ManyRelatedViewModelField

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

Define a field that contains multiple records from another ViewModel

This behaves the same as RelatedViewModelField but sourceFieldName must refer to a ListField and all values are an array instead of a single value.

API

Constructor

new ManyRelatedViewModelField(props)

Source

	Parameter	Type	Description
	props.asyncChoices	AsyncChoicesInterface	Asynchronous choices for this field. Only one of `asyncChoices` and `choices` should be passed.
	props.blank	boolean	Is this field allowed to be assigned a blank (null, undefined, "") value? Defaults to false
	props.blankAsNull	boolean	Frontend values are often stored as strings even if they are not stored like that in a backend (eg. database). Depending on your backend implementation it may expect empty values to be represented as `null` rather than an empty string. Setting `blankAsNull` to `true` indicates that empty strings should be converted to `null` when being sent to the backend.
	props.choices	Map\|[SingleValueT, string][]	Choices for this field. Should be a mapping of value to the label for the choice.
	props.defaultValue	BaseRelatedViewModelValueType\|null\| Function	Default value for this field. This can either be a function that returns a value or the value directly.
	props.helpText	string	Optional help text for this field that might be shown on a form
	props.label	string	Label for this field. If not specified will be generated from the name.
	props.readOnly	boolean	True if field should be considered read only (eg. excluded from forms)
	props.writeOnly	boolean	True if field should be considered write only (eg. excluded from detail views)
	props.cache	ViewModelCache	The cache to use to retrieve related records from. Uses the default model cache if not specified.
*	props.sourceFieldName	SourceFieldNameT	The name of the field on the ViewModel that stores the ID for this relation
*	props.to	Function \|ViewModel Class	Either a ViewModel, a function that returns a ViewModel or a function that returns a `Promise` that resolves to a ViewModel.

Methods

normalize(value)

Source

Converts a value into the relations ViewModel instance.

	Parameter	Type	Description
*	value	any

Returns

RelatedViewModelValueType[]

toJS(value)

Source

Converts the linked record to a plain javascript object

	Parameter	Type	Description
*	value	RelatedViewModelValueType[]

Returns

Record

Static Properties

fieldClassName: string

Inherited Methods

clone()

Source

Returns a clone of the field that should be functionally equivalent

Returns

Field

format(value)

Source

Format the value for displaying in a form widget. eg. This could convert a Date into a localized date string

	Parameter	Type	Description
*	value	RelatedViewModelValueType[]

Returns

any

isEqual(value1,value2)

Source

Compares to relations for equality - if the ViewModel has the same data this returns true

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

Returns

boolean

parse(value)

Source

Parse a value received from a form widget onChange call. eg. This could convert a localized date string into a Date.

	Parameter	Type	Description
*	value	FieldDataMappingRaw[]\|null

Returns

One of the following:

RelatedViewModelValueType[]

null

resolveViewModel()

Source

Resolves the ViewModel this field links to. This is necessary as the ViewModel might be a dynamic import that hasn't yet loaded.

This needs to be called manually before to can be accessed.

Returns

Promise<ViewModel Class>

toString()

Source

Returns

string

Inherited Properties

_isResolvingDeps: boolean

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: ViewModelInterface

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.

cache: ViewModelCache

choices: Map

defaultValue: Promise<RelatedViewModelValueType[]|null|undefined>|RelatedViewModelValueType[]|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.

many: boolean

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)

sourceField: Field

sourceFieldName: SourceFieldNameT

to: ViewModel Class

Get the ViewModel this related field is to.

If to was defined as a function returning a Promise then you must call resolveViewModel and wait for the returned Promise to resolve before accessing this otherwise an error will be thrown

value: RelatedViewModelValueType[]

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)