AsyncChoicesInterfaceTypescript Type
SourceInterface for asynchronous choices. If you wish to write a compatible class for
use with asyncChoices you must conform to this interface. See AsyncChoices
for a concrete implementation that is suitable for most cases.
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:
- A function to resolve existing value(s). This is used when viewing existing value(s) and need label(s) to show (e.g. when displaying a choice on a detail view or rendering the value selected on a select widget).
- A function to list & filter the available choices. This is used when selecting a value (e.g. 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. These 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.
See useAsyncChoices for a React hook to use async choices.
Methods
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.
A single choice looks like:
const choice = { value: 1, label: "Item 1", }
Grouped choices are an array of 2-tuples, the group label and choices for that label:
const choicesGrouped = [ [ "Group1", [ { value: 1, label: "Item 1" }, { value: 2, label: "Item 2" }, ], ], ["Group 2", [{ value: 3, label: "Item 3" }]], ]
Either an array of single choices or grouped choices.
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.
Get the value to use for an item. The value should be unique and is what's used when a choice is selected (e.g. it's the value that would be saved to a database).
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 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.
Given a value parse it into the expected type.
For example, if the value comes in as a string (e.g. from a URL query parameter) then this could
parse the value as a number so it matches the id returned from the server.
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.
Arguments:
| Argument | Type | Description | |
|---|---|---|---|
| * | value | ValueType|ValueType[] | The value(s) to retrieve. If |
| deps | any |
Hook that returns any extra props to pass through to list in components/hooks that
consume this (eg. 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 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.
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.
Hook that returns props to pass through to retrieve in components/hooks that consume this (eg. useAsyncChoices.
This is useful for things like hooking into an existing cache (eg. 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 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.
Properties
multiple
SourceIf true then multiple values can be selected. When this is true retrieve() will be passed and return an array rather than a single value.