A key value store that is transferred from the application on the server side to the application on the client side.

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class TransferState {
  isEmpty: boolean
  get<T>(key: StateKey<T>, defaultValue: T): T
  set<T>(key: StateKey<T>, value: T): void
  remove<T>(key: StateKey<T>): void
  hasKey<T>(key: StateKey<T>): boolean
  onSerialize<T>(key: StateKey<T>, callback: () => T): void
  toJson(): string
}

Provided in

• 'root'

Description

The TransferState is available as an injectable token. On the client, just inject this token using DI and use it, it will be lazily initialized. On the server it's already included if renderApplication function is used. Otherwise, import the ServerTransferStateModule module to make the TransferState available.

The values in the store are serialized/deserialized using JSON.stringify/JSON.parse. So only boolean, number, string, null and non-class objects will be serialized and deserialized in a non-lossy manner.

Properties

Property	Description
isEmpty: boolean	Read-Only Indicates whether the state is empty.

Methods

get()
Get the value corresponding to a key. Return defaultValue if key is not found.
get<T>(key: StateKey<T>, defaultValue: T): T Parameters key StateKey<T> defaultValue T Returns T

set()
Set the value corresponding to a key.
set<T>(key: StateKey<T>, value: T): void Parameters key StateKey<T> value T Returns void

remove()
Remove a key from the store.
remove<T>(key: StateKey<T>): void Parameters key StateKey<T> Returns void

hasKey()
Test whether a key exists in the store.
hasKey<T>(key: StateKey<T>): boolean Parameters key StateKey<T> Returns boolean

onSerialize()
Register a callback to provide the value for a key when toJson is called.
onSerialize<T>(key: StateKey<T>, callback: () => T): void Parameters key StateKey<T> callback () => T Returns void

toJson()
Serialize the current state of the store to JSON.
toJson(): string Parameters There are no parameters. Returns string