`useResultRowListener`

The useResultRowListener hook registers a listener function with a Queries object that will be called whenever data in a result Row changes.

useResultRowListener(
  queryId: IdOrNull,
  rowId: IdOrNull,
  listener: ResultRowListener,
  listenerDeps?: DependencyList,
  queriesOrQueriesId?: QueriesOrQueriesId,
): void

	Type	Description
`queryId`	`IdOrNull`	The `Id` of the query to listen to, or `null` as a wildcard.
`rowId`	`IdOrNull`	The `Id` of the result `Row` to listen to, or `null` as a wildcard.
`listener`	`ResultRowListener`	The function that will be called whenever data in the matching result `Row` changes.
`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.
`queriesOrQueriesId?`	`QueriesOrQueriesId`	The `Queries` object to register the listener with: omit for the default context `Queries` object, provide an `Id` for a named context `Queries` object, 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 useResultRow hook).

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

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

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

Example

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

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

const App = ({queries}) => (
  <Provider queries={queries}>
    <Pane />
  </Provider>
);
const Pane = () => {
  useResultRowListener('petColors', 'fido', () =>
    console.log('Result row changed'),
  );
  return <span>App</span>;
};

const store = createStore().setTable('pets', {
  fido: {species: 'dog', color: 'brown'},
  felix: {species: 'cat', color: 'black'},
  cujo: {species: 'dog', color: 'black'},
});
const queries = createQueries(store).setQueryDefinition(
  'petColors',
  'pets',
  ({select}) => select('color'),
);
const app = document.createElement('div');
const root = createRoot(app);
root.render(<App queries={queries} />);
console.log(queries.getListenerStats().row);
// -> 1

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

root.unmount();
console.log(queries.getListenerStats().row);
// -> 0

Since

v2.0.0