`useParamValue`

The useParamValue primitive returns the current value of a single parameter in a query.

useParamValue(
  queryId: MaybeAccessor<string>,
  paramId: MaybeAccessor<string>,
  queriesOrQueriesId?: MaybeAccessor<undefined | QueriesOrQueriesId>,
): Accessor<ParamValue | undefined>

	Type	Description
`queryId`	`MaybeAccessor<string>`	The `Id` of the query to get the parameter value from.
`paramId`	`MaybeAccessor<string>`	The `Id` of the parameter to get the value of.
`queriesOrQueriesId?`	`MaybeAccessor<undefined \| 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.
returns	`Accessor<ParamValue \| undefined>`	The value of the parameter, or undefined if it doesn't exist.

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 useParamValue primitive lets you indicate which Queries object to get data for: omit the 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 primitive will create a listener so that changes to the parameter value will cause an update. When the component containing this primitive is unmounted, the listener will be automatically removed.

Example

This example creates the TinyBase objects needed by the Solid primitive or component and calls it from within a reactive root.

import {createRoot} from 'solid-js';
import {
  createCheckpoints,
  createIndexes,
  createMetrics,
  createQueries,
  createRelationships,
  createStore,
} from 'tinybase';
import {useParamValue} from 'tinybase/ui-solid';

createRoot((dispose) => {
  const store = createStore()
    .setTables({
      pets: {
        fido: {species: 'dog', color: 'brown', next: 'felix'},
        felix: {species: 'cat', color: 'black'},
      },
      species: {dog: {price: 5}, cat: {price: 4}},
    })
    .setValues({open: true});
  const metrics = createMetrics(store).setMetricDefinition(
    'highestPrice',
    'species',
    'max',
    'price',
  );
  const indexes = createIndexes(store).setIndexDefinition(
    'bySpecies',
    'pets',
    'species',
  );
  const relationships = createRelationships(store)
    .setRelationshipDefinition('petSpecies', 'pets', 'species', 'species')
    .setRelationshipDefinition('nextPet', 'pets', 'pets', 'next');
  const queries = createQueries(store).setQueryDefinition(
    'petColors',
    'pets',
    ({select, where, param}) => {
      select('color');
      where((getCell) => getCell('species') == param('species'));
    },
    {species: 'dog'},
  );
  const checkpoints = createCheckpoints(store);
  store.setCell('pets', 'fido', 'color', 'walnut');
  checkpoints.setCheckpoint('updated color');
  metrics.getMetric('highestPrice');
  indexes.getSliceIds('bySpecies');
  relationships.getRemoteRowId('petSpecies', 'fido');
  queries.getResultRowIds('petColors');
  useParamValue('petColors', 'species', queries);
  dispose();
});

Since

v8.3.0