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useResultRowCount

The useResultRowCount hook returns the count of the Row objects in the ResultTable of the given query, and registers a listener so that any changes to that result will cause a re-render.

useResultRowCount(
  queryId: string,
  queriesOrQueriesId?: QueriesOrQueriesId,
): number
TypeDescription
queryIdstring

The Id of the query.

queriesOrQueriesId?QueriesOrQueriesId

The Queries object to be accessed: omit for the default context Queries object, provide an Id for a named context Queries object, or provide an explicit reference. See the addResultRowCountListener method for more details.

returnsnumber

The number of ResultRow objects in the ResultTable.

A Provider component is used to wrap part of an application in a context, and it can contain a default Queries object or a set of Queries objects named by Id. The useResultRowCount hook lets you indicate which Queries object to get data for: omit the final optional final parameter for the default context Queries object, provide an Id for a named context Queries object, or provide a Queries object explicitly by reference.

When first rendered, this hook will create a listener so that changes to the count of ResultRow objects will cause a re-render. When the component containing this hook is unmounted, the listener will be automatically removed.

Examples

This example creates a Queries object outside the application, which is used in the useResultRowCount hook by reference. A change to the data in the query re-renders the component.

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

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(
  'dogColors',
  'pets',
  ({select, where}) => {
    select('color');
    where('species', 'dog');
  },
);
const App = () => <span>{useResultRowCount('dogColors', queries)}</span>;

const app = document.createElement('div');
createRoot(app).render(<App />);
console.log(app.innerHTML);
// -> '<span>2</span>'

store.setCell('pets', 'cujo', 'species', 'wolf');
console.log(app.innerHTML);
// -> '<span>1</span>'

This example creates a Provider context into which a default Queries object is provided. A component within it then uses the useResultRowCount hook.

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

const App = ({queries}) => (
  <Provider queries={queries}>
    <Pane />
  </Provider>
);
const Pane = () => <span>{useResultRowCount('dogColors')}</span>;

const queries = createQueries(
  createStore().setTable('pets', {
    fido: {species: 'dog', color: 'brown'},
    felix: {species: 'cat', color: 'black'},
    cujo: {species: 'dog', color: 'black'},
  }),
).setQueryDefinition('dogColors', 'pets', ({select, where}) => {
  select('color');
  where('species', 'dog');
});
const app = document.createElement('div');
createRoot(app).render(<App queries={queries} />);
console.log(app.innerHTML);
// -> '<span>2</span>'

This example creates a Provider context into which a Queries object is provided, named by Id. A component within it then uses the useResultRowCount hook.

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

const App = ({queries}) => (
  <Provider queriesById={{petQueries: queries}}>
    <Pane />
  </Provider>
);
const Pane = () => (
  <span>{useResultRowCount('dogColors', 'petQueries')}</span>
);

const queries = createQueries(
  createStore().setTable('pets', {
    fido: {species: 'dog', color: 'brown'},
    felix: {species: 'cat', color: 'black'},
    cujo: {species: 'dog', color: 'black'},
  }),
).setQueryDefinition('dogColors', 'pets', ({select, where}) => {
  select('color');
  where('species', 'dog');
});
const app = document.createElement('div');
createRoot(app).render(<App queries={queries} />);
console.log(app.innerHTML);
// -> '<span>2</span>'

Since

v4.1.0