ListField

import { ListField } from "@prestojs/viewmodel";

A container field for an array of values

You must pass childField which is the underlying field for each value in the list. ListField will call format, parse, and normalize on this field for each value in the list.

By default defaultValue will be set to an empty array unless blankAsNull is true in which case it will be set to null. normalize and parse also behave in the same way (a falsy value passed to these will either return an empty array when blankAsNull is false or null when it is true).

const listOfInts = new ListField({ childField: new IntegerField() });

API

Constructor

new ListField(props)

Source

	Parameter	Type
*	props.blankAsNull	undefined\|false\|true
*	props.childField	Field
*	props.defaultValue	null\|T[]\| Function
*	props.rest	rest

Methods

format(value)

Source

Calls childField.format on each entry in the passed array

	Parameter	Type	Description
*	value	T[]

Returns

any

isEqual(value1,value2)

Source

	Parameter	Type	Description
*	value1	T[]
*	value2	T[]

Returns

boolean

normalize(value)

Source

Calls childField.parse on each entry in the passed array

If value is falsy or an empty array and blankAsNull is true it will return null or if blankAsNull is false then it will return an empty array.

	Parameter	Type	Description
*	value	any

Returns

One of the following:

T[]

null

parse(value)

Source

Calls childField.parse on each entry in the passed array

If value is falsy or an empty array and blankAsNull is true it will return null or if blankAsNull is false then it will return an empty array.

	Parameter	Type	Description
*	value	ParsableType[]\|null

Returns

One of the following:

T[]

null

Properties

childField: Field

Static Properties

fieldClassName: string

Inherited Methods

clone()

Source

Returns a clone of the field that should be functionally equivalent

Returns

Field

contributeToClass(viewModel)

Source

Called once after fields are attached to a ViewModel. This occurs the first time .fields is accessed on the ViewModel.

By default this does nothing but can be used by fields to attach extra properties or validate against the final view model (for example checking that another field does / does not exist).

NOTE: This is called for every distinct ViewModel class; so if class A is extended by class B then it will be called on both A and B.

	Parameter	Type	Description
*	viewModel	ViewModel Class

Returns

void

toJS(value)

Source

Convert value to plain JS representation useful for things like passing to a form or posting to a backend API

	Parameter	Type	Description
*	value	T[]

Returns

One of the following:

string

number

null

__type

toString()

Source

Returns

string

Inherited Properties

asyncChoices: AsyncChoicesInterface

Async choices for this field.

blank: boolean

Is this field required when saving a record?

blankAsNull: boolean

If true an empty string value should be converted to a null value

boundRecord: ViewModel

When accessed on a bound field will return the current instance of the ViewModel the field is bound to.

If called on an unbound field then this will always be undefined and a warning will be raised.

choices: Map

defaultValue: Promise<T[]|null|undefined>|T[]|null|undefined

Get the default value for this field.

helpText: string

Help text that can be displayed with the form widget

isBound: boolean

Returns true if field is bound to a ViewModel instance. When a field is bound to a instance the value for that field is accessible on the 'value' property.

label: string

Label that can be displayed as the form label for a widget

If not specified will be generated from name.

model: ViewModel Class

The ViewModel class this field is attached to.

This will throw an error if the field is not attached to a model.

name: string

The name of this field.

This will throw an error if the field is not attached to a model.

readOnly: boolean

Indicates this field should only be read, not written. Not enforced but can be used by components to adjust their output accordingly (eg. exclude it from a form or show it on a form with a read only input)

value: T[]

When isBound is true this will return the current value of this field on the bound ViewModel. Otherwise will always be undefined.

writeOnly: boolean

Indicates this field should only be written only and is not intended to be read directly. This is not enforced but can be used by components to adjust their output accordingly (eg. exclude it from a detail view on a record)