Save signal state (@ngrx/signals) to localStorage/sessionStorage and restore the state on page load.
npm install @larscom/ngrx-signals-storage@larscom/ngrx-signals-storage depends on @ngrx/signals and Angular
Import withStorage function and place it after the withState function.
import { withStorage } from '@larscom/ngrx-signals-storage'
import { withState, signalStore } from '@ngrx/signals'
export const CounterStore = signalStore(
withState({
count: 0
}),
// state will be saved to sessionStorage under the key: 'myKey'
// optional config can be passed as 3th argument
withStorage('myKey', sessionStorage, { saveIf: ({ count }) => count > 0 })
)export interface Config<T> {
/**
* These keys will not get saved to storage
*/
excludeKeys: Array<keyof T>
/**
* Serializer for the state, by default it uses `JSON.stringify()`
* @param state the last state known before it gets saved to storage
*/
serialize: (state: T) => string
/**
* Deserializer for the state, by default it uses `JSON.parse()`
* @param state the last state known from the storage location
*/
deserialize: (state: string) => T
/**
* Save to storage will only occur when this function returns true
* @param state the last state known before it gets saved to storage
*/
saveIf: (state: T) => boolean
/**
* Function that gets executed on a storage error (get/set)
* @param error the error that occurred
*/
error: (error: any) => void
}Whenever you get errors this is most likely due to serialization / deserialization of the state.
Objects like Map and Set are not serializable so you might need to implement your own serialize / deserialize function.
Lets say you have a Set in your store, then you need a custom serialize / deserialize function to convert from Set to Array (serialize) and from Array to Set (deserialize)
export const MyStore = signalStore(
withState({
mySet: new Set([1, 1, 3, 3])
}),
withStorage('myKey', sessionStorage, {
serialize: (state) => JSON.stringify({ ...state, mySet: Array.from(state.mySet) }),
deserialize: (stateString) => {
const state = JSON.parse(stateString)
return {
...state,
mySet: new Set(state.mySet)
}
}
})
)