`useHasRowListener`

The useHasRowListener hook registers a listener function with the Store that will be called when a Row is added to or removed from the Store.

useHasRowListener(
  tableId: IdOrNull,
  rowId: IdOrNull,
  listener: HasRowListener,
  listenerDeps?: DependencyList,
  mutator?: boolean,
  storeOrStoreId?: StoreOrStoreId,
): void

	Type	Description
`tableId`	`IdOrNull`	The `Id` of the `Table` to listen to, or `null` as a wildcard.
`rowId`	`IdOrNull`	The `Id` of the `Row` to listen to, or `null` as a wildcard.
`listener`	`HasRowListener`	The function that will be called whenever the matching `Row` is added or removed.
`listenerDeps?`	`DependencyList`	An optional array of dependencies for the `listener` function, which, if any change, result in the re-registration of the listener. This parameter defaults to an empty array.
`mutator?`	`boolean`	An optional boolean that indicates that the listener mutates `Store` data.
`storeOrStoreId?`	`StoreOrStoreId`	The `Store` to register the listener with: omit for the default context `Store`, provide an `Id` for a named context `Store`, or provide an explicit reference.
returns	`void`	This has no return value.

This hook is useful for situations where a component needs to register its own specific listener to do more than simply tracking the value (which is more easily done with the useHasRow hook).

You can either listen to a single Row being added or removed (by specifying the Table Id and Row Id, as the method's first two parameters) or changes to any Row (by providing null wildcards).

Both, either, or neither of the tableId and rowId parameters can be wildcarded with null. You can listen to a specific Row in a specific Table, any Row in a specific Table, a specific Row in any Table, or any Row in any Table.

Unlike the addHasRowListener method, which returns a listener Id and requires you to remove it manually, the useHasRowListener hook manages this lifecycle for you: when the listener changes (per its listenerDeps dependencies) or the component unmounts, the listener on the underlying Store will be deleted.

Example

This example uses the useHasRowListener hook to create a listener that is scoped to a single component. When the component is unmounted, the listener is removed from the Store.

import {Provider, useHasRowListener} from 'tinybase/ui-react';
import React from 'react';
import {createRoot} from 'react-dom/client';
import {createStore} from 'tinybase';

const App = ({store}) => (
  <Provider store={store}>
    <Pane />
  </Provider>
);
const Pane = () => {
  useHasRowListener('pets', 'fido', () =>
    console.log('Row existence changed'),
  );
  return <span>App</span>;
};

const store = createStore();
const app = document.createElement('div');
const root = createRoot(app);
root.render(<App store={store} />);
console.log(store.getListenerStats().hasRow);
// -> 1

store.setCell('pets', 'fido', 'color', 'walnut');
// -> 'Row existence changed'

root.unmount();
console.log(store.getListenerStats().hasRow);
// -> 0

Since

v4.4.0