` | Shows a 12-hour clock. |
| `ignoreTimezone` | `mode: datetime` only: the value is shown and saved as entered, with no time zone conversion. |

`options`, `emptyOption`, `nameFrom` and every other key stop the start-up.

`minDate` and `maxDate` are checked again on save: a value whose calendar date (the UTC date of a datetime, or its wall-clock date with `ignoreTimezone`) lies outside them is a 422 on the field. A `datetime` value is stored in UTC and the admin SPA shows and edits it in the browser's time zone; `date` and `time` values are never converted. The datetime picker's calendar popover also has a time field, so the clock can be set without typing in the input.

## File uploads

A `type: fileupload` field edits one attachment relation of the form's model. The model declares its relations with an `AttachRelations` method (`attach.HasRelations`) and implements `attach.Owner`; see [Attachments](../database/attachments.md). The field name must be one of the declared relation names, otherwise the start-up stops.

```yaml
fields:
    photos:
        label: acme.blog::lang.posts.photos
        type: fileupload
        mode: image
        fileTypes: jpg,png,webp
        maxFilesize: 5
        maxFiles: 10
        thumbOptions:
            mode: crop
```

The field takes the generic keys plus these WinterCMS keys:

| Key | Meaning |
|-----|---------|
| `mode` | `image` or `file` (the default). Image mode accepts only jpg, jpeg, png, gif and webp and checks that the bytes decode as such an image. |
| `fileTypes` | Allowed extensions, as a comma- or pipe-separated string or a list. |
| `mimeTypes` | Allowed MIME types (`image/png`, `image/*`) or extensions. |
| `maxFilesize` | The largest file in megabytes. The file plus 64 KiB of multipart framing may not exceed `http.body_limits.upload_bytes`. |
| `maxFiles` | The most files an attachMany relation may hold. Refused on attachOne. |
| `imageWidth`, `imageHeight` | Preview size, 1 to 4096 pixels (240 by 240 when not set). |
| `thumbOptions` | A mapping with `mode`: `auto`, `exact`, `crop` (the default) or `fit`. |
| `useCaption` | Lets the administrator edit each file's title and description. |
| `prompt` | The upload button text, a translation key. |

`options`, `emptyOption`, `nameFrom` and every other key stop the start-up.

Uploads are deferred until the form is saved, on the create form and the update form alike, as WinterCMS's file upload widget does. The admin SPA makes a random session key when it opens a form and sends it in the `X-Session-Key` header with every upload and with the save. The upload stores the file unattached and records a pending binding for that key and the signed-in administrator; the record's create or update save attaches every pending file of the form's fileupload fields inside its own transaction. If the save fails with a 422, the uploads stay pending for the next attempt; if the form is left without saving, the daily `deferred:purge` removes them. A session key is only ever seen by the administrator who used it.

Removing a file is deferred the same way: the file disappears from the form at once and is deleted by the save (a pending upload that is removed is deleted at once). On an attachOne relation, saving a new upload deletes the file it replaces. Captions (with `useCaption`) and the order of an attachMany field are saved at once, as in WinterCMS. After applying the session's work, the save checks `maxFiles` and, for a `required: true` fileupload field, that at least one file is attached; a failure is a 422 on the field and keeps the pending work. Files of a protected relation are shown through authenticated admin routes only; see [Protected files in the admin](../database/attachments.md#protected-files-in-the-admin).

The limits are enforced on the server: the upload route caps the request body at the smaller of `http.body_limits.upload_bytes` and `maxFilesize` plus 64 KiB (413 `payload_too_large` past it), and a file that is too large, of a type the field does not allow, or not a valid image in image mode is a 422 on the field.

## Preview screen

A form may have a read-only screen in front of its update form, as WinterCMS's preview context: the list opens the record there, the administrator reads it, runs a record action or presses the edit button. A `preview` block in `config_form.yaml` turns it on:

```yaml src=modules/cabana/testdata/roster/controllers/people/config_form.yaml
name: acme.roster::lang.people.form
form: ~/plugins/acme/roster/models/person/fields.yaml
modelClass: Person
defaultRedirect: acme/roster/people
create:
    redirect: acme/roster/people/preview/:id
    redirectClose: acme/roster/people
update:
    redirect: acme/roster/people
    redirectClose: acme/roster/people/preview/:id
preview:
    headerPartial: status
recordActions: [activate, reinstate]
messages:
    preview: acme.roster::lang.people.preview
    edit: acme.roster::lang.people.edit
```

- `preview` is a mapping. `headerPartial: <name>` names a controller partial rendered above the fields as a status hint (see [Partials and widgets](partials-and-widgets.md#status-hints)); write `preview: {}` for a screen without a hint. An empty `preview:` key, any other key inside it, or a `recordActions` list without a `preview` block stops the start-up.
- The form schema reports the block as `preview` (a `cabana.FormPreview`), and the SPA then serves the record at `<controller>/<id>/preview`. A form without the block has no such screen: the route goes to the update form.
- The screen shows every field whose `context` allows `preview`. A field without a `context` shows on every screen; `context: preview` shows a field only here. Values are rendered as text; `widget` and `relation-manager` fields are not shown.
- A field with `context: preview` is never written. A save asks only for the `create` or the `update` context, so such a field in a request body is dropped like any field hidden on that form.
- `messages.preview` is the screen's subtitle and `messages.edit` the label of its edit button; both default to framework texts (`cabana.FormMessages`).
- `recordUrl` in `config_list.yaml` and the form's `create.redirect`, `update.redirectClose` and the other redirects may point at the screen as `<vendor>/<plugin>/<controller>/preview/:id`. On the update form of a record with a preview, the back arrow and Cancel return to the preview; after a delete the form goes to the list.
- The footer holds the record actions the show response offers in `meta.actions`, then the edit button. After an action the record and the status hint are loaded again in place.

## Form-only fields

Some fields of a form are not columns of the record: a password and its confirmation, or a "send an invitation" checkbox. A controller lists them through `pact.FormVirtualFields`:

```go src=modules/cabana/example_form_seams_test.go#MembersController.FormVirtualFields
// FormVirtualFields names the fields of fields.yaml that are not columns of
// the form. cabana never fills or returns them.
func (MembersController) FormVirtualFields() []string {
	return []string{"password", "password_confirmation", "notify"}
}
```

- A listed field needs no model column. cabana never binds it, never fills it into the model and never puts it in a record response, on any route. A model column with the same name (a stored password hash) is not touched by the form.
- The values an administrator submits reach the controller's Form hooks through `cabana.VirtualFieldsFromContext(ctx)`; see [Admin controllers](admin-controllers.md#form-only-values-and-rules). Only fields that were sent and whose `context` allows the operation are there. A value must be a scalar: an object or a list is a 422 on the field.
- Every listed name must be a field of the form's `fields.yaml` with the type `password`, `text`, `textarea`, `number`, `checkbox`, `switch` or `dropdown`. Anything else stops the start-up.
- `type: password` is always a form-only field: a password field the controller does not list stops the start-up. The admin SPA shows it empty on every load, leaves an empty password out of an update (empty means unchanged), and clears it after a save. A confirmation is a second `password` field, compared by the `confirmed` rule on the server.
- Form-only fields are not available on settings forms or relation forms.

## Permission editor

`type: permissioneditor` edits a set of permissions on a record: which codes are allowed, and in radio mode which are denied. The field needs a `mode`:

```yaml
permissions:
    label: acme.roster::lang.people.permissions
    type: permissioneditor
    mode: radio
    tab: acme.roster::lang.people.tab_permissions
    context: update
```

| Mode | Control per permission | Values |
|------|------------------------|--------|
| `radio` | Allow, Inherit, Deny | `1` allows, `-1` denies; an inherited permission has no value. |
| `checkbox` | One checkbox | `1` allows; an unchecked permission has no value. |

The permissions themselves are not in the YAML. The controller implements `cabana.PermissionEditorProvider` and answers per request, so the list may depend on the signed-in administrator:

```go src=modules/cabana/example_form_seams_test.go#MembersController.AdminPermissionOptions
// AdminPermissionOptions lists the permissions the `type: permissioneditor`
// field offers, in display order. The principal on ctx decides what is locked.
func (MembersController) AdminPermissionOptions(ctx context.Context, field string) ([]cabana.PermissionOption, error) {
	principal, _ := bouncer.User(ctx)
	mayExport := cabana.Allows(principal, []string{"acme.roster.manage"})
	return []cabana.PermissionOption{
		{Code: "posts.edit", Label: "acme.roster::lang.permissions.posts_edit", Tab: "acme.roster::lang.permissions.tab_content"},
		{Code: "posts.publish", Label: "acme.roster::lang.permissions.posts_publish", Tab: "acme.roster::lang.permissions.tab_content"},
		{Code: "reports.export", Label: "acme.roster::lang.permissions.reports_export", Tab: "acme.roster::lang.permissions.tab_reports", Locked: !mayExport},
	}, nil
}
```

```go src=modules/cabana/example_form_seams_test.go#MembersController.AdminPermissionValues
// AdminPermissionValues reads the permissions stored on the record.
func (MembersController) AdminPermissionValues(_ context.Context, field string, record any) (map[string]int, error) {
	values := map[string]int{}
	if raw := record.(*Member).Permissions; raw != "" {
		if err := json.Unmarshal([]byte(raw), &values); err != nil {
			return nil, err
		}
	}
	return values, nil
}
```

```go src=modules/cabana/example_form_seams_test.go#MembersController.AdminSetPermissionValues
// AdminSetPermissionValues stores the checked set on the model. The save
// writes the row afterwards, in the same transaction.
func (MembersController) AdminSetPermissionValues(_ context.Context, field string, record any, values map[string]int) error {
	raw, err := json.Marshal(values)
	if err != nil {
		return err
	}
	record.(*Member).Permissions = string(raw)
	return nil
}
```

- An option (`cabana.PermissionOption`) has a `Code`, a `Label`, and optionally a `Tab` and a `Comment`; the three texts are translation keys or text. Options with the same `Tab` are shown as one section of the list, in the order the controller returns them, and options without a `Tab` form a last section. The form schema carries them on the field as `permissionOptions`.
- The value travels as a JSON object of code to integer, in a record response and in a save body: `{"posts.edit": 1, "posts.publish": -1}`. A record response always carries the object, empty when nothing is stored.
- A save checks the submitted object inside its transaction, after the Form before-hooks and before the row is written. A value that is not an object of integers, a code the controller does not offer, or a value outside the mode's set is a 422 on the field; a `0` means "no value". The checked set is then handed to `AdminSetPermissionValues`, which decides how it is stored.
- A stored code that is not among the options is kept as it is: an offered code that is left out loses its value, a code that is not offered is never touched and can never be submitted.
- An option with `Locked` set is shown with a disabled control. The server enforces it: a save in which a locked code's value differs from the stored one is answered 403 `forbidden` with a message on the field, and nothing is written.
- A locked code must be stored with a value its mode can send: 1, -1 or no value in radio mode, 1 or no value in checkbox mode. The admin sends only those values, so a locked code stored with anything else never matches, and every save of that record from the admin form is refused for that administrator. Normalize stored values before locking a code.
- A save that does not send the field leaves the stored permissions alone, and the field's `context` applies as for any field.
- The keys `options`, `default`, `nameFrom`, `emptyOption`, `relation` and `preset` are refused on the type. A field without `mode`, or on a controller that does not implement the provider, stops the start-up. The type is not available on settings forms or relation forms.

## What a save may write

The form's writable fields are bound to model columns at boot. A save passes only those fields that are also in the model's `Fillable` list, drops unknown keys, case variants and nested objects, and fills the model with `lagoon.Fill` (see [Models](../database/models.md)). The model's validation rules (a `Rules` method returning `lagoon.Validate` rule strings) and the form's `required` flags are checked in the save's transaction, and a failure is a 422 with messages per field. A value that does not fit its column is also a 422 on that field. A controller implementing `pact.FormRules` supplies its own rule set per operation, which replaces the model's rules for admin saves.

[Form-only fields](#form-only-fields) are never written by cabana. Their submitted values are validated, when a rule names them, and handed to the controller's hooks; what is stored from them is the hook's decision.