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  • Find a Specific Object by Primary Key
  • Query an Object Type
  • Filter Queries
  • Sort Query Results

If you know the primary key for a given object, you can look it up directly with Realm.objectForPrimaryKey().

const myTask = realm.objectForPrimaryKey("Task", 12342245); // search for a realm object with a primary key that is an int.

To query for objects of a given type in a realm, pass the type name to Realm.objects().

Query operations return a collection of Realm objects that match the query as a Realm.Results object. A basic query matches all objects of a given type in a realm, but you can also apply a filter to the collection to find specific objects.

// Query realm for all instances of the "Task" type.
const tasks = realm.objects("Task");

A filter selects a subset of results based on the value(s) of one or more object properties. Realm lets you filter data using Realm Query Language, a string-based query language to constrain searches when retrieving objects from a realm.

To filter a query, call filtered() on the query results collection. Pass a Realm Query Language query as argument to filtered().

In the following example, we use the query engine's comparison operators to:

  • Find high priority tasks by comparing the value of the priority property value with a threshold number, above which priority can be considered high.

  • Find just-started or short-running tasks by seeing if the progressMinutes property falls within a certain range.

// retrieve the set of Task objects
const tasks = realm.objects("Task");
// filter for tasks with a high priority
const highPriorityTasks = tasks.filtered("priority > $0", 5);
// filter for tasks that have just-started or short-running progress
const lowProgressTasks = tasks.filtered(
"$0 <= progressMinutes && progressMinutes < $1",
1,
10
);
console.log(
`Number of high priority tasks: ${highPriorityTasks.length} \n`,
`Number of just-started or short-running tasks: ${lowProgressTasks.length}`
);

Tip

Filter on Related and Embedded Object Properties

To filter a query based on a property of an embedded object or a related object, use dot-notation as if it were in a regular, nested object.

A sort operation allows you to configure the order in which Realm returns queried objects. You can sort based on one or more properties of the objects in the results collection. Realm only guarantees a consistent order of results if you explicitly sort them.

To sort a query, call the sorted() method on the query results collection.

// retrieve the set of Task objects
const tasks = realm.objects("Task");
// Sort tasks by name in ascending order
const tasksByName = tasks.sorted("name");
// Sort tasks by name in descending order
const tasksByNameDescending = tasks.sorted("name", true);
// Sort tasks by priority in descending order and then by name alphabetically
const tasksByPriorityDescendingAndName = tasks.sorted([
["priority", true],
["name", false],
]);
// Sort dogs by dog's owner's name.
let dogsByOwnersName = realm.objects("Dog").sorted("owner.name");

Tip

Sort on Related and Embedded Object Properties

To sort a query based on a property of an embedded object or a related object, use dot-notation as if it were in a regular, nested object.

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