1.8 KiB
The Realm JavaScript SDK supports querying based on a language inspired by NSPredicate.
The {@link Realm.Collection#filtered Collection.filtered()} method is used to query a Realm:
let contacts = realm.objects('Contact');
let friendsPage2 = contacts.filtered('type == "friend" AND name BEGINSWITH "B"');
It's possible to filter by linked or child objects with a keypath.
Example:
let johnsChildren = realm.Object('Contact').filtered('father.name == "John"');
Query strings can use numbered ($0, $1, ...) placeholders. The succeeding parameters contain the values.
Named placeholders are not yet supported.
Example:
let merlots = wines.filtered('variety == $0 && vintage <= $1', 'Merlot', maxYear);
Relational operators
You can use equality comparison on all property types:
== and !=
Furthermore, the following can be used on numerical types:
<, <=, >, >=
Example:
let oldContacts = realm.objects('Contact').filtered('age > 2');
Note that for boolean properties, you should test against the expected keyword.
Example:
let women = realm.objects('Contact').filtered('isMale == false');
String operators
For string properties, prefix, suffix, and substring queries are supported by using the BEGINSWITH, ENDSWITH, and CONTAINS operators.
For any string operation you can append [c] to the operator to make it case insensitive.
Example:
let peopleWhoseNameContainsA = realm.objects('Contact').filtered('name CONTAINS[c] "a"');
let Johns = realm.objects('Contact').filtered('name ==[c] "john"');
Composition
Use parentheses and the &&/AND and ||/OR operators to compose queries. You can negate a predicate with !/NOT.