FileWidget

File upload widget that wraps the antd [Upload](https://ant.design/components/upload/#API) component. Unlike
that component this one never uploads immediately - the raw [File](https://developer.mozilla.org/en-US/docs/Web/API/File)
object will be passed to `onChange` and it's expected the upload will happen externally (eg. on a form submit).

If `multiple` is true then the value passed to `onChange` will be an array of `File` objects or an empty array when clearing the value.

If `multiple` is false then the value passed to `onChange` will be a `File` object or `null` when clearing the value.

For very custom requirements consider using the [useFileList](doc:useFileList) in a custom component.

// TODO: Example: limit
// TODO: Example: multiple
// TODO: Example: custom children
// TODO: Example: drag and drop
// TODO: beforeUpload


props

UploadWidgetProps

ReactElement

checked

undefined

false

true

multiple

name

string

onBlur

__type

onChange

__call

onFocus

type

value

FieldValue

Properties

InputProps

HTMLElement

Any [AsyncChoices](doc:AsyncChoices), if applicable. This typically comes from [Field.asyncChoices](doc:Field#var-asyncChoices).

asyncChoices

AsyncChoicesInterface

Any choices, if applicable. This typically comes from [Field.choices](doc:Field#var-choices).

This can be a `Map` of value to label or an array of 2-element arrays `[value, label]`.


choices

The input props for the widget. This should include, at minimum:

- onChange
- value

Can also include

- name
- onBlur
- onFocus
- type
- checked
- multiple


input

Any extra details such as field errors, touched status etc. The values here depend on the form
library in use. If using [@prestojs/final-form](/docs/final-form/) see [FieldRenderProps](https://final-form.org/docs/react-final-form/types/FieldRenderProps)
for what this will be.

Record

WidgetProps

SingleValue

UploadWidgetInputType

Omit

Variables

The props from [Upload](https://ant.design/components/upload/#API). Note that `data`, `method`, `headers` and `withCredentials` are ignored as this component doesn't upload immediately.

UploadProps

children

limit

TestDataItem

number

label

constructor

new Record

item

__get

_key

getLabel

Constructors

Accessors

Methods

React.ReactNode

__index

Choice

If true then multiple values can be selected. When this is true
retrieve() will be passed and return an array rather than a single value.

boolean

getChoices

Generate the list of choices. This can return an array of single choices or grouped choices.

A grouped choice is a 2 element Array with a label and a list of choices.


items

getMissingLabel

Return label to use when an item can't be found. This can be used by widgets to control
what is rendered when an item for a value cannot be found (eg. when it's deleted or
when it's loading). The exact details of how this is used depend on the widget.

getValue

Get the value to use for an item. The value should be unique and is what's used when a
choice is selected (eg. it's the value that would be saved to a database).

ValueType

list

Function to resolve a list of choices based on the provided params.

What this function is passed depends on the implementation but when used with
[useAsyncChoices](doc:useAsyncChoices) it will be passed `query` (the query object eg. to
filter results with), `paginator` (the current paginator if any) and `listOptions` (any
additional options passed on the `listOptions` prop to `useAsyncChoices`).
Official presto widgets all use `useAsyncChoices` and so will use these parameters.


params

Promise

retrieve

Function to resolve specific values. This is used to know how to render the label for a value(s).

The first parameter is the value to retrieve (will be an array when `multiple` is true).

`deps` is the value returned by `useRetrieveProps`.


deps

useListProps

Hook that returns any extra props to pass through to `list` in components/hooks that
consume this (eg. [useAsyncChoices](doc:useAsyncChoices)). This is useful to
store state for things like pagination.

What this function is passed depends on the implementation but when used with
[useAsyncChoices](doc:useAsyncChoices) it will be `query` (the query object eg. to
filter results with) and `listOptions` (any additional options passed on the `listOptions`
prop to `useAsyncChoices`).
Official presto widgets all use `useAsyncChoices` and so will use these parameters.


args

useResolveItems

Resolve the specific instance of an item to use. By default this should just return `item`
but can be used to resolve a specific instance of a class from a cache for example.

useRetrieveProps

Hook that returns props to pass through to `retrieve` in components/hooks that consume this (eg. [useAsyncChoices](doc:useAsyncChoices).
This is useful for things like hooking into an existing cache (eg. [useViewModelCache](doc:useViewModelCache)).
The value returned here is passed as the second parameter to `retrieve`. In addition the `existingValues` key is
passed through to `useAsyncValue` as the list of items it can resolve existing values from.

What this function is passed depends on the implementation but when used with
[useAsyncChoices](doc:useAsyncChoices) it will be passed `id` if there's a current value
and it's not an array, `ids` if there's a current value and it is an array, `existingValues` which is
the values returned by `list` (may be null if `list` not yet called) and `retrieveOptions`
(any additional options passed on the `retrieveOptions` prop to `useAsyncChoices`).
Official presto widgets all use `useAsyncChoices` and so will use these parameters.


A choice is a `value` that identifies the item (eg. an id) and a `label` that
describes the item and is shown to users (eg. the name).

When `multiple` is true multiple values can be selected.

To define async choices two things are required:

1) A function to resolve existing value(s). This is used when viewing existing
   value(s) and need label(s) to show (eg. when displaying a choice on a detail
   view or rendering the value selected on a select widget).
2) A function to list & filter the available  choices. This is used when selecting
   a value (eg. the options shown in a select widget).

Both of these functions may need to store state (eg. pagination for a listing)
or access things from context (eg. read values from a cache). This can be done
via two hooks - `useListProps` and `useRetrieveProps`. This functions should be
called from a component or hook that deals with async choices when calling
`list` and `retrieve` respectively. The return value from the hook is passed to
the corresponding function.

For a default implementation see [AsyncChoices](doc:AsyncChoices)


AsyncChoices

ItemType

null

new AsyncChoices

options

AsyncChoicesInterface.multiple

AsyncChoicesOptions

AsyncChoicesInterface.getChoices

AsyncChoicesInterface.getLabel

AsyncChoicesInterface.getMissingLabel

AsyncChoicesInterface.getValue

AsyncChoicesInterface.list

AsyncChoicesInterface.retrieve

AsyncChoicesInterface.useListProps

AsyncChoicesInterface.useResolveItems

AsyncChoicesInterface.useRetrieveProps

Default implementation for [AsyncChoicesInterface](doc:AsyncChoicesInterface)

All options can be customised via `options`.

You must provide `list` and `retrieve` - everything else can be optional with the following restrictions:

* `getLabel` - this is optional if items returned by `list` and `retrieve` implement [NodeLabeled](doc:NodeLabeled) otherwise it must be provided
* `getValue` - this is optional if items returned by `list` and `retrieve` implement [Identifiable](doc:Identifiable) otherwise it must be provided


	Parameter	Type	Description
*	props		The props from Upload. Note that `data`, `method`, `headers` and `withCredentials` are ignored as this component doesn't upload immediately.
*	props.children	React.ReactNode	Contents to render (eg. upload button etc). If not provided renders default Icon or Button depending on `listType`
*	props.input	UploadWidgetInputType
*	props.limit	number\|null	Number of files to allow. `null` means unlimited. If `limit` is `1` then after uploading a file the UI will change from an Add icon to an Edit icon and uploading a new file will replace the original. If `limit` is > `1` then once the limit has been reached the UI will disallow adding new files. To add a new file an existing one must be removed. If `multiple` is `true` then the value passed to `onChange` will be an array, otherwise it will be a `File` object or null. It is valid to set `limit` to `1` and `multiple` to `true`. Defaults to `1`.
*	props.multiple	boolean	Whether multiple values are accepted. In most cases you can set `limit` to `null` or a value greater than `1` instead of explicitly setting this. This can be set to `true` when `limit` is `1` in order to enforce the value being an array (eg. this could be useful if `limit` increases based on something else). If true `input.value` must be an array when set and `onChange` will be passed an array of File objects, otherwise it will be passed a single value or null. If `multiple` is `true` and `limit` is 1 then the only difference to `multiple={false}` is that the `value` will be an array. Defaults to `false` if `limit` is `1` otherwise `true`.