addLocalRowIdsListener
The addLocalRowIdsListener
method registers a listener function with the Relationships
object that will be called whenever the local Row
Ids
in a Relationship
change.
addLocalRowIdsListener(
relationshipId: IdOrNull,
remoteRowId: IdOrNull,
listener: LocalRowIdsListener,
): string
Type | Description | |
---|---|---|
relationshipId | IdOrNull | The |
remoteRowId | IdOrNull | The |
listener | LocalRowIdsListener | The function that will be called whenever the local |
returns | string | A unique |
You can either listen to a single local Row
(by specifying the Relationship
Id
and local Row
Id
as the method's first two parameters), or changes to any local Row
(by providing a null
wildcards).
Both, either, or neither of the relationshipId
and remoteRowId
parameters can be wildcarded with null
. You can listen to a specific remote Row
in a specific Relationship
, any remote Row
in a specific Relationship
, a specific remote Row
in any Relationship
, or any remote Row
in any Relationship
.
The provided listener is a LocalRowIdsListener
function, and will be called with a reference to the Relationships
object, the Id
of the Relationship
, and the Id
of the remote Row
that had its local Row
objects change.
Examples
This example creates a Store
, a Relationships
object, and then registers a listener that responds to any changes to a specific remote Row
's local Row
objects.
import {createRelationships, createStore} from 'tinybase';
const store = createStore()
.setTable('pets', {
fido: {species: 'dog'},
felix: {species: 'cat'},
cujo: {species: 'dog'},
})
.setTable('species', {
wolf: {price: 10},
dog: {price: 5},
cat: {price: 4},
});
const relationships = createRelationships(store);
relationships.setRelationshipDefinition(
'petSpecies',
'pets',
'species',
'species',
);
const listenerId = relationships.addLocalRowIdsListener(
'petSpecies',
'dog',
(relationships) => {
console.log('petSpecies relationship (to dog) changed');
console.log(relationships.getLocalRowIds('petSpecies', 'dog'));
},
);
store.setRow('pets', 'toto', {species: 'dog'});
// -> 'petSpecies relationship (to dog) changed'
// -> ['fido', 'cujo', 'toto']
relationships.delListener(listenerId);
This example creates a Store
, a Relationships
object, and then registers a listener that responds to any changes to any remote Row
's local Row
objects.
import {createRelationships, createStore} from 'tinybase';
const store = createStore()
.setTable('pets', {
fido: {species: 'dog', color: 'brown'},
felix: {species: 'cat', color: 'black'},
cujo: {species: 'dog', color: 'brown'},
toto: {species: 'dog', color: 'grey'},
})
.setTable('species', {
wolf: {price: 10},
dog: {price: 5},
cat: {price: 4},
})
.setTable('color', {
brown: {discount: 0.1},
black: {discount: 0},
grey: {discount: 0.2},
});
const relationships = createRelationships(store)
.setRelationshipDefinition('petSpecies', 'pets', 'species', 'species')
.setRelationshipDefinition('petColor', 'pets', 'color', 'color');
const listenerId = relationships.addLocalRowIdsListener(
null,
null,
(relationships, relationshipId, remoteRowId) => {
console.log(
`${relationshipId} relationship (to ${remoteRowId}) changed`,
);
console.log(relationships.getLocalRowIds(relationshipId, remoteRowId));
},
);
store.setRow('pets', 'cujo', {species: 'wolf', color: 'grey'});
// -> 'petSpecies relationship (to dog) changed'
// -> ['fido', 'toto']
// -> 'petSpecies relationship (to wolf) changed'
// -> ['cujo']
// -> 'petColor relationship (to brown) changed'
// -> ['fido']
// -> 'petColor relationship (to grey) changed'
// -> ['toto', 'cujo']
relationships.delListener(listenerId);
Since
v1.0.0