`addWillDelValueCallback`

The addWillDelValueCallback method registers a WillDelValueCallback that will be called before any Value is deleted from the Store.

addWillDelValueCallback(callback: WillDelValueCallback): Middleware

Type Description

	Type	Description
`callback`	`WillDelValueCallback`	The `WillDelValueCallback` to register.
returns	`Middleware`	A reference to the `Middleware` object, for chaining.

callback

WillDelValueCallback

The WillDelValueCallback to register.

returns

Middleware

A reference to the Middleware object, for chaining.

The callback returns true to allow the deletion or false to prevent it. Multiple callbacks can be registered and they are called sequentially. If any callback returns false, the deletion is prevented.

Example

This example registers a callback that prevents deleting the 'storeName' Value from the pet store.

import {createMiddleware, createStore} from 'tinybase';

const store = createStore();
const middleware = createMiddleware(store);

store.setValue('storeName', 'happy pets');

middleware.addWillDelValueCallback((valueId) => valueId !== 'storeName');

store.delValue('storeName');
console.log(store.getValue('storeName'));
// -> 'happy pets'

middleware.destroy();

Since

v8.0.0