Realm Query Language

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Realm Query Language (RQL) is a string-based query language to constrain searches when retrieving objects from a realm. SDK-specific methods pass queries to the Realm query engine, which retrieves matching objects from the realm. Realm Query Language syntax is based on NSPredicate.

Queries evaluate a predicate for every object in the collection being queried. If the predicate resolves to true, the results collection includes the object.

You can use Realm Query Language in most Realm SDKs with your SDK's filter or query methods. The Swift SDK is the exception, as it uses the NSPredicate query API. Some SDKs also support idiomatic APIs for querying realms in their language.

Query with Realm SDKs

For further reading on SDK-specific methods for querying realms, see the documentation for your SDK:

Filter & Sort Results - Flutter SDK

Filter Data - Kotlin SDK

Query Engine - .NET SDK

The C++ SDK currently implements only a subset of RQL. For examples querying Realm in the C++ SDK, refer to:

Filter Data - C++ SDK

Note

Swift SDK does not support Realm Query Language

The Swift SDK does not support querying with Realm Query Language. You can instead use NSPredicate to query Realm. For examples of querying Realm in the Swift SDK, refer to Filter Data - Swift SDK.

You can also use Realm Query Language to browse for data in Realm Studio. Realm Studio is a visual tool to view, edit, and design Realm files.

Examples on This Page

Many of the examples in this page use a simple data set for a to-do list app. The two Realm object types are Project and Item.

An Item has a name, assignee's name, and completed flag. There is also an arbitrary number for priority (higher is more important) and a count of minutes spent working on it.
A Project has zero or more Items and an optional quota for minimum number of to-do items expected to be completed.

See the schema for these two classes, Project and Item, below:

public class Item extends RealmObject {
  ObjectId id = new ObjectId();
  String name;
  Boolean isComplete = false;
  String assignee;
  Integer priority = 0;
  Integer progressMinutes = 0;
  @LinkingObjects("items")
  final RealmResults<Project> projects = null;
}
public class Project extends RealmObject {
  ObjectId id = new ObjectId();
  String name;
  RealmList<Item> items;
  Integer quota = null;
}

open class Item(): RealmObject() {
  var id: ObjectId = new ObjectId()
  @FullText
  lateinit var name: String
  var isComplete: Boolean = false
  var assignee: String? = null
  var priority: Int = 0
  var progressMinutes: Int = 0
}
open class Project(): RealmObject() {
  var id: ObjectId = new ObjectId()
  lateinit var name: String
  lateinit var items: RealmList<Item>
  var quota: Int? = null
}

public class Item : RealmObject
{
    [PrimaryKey]
    [MapTo("_id")]
    public ObjectId Id { get; set; } = ObjectId.GenerateNewId();
    [MapTo("name")]
    [Indexed(IndexType.FullText)]
    public string Name { get; set; }
    [MapTo("isComplete")]
    public bool IsComplete { get; set; } = false;
    [MapTo("assignee")]
    public string Assignee { get; set; }
    [MapTo("priority")]
    public int Priority { get; set; } = 0;
    [MapTo("progressMinutes")]
    public int ProgressMinutes { get; set; } = 0;
    [MapTo("projects")]
    [Backlink(nameof(Project.Items))]
    public IQueryable<Project> Projects { get; }
}
public class Project : RealmObject
{
    [PrimaryKey]
    [MapTo("_id")]
    public ObjectId Id { get; set; } = ObjectId.GenerateNewId();
    [MapTo("name")]
    public string Name { get; set; }
    [MapTo("items")]
    public IList<Item> Items { get; }
    [MapTo("quota")]
    public int Quota { get; set; }
}

const ItemModel = {
  name: "Item",
  properties: {
    id: "objectId",
    name: {type: "string", indexed: "full-text"},
    isComplete: { type: "bool", default: false },
    assignee: "string?",
    priority: {
      type: "int",
      default: 0,
    },
    progressMinutes: {
      type: "int",
      default: 0,
    },
    projects: {
      type: "linkingObjects",
      objectType: "Project",
      property: "items",
    },
  },
  primaryKey: "id",
};
const ProjectModel = {
  name: "Project",
  properties: {
    id: "objectId",
    name: "string",
    items: "Item[]",
    quota: "int?",
  },
  primaryKey: "id",
};

const ItemModel = {
  name: "Item",
  properties: {
    id: "objectId",
    name: {type: "string", indexed: "full-text"},
    isComplete: { type: "bool", default: false },
    assignee: "string?",
    priority: {
      type: "int",
      default: 0,
    },
    progressMinutes: {
      type: "int",
      default: 0,
    },
    projects: {
      type: "linkingObjects",
      objectType: "Project",
      property: "items",
    },
  },
  primaryKey: "id",
};
const ProjectModel = {
  name: "Project",
  properties: {
    id: "objectId",
    name: "string",
    items: "Item[]",
    quota: "int?",
  },
  primaryKey: "id",
};

class Item(): RealmObject {
    @PrimaryKey
    var _id: ObjectId = ObjectId()
    @FullText
    var name: String = ""
    var isComplete: Boolean = false
    var assignee: String? = null
    var priority: Int = 0
    var progressMinutes: Int = 0
}
class Project(): RealmObject {
    @PrimaryKey
    var _id: ObjectId = ObjectId()
    var name: String = ""
    var items: RealmList<Item> = realmListOf<Item>()
    var quota: Int? = null
}

part 'models.realm.dart';
@RealmModel()
class _Project {
  @MapTo("_id")
  @PrimaryKey()
  late ObjectId id;
  late String name;
  late List<_Item> items;
  int? quota;
}
@RealmModel()
class _Item {
  @MapTo("_id")
  @PrimaryKey()
  late ObjectId id;
  @Indexed(RealmIndexType.fullText)
  late String name;
  bool isComplete = false;
  String? assignee;
  int priority = 0;
  int progressMinutes = 0;
}

Expressions

Filters consist of expressions in a predicate. An expression consists of one of the following:

The name of a property of the object currently being evaluated.
An operator and up to two argument expression(s). For example, in the expression A + B, the entirety of A + B is an expression, but A and B are also argument expressions to the operator +.
A value, such as a string ('hello') or a number (5).

"progressMinutes > 1 AND assignee == $0", "Ali"

Parameterized Queries

Create parameterized queries to interpolate variables into prepared Realm Query Language statements. The syntax for interpolated variables is $<int>, starting at 0. Pass the positional arguments as additional arguments to Realm SDK methods that use Realm Query Language.

Include just one parameter with $0.

"progressMinutes > 1 AND assignee == $0", "Ali"

Include multiple parameters with ascending integers starting at $0.

"progressMinutes > $0 AND assignee == $1", 1, "Alex"

Query Formats

The following table shows how a query should be formatted when serialized and parameterized for the following data types:

Type	Parameterized Example	Serialized Example	Note
Boolean	"setting == $0", false	"setting == false"	`true` or `false` values.
String	"name == $0", "George"	"name == 'George'"	Applies to `string` and `char` data type.
Number	"age > $0", 5.50	"age > 5.50"	Applies to `int`, `short`, `long`, `double`, `Decimal128`, and `float` data types.
Date	"date < $0", dateObject	"date < 2021-02-20@17:30:15:0"	For parameterized date queries, you must pass in a date object. For serialized date queries, you can represented the date in the following formats: As an explicit date and time- YYYY-MM-DD@HH:mm:ss:nn (year-month-day@hours:minutes:seconds:nanoseconds) As a `datetime` relative to the Unix epoch- Ts:n (T, designates the start of the time; `s`, seconds; `n`, nanoseconds) Parameterized `Date` object
ObjectID	"_id == $0", oidValue	"_id == oid(507f1f77bcf86cd799439011)"	For parameterized ObjectId queries, you must pass in an ObjectId. For serialized ObjectId queries, the string representation is `oid(<ObjectId String>)`.
UUID	"id == $0", uuidValue	"id == uuid(d1b186e1-e9e0-4768-a1a7-c492519d47ee)"	For parameterized UUID queries, you must pass in a UUID. For serialized UUID queries, the string representation is `uuid(<UUID String>)`.
Binary	"value == $0", "binary"	"value == 'binary'"	For ASCII characters, RQL serializes the binary value like a string, with quotes. For non-printable characters, RQL serializes the binary to a base 64 value.
List	"ANY items.name == {$0, $1}", "milk", "bread"	"ANY items.name == {'milk', 'bread'}"	Applies for list, collections, and sets. A parameterized value should be used for each member of the list.
RealmObject	"ANY items == $0", obj("Item", oid(6489f036f7bd0546377303ab))	"ANY items == obj('Item', oid(6489f036f7bd0546377303ab))"	To pass in a RealmObject, you need the class and primary key of the object.

Dot Notation

When referring to an object property, you can use dot notation to refer to child properties of that object. You can even refer to the properties of embedded objects and relationships with dot notation.

For example, consider a query on an object with a workplace property that refers to a Workplace object. The Workplace object has an embedded object property, address. You can chain dot notations to refer to the zipcode property of that address:

"workplace.address.zipcode == 10019"

Nil Type

Realm Query Language include the nil type to represent a null pointer. You can either reference nil directly in your queries or with a parameterized query. If you're using a parameterized query, each SDK maps its respective null pointer to nil.

"assignee == nil"

// comparison to language null pointer
"assignee == $0", null

Comparison Operators

The most straightforward operation in a search is to compare values.

Important

Types Must Match

The type on both sides of the operator must be equivalent. For example, comparing an ObjectId with string will result in a precondition failure with a message like:

"Expected object of type object id for property 'id' on object of type
'User', but received: 11223344556677889900aabb (Invalid value)"

You can compare any numeric type with any other numeric type, including decimal, float, and Decimal128.

Operator	Description
`BETWEEN {number1, number2}`	Evaluates to `true` if the left-hand numerical or date expression is between or equal to the right-hand range. For dates, this evaluates to `true` if the left-hand date is within the right-hand date range.
`==`, `=`	Evaluates to `true` if the left-hand expression is equal to the right-hand expression.
`>`	Evaluates to `true` if the left-hand numerical or date expression is greater than the right-hand numerical or date expression. For dates, this evaluates to `true` if the left-hand date is later than the right-hand date.
`>=`	Evaluates to `true` if the left-hand numerical or date expression is greater than or equal to the right-hand numerical or date expression. For dates, this evaluates to `true` if the left-hand date is later than or the same as the right-hand date.
`IN`	Evaluates to `true` if the left-hand expression is in the right-hand list. This is equivalent to and used as a shorthand for `== ANY`.
`<`	Evaluates to `true` if the left-hand numerical or date expression is less than the right-hand numerical or date expression. For dates, this evaluates to `true` if the left-hand date is earlier than the right-hand date.
`<=`	Evaluates to `true` if the left-hand numeric expression is less than or equal to the right-hand numeric expression. For dates, this evaluates to `true` if the left-hand date is earlier than or the same as the right-hand date.
`!=`, `<>`	Evaluates to `true` if the left-hand expression is not equal to the right-hand expression.

Example

The following example uses Realm Query Language's comparison operators to:

Find high priority to-do items by comparing the value of the priority property value with a threshold number, above which priority can be considered high.
Find long-running to-do items by seeing if the progressMinutes property is at or above a certain value.
Find unassigned to-do items by finding items where the assignee property is equal to null.
Find to-do items within a certain time range by finding items where the progressMinutes property is between two numbers.
Find to-do items with a certain amount of progressMinutes from the given list.

  // Find high priority to-do items by comparing the value of the ``priority``
  // property value with a threshold number, above which priority can be considered high.
  "priority > $0", 5
  // Find long-running to-do items by seeing if the progressMinutes property is at or above a certain value.
  "progressMinutes > $0", 120
  // Find unassigned to-do items by finding items where the assignee property is equal to null.
  "assignee == $0", null
  // Find to-do items within a certain time range by finding items 
  // where the progressMinutes property is between two numbers.
  "progressMinutes BETWEEN { $0 , $1 }", 30, 60
  // Find to-do items with a certain amount of progressMinutes from the given list.
  "progressMinutes IN { $0, $1, $2, $3, $4, $5 }", 10, 20, 30, 40, 50, 60

Logical Operators

Make compound predicates using logical operators.

Operator	Description
`AND` `&&`	Evaluates to `true` if both left-hand and right-hand expressions are `true`.
`NOT` `!`	Negates the result of the given expression.
`OR` `\|\|`	Evaluates to `true` if either expression returns `true`.

Example

We can use the query language's logical operators to find all of Ali's completed to-do items. That is, we find all items where the assignee property value is equal to 'Ali' AND the isComplete property value is true:

"assignee == $0 AND isComplete == $1", "Ali", true

String Operators

Compare string values using these string operators. Regex-like wildcards allow more flexibility in search.

Note

You can use the following modifiers with the string operators:

[c] for case insensitivity.
```
"name CONTAINS[c] $0", 'a'
```

Operator	Description
`BEGINSWITH`	Evaluates to `true` if the left-hand string expression begins with the right-hand string expression. This is similar to `contains`, but only matches if the right-hand string expression is found at the beginning of the left-hand string expression.
`CONTAINS`	Evaluates to `true` if the right-hand string expression is found anywhere in the left-hand string expression.
`ENDSWITH`	Evaluates to `true` if the left-hand string expression ends with the right-hand string expression. This is similar to `contains`, but only matches if the left-hand string expression is found at the very end of the right-hand string expression.
`LIKE`	Evaluates to `true` if the left-hand string expression matches the right-hand string wildcard string expression. A wildcard string expression is a string that uses normal characters with two special wildcard characters: The `*` wildcard matches zero or more of any character The `?` wildcard matches any character. For example, the wildcard string "d?g" matches "dog", "dig", and "dug", but not "ding", "dg", or "a dog".
`==`, `=`	Evaluates to `true` if the left-hand string is lexicographically equal to the right-hand string.
`!=`, `<>`	Evaluates to `true` if the left-hand string is not lexicographically equal to the right-hand string.

Example

We use the query engine's string operators to find:

Projects with a name starting with the letter 'e'
Projects with names that contain 'ie'

  "name BEGINSWITH[c] $0", 'e'
  "name CONTAINS $0", 'ie'

ObjectId and UUID Operators

Query BSON ObjectIds and UUIDs. These data types are often used as primary keys.

To query with ObjectIds, use a parameterized query. Pass the ObjectId or UUID you're querying against as the argument.

"_id == $0", oidValue

You can also put a string representation of the ObjectId you're evaluating in oid(<ObjectId String>).

"_id == oid(6001c033600510df3bbfd864)"

To query with UUIDs, put a string representation of the UUID you're evaluating in uuid(<UUID String>).

"id == uuid(d1b186e1-e9e0-4768-a1a7-c492519d47ee)"

Operator	Description
`==`, `=`	Evaluates to `true` if the left-hand value is equal to the right-hand value.
`!=`, `<>`	Evaluates to `true` if the left-hand value is not equal to the right-hand value.

Arithmetic Operators

Perform basic arithmetic in one side of a RQL expression when evaluating numeric data types.

  "2 * priority > 6"
  // Is equivalent to
  "priority >= 2 * (2 - 1) + 2"

You can also use multiple object properties together in a mathematic operation.

"progressMinutes * priority == 90"

Operator	Description
`*`	Multiplication.
`/`	Division.
`+`	Addition.
`-`	Subtraction.
`()`	Group expressions together.

Type Operator

Check the type of a property using the @type operator. You can only use the type operator with mixed types and dictionaries.

Evaluate the property against a string representation of the data type name. Refer to SDK documentation on the mapping from the SDK language's data types to Realm data types.

Operator	Description
`@type`	Check if type of a property is the property name as a string. Use `==` and `!=` to compare equality.

  "mixedType.@type == 'string'"
  "mixedType.@type == 'bool'"

Dictionary Operators

Compare dictionary values using these dictionary operators.

Operator	Description
`@values`	Returns objects that have the value specified in the right-hand expression.
`@keys`	Returns objects that have the key specified in the right-hand expression.
`@size`, `@count`	The number of elements in a dictionary.
`Dictionary['key']`	Access the value at a key of a dictionary.
`ALL \| ANY \| NONE <property>.@type`	Checks if the dictionary contains properties of certain type.

You can also use dictionary operators in combination with comparison operators to filter objects based on dictionary keys and values. The following examples show some ways to use dictionary operators with comparison operators. All examples query a collection of Realm objects with a dictionary property named dict.

Example

The following examples use various dictionary operators.

  // Evaluates if there is a dictionary key with the name 'foo'
  "ANY dict.@keys == $0", 'foo'
  // Evaluates if there is a dictionary key with key 'foo' and value 'bar
  "dict['foo'] == $0", 'bar'
  // Evaluates if there is greater than one key-value pair in the dictionary
  "dict.@count > $0", 1
  // Evaluates if dictionary has property of type 'string'
  "ANY dict.@type == 'string'"
  // Evaluates if all the dictionary's values are integers
  "ALL dict.@type == 'bool'"
  // Evaluates if dictionary does not have any values of type int
  "NONE dict.@type == 'double'"
  // ANY is implied.
  "dict.@type == 'string'"

Date Operators

Query date types in a realm.

Generally, you should use a parameterized query to pass a date data type from the SDK language you are using to a query.

"timeCompleted < $0", someDate

You can also specify dates in the following two ways:

As a specific date (in UTC)- YYYY-MM-DD@HH:mm:ss:nnnnnnnnnn (year-month-day@hours:minutes:seconds:nanoseconds), UTC. You can also use T instead of @ to separate the date from the time.
As a time in seconds since the Unix epoch- Ts:n, where T designates the start of the time, s is the number of seconds, and n is the number of nanoseconds.

Date supports comparison operators.

Example

The following example shows how to use a parameterized query with a date object:

var date = new Date("2021-02-20@17:30:15:0");
  "timeCompleted > $0", date

Aggregate Operators

Apply an aggregate operator to a collection property of a Realm object. Aggregate operators traverse a collection and reduce it to a single value.

Operator	Description
`@avg`	Evaluates to the average value of a given numerical property across a collection. If any values are `null`, they are not counted in the result.
`@count`	Evaluates to the number of objects in the given collection.
`@max`	Evaluates to the highest value of a given numerical property across a collection. `null` values are ignored.
`@min`	Evaluates to the lowest value of a given numerical property across a collection. `null` values are ignored.
`@sum`	Evaluates to the sum of a given numerical property across a collection, excluding `null` values.

Example

These examples all query for projects containing to-do items that meet this criteria:

Projects with average item priority above 5.
Projects with an item whose priority is less than 5.
Projects with an item whose priority is greater than 5.
Projects with more than 5 items.
Projects with long-running items.

var priorityNum = 5;
  "items.@avg.priority > $0", priorityNum
  "items.@max.priority < $0", priorityNum
  "items.@min.priority > $0", priorityNum
  "items.@count > $0", 5
  "items.@sum.progressMinutes > $0", 100

Collection Operators

A collection operator lets you query list properties within a collection of objects. Collection operators filter a collection by applying a predicate to every element of a given list property of the object. If the predicate returns true, the object is included in the output collection.

Operator	Description
`ALL`	Returns objects where the predicate evaluates to `true` for all objects in the collection.
`ANY`, `SOME`	Returns objects where the predicate evaluates to `true` for any objects in the collection.
`NONE`	Returns objects where the predicate evaluates to false for all objects in the collection.

Example

This example uses collection operators to find projects that contain to-do items matching certain criteria:

  // Projects with no complete items.
  "NONE items.isComplete == $0", true
  // Projects that contain a item with priority 10
  "ANY items.priority == $0", 10
  // Projects that only contain completed items
  "ALL items.isComplete == $0", true
  // Projects with at least one item assigned to either Alex or Ali
  "ANY items.assignee IN { $0 , $1 }", "Alex", "Ali"
  // Projects with no items assigned to either Alex or Ali
  "NONE items.assignee IN { $0 , $1 }", "Alex", "Ali"

List Comparisons

You can use comparison operators and collection operators to filter based on lists of data.

You can compare any type of valid list. This includes:

collections of Realm objects, which let you filter against other data in the realm.
```
"oid(631a072f75120729dc9223d9) IN items.id"
```
lists defined directly in the query, which let you filter against static data. You define static lists as a comma-separated list of literal values enclosed in opening ({) and closing (}) braces.
```
"priority IN {0, 1, 2}"
```

native list objects passed in a parameterized expression, which let you pass application data directly to your queries.

const ids = [
  new BSON.ObjectId("631a072f75120729dc9223d9"),
  new BSON.ObjectId("631a0737c98f89f5b81cd24d"),
  new BSON.ObjectId("631a073c833a34ade21db2b2"),
];
const parameterizedQuery = realm.objects("Item").filtered("id IN $0", ids);

If you do not define a collection operator, a list expression defaults to the ANY operator.

Example

These two list queries are equivalent:

age == ANY {18, 21}
age == {18, 21}

Both of these queries return objects with an age property equal to either 18 or 21. You could also do the opposite by returning objects only if the age is not equal to either 18 or 21:

age == NONE {18, 21}

The following table includes examples that illustrate how collection operators interact with lists and comparison operators:

Expression	Match?	Reason
`ANY {1, 2, 3} > ALL {1, 2}`	true	A value on the left (3) is greater than some value on the right (both 1 and 2)
`ANY {1, 2, 3} == NONE {1, 2}`	true	3 does not match either of 1 or 2
`ANY {4, 8} == ANY {5, 9, 11}`	false	Neither 4 nor 8 matches any value on the right (5, 9 or 11)
`ANY {1, 2, 7} <= NONE {1, 2}`	true	A value on the left (7) is not less than or equal to both 1 and 2
`ALL {1, 2} IN ANY {1, 2, 3}`	true	Every value on the left (1 and 2) is equal to 1, 2 or 3
`ALL {3, 1, 4, 3} == NONE {1, 2}`	false	1 matches a value in the NONE list (1 or 2)
`ALL {} in ALL {1, 2}`	true	An empty list matches all lists
`NONE {1, 2, 3, 12} > ALL {5, 9, 11}`	false	12 is bigger than all values on the right (5, 9, and 11)
`NONE {4, 8} > ALL {5, 9, 11}`	true	4 and 8 are both less than some value on the right (5, 9, or 11)
`NONE {0, 1} < NONE {1, 2}`	true	0 and 1 are both less than none of 1 and 2

Full Text Search

You can use RQL to query on properties that have a full-text search (FTS) annotation. FTS supports boolean match word searches, rather than searches for relevance. For information on enabling FTS on a property, see the FTS documentation for your SDK:

Flutter SDK
Kotlin SDK
.NET SDK
Node.js SDK
React Native SDK
Swift SDK does not yet support Full-Text Search.

To query these properties, use the TEXT predicate in your query.

You can search for entire words or phrases, or limit your results with the following characters:

Exclude results for a word by placing the - character in front of the word.
Specify prefixes by placing the * character at the end of a prefix. Suffix searching is not currently supported.

In the following example, we query the Item.name property:

    // Filter for items with 'write' in the name
    "name TEXT $0", "write"
    // Find items with 'write' but not 'tests' using '-'
    "name TEXT $0", "write -tests"
    // Find items starting with 'wri-' using '*'
    "name TEXT $0", "wri*"

Full-Text Search Tokenizer Details

Full-Text Search (FTS) indexes support:

Tokens are diacritics- and case-insensitive.
Tokens can only consist of characters from ASCII and the Latin-1 supplement (western languages). All other characters are considered whitespace.
Words split by a hyphen (-) are split into two tokens. For example, full-text splits into full and text.

Geospatial Queries

You can query against geospatial data using the geoWithin operator. The geoWithin operator takes the latitude/longitude pair in a custom embedded object's coordinates property and a geospatial shape. The operator checks whether the cordinates point is contained within the geospatial shape.

The following geospatial shapes are supported for querying:

GeoCircle
GeoBox
GeoPolygon

To query geospatial data:

Create an object with a property containing the embedded geospatial data.
Define the geospatial shape to set the boundary for the query.
Query using the geoWithin RQL operator.

In the following query, we are checking that the coordinates of the embeddeded location property are contained within the GeoCircle shape, smallCircle:

"location geoWithin $0", smallCircle

For more information on defining geospatial shapes and objects with embedded geospatial data, see the geospatial documentation for your SDK:

Backlink Queries

A backlink is an inverse relationship link that lets you look up objects that reference another object. Backlinks use the to-one and to-many relationships defined in your object schemas but reverse the direction. Every relationship that you define in your schema implicitly has a corresponding backlink.

You can access backlinks in queries using the @links.<ObjectType>.<PropertyName> syntax, where <ObjectType> and <PropertyName> refer to a specific property on an object type that references the queried object type.

// Find items that belong to a project with a quota greater than 10 (@links)
"@links.Project.items.quota > 10"

You can also define a linkingObjects property to explicitly include the backlink in your data model. This lets you reference the backlink through an assigned property name using standard dot notation.

// Find items that belong to a project with a quota greater than 10 (LinkingObjects)
"projects.quota > 10"

The result of a backlink is treated like a collection and supports collection operators.

  // Find items where any project that references the item has a quota greater than 0
  "ANY @links.Project.items.quota > 0"
  // Find items where all projects that reference the item have a quota greater than 0
  "ALL @links.Project.items.quota > 0"

You can use aggregate operators on the backlink collection.

  // Find items that are referenced by multiple projects
  "projects.@count > 1"
  // Find items that are not referenced by any project
  "@links.Project.items.@count == 0"
  // Find items that belong to a project where the average item has
  // been worked on for at least 5 minutes
  "@links.Project.items.items.@avg.progressMinutes > 10"

You can query the count of all relationships that point to an object by using the @count operator directly on @links.

// Find items that are not referenced by another object of any type
"@links.@count == 0"

Subqueries

Iterate through list properties with another query using the SUBQUERY() predicate function.

Subqueries are useful for the following scenarios:

Matching each object in a list property on multiple conditions
Counting the number of objects that match a subquery

SUBQUERY() has the following structure:

SUBQUERY(<collection>, <variableName>, <predicate>)

collection: The name of the property to iterate through
variableName: A variable name of the element to use in the subquery
predicate: The subquery predicate. Use the variable specified by variableName to refer to the currently-iterated element.

A subquery iterates through the given collection and checks the given predicate against each object in the collection. The predicate can refer to the current iterated object with the variable name passed to SUBQUERY().

A subquery expression resolves to a list of objects. Realm only supports the @count aggregate operator on the result of a subquery. This allows you to count how many objects in the subquery input collection matched the predicate.

You can use the count of the subquery result as you would any other number in a valid expression. In particular, you can compare the count with the number 0 to return all matching objects.

Example

The following example shows two subquery filters on a collection of projects.

  // Returns projects with items that have not been completed
  // by a user named Alex.
  "SUBQUERY(items, $item, $item.isComplete == false AND $item.assignee == 'Alex').@count > 0"
  // Returns the projects where the number of completed items is
  // greater than or equal to the value of a project's `quota` property.
  "SUBQUERY(items, $item, $item.isComplete == true).@count >= quota"

Sort, Distinct & Limit

Sort and limit the results collection of your query using additional operators.

Operator	Description
`SORT`	Specify the name of the property to compare, and whether to sort by ascending (`ASC`) or descending (`DESC`) order. If you specify multiple SORT fields, you must specify sort order for each field. With multiple sort fields, the query sorts by the first field, and then the second. For example, if you `SORT (priority DESC, name DESC)`, the query returns sorted by priority, and then by name when priority value is the same.
`DISTINCT`	Specify a name of the property to compare. Remove duplicates for that property in the results collection. If you specify multiple DISTINCT fields, the query removes duplicates by the first field, and then the second. For example, if you `DISTINCT (name, assignee)`, the query only removes duplicates where the values of both properties are the same.
`LIMIT`	Limit the results collection to the specified number.

Example

Use the query engine's sort, distinct, and limit operators to find to-do items where the assignee is Ali:

Sorted by priority in descending order
Enforcing uniqueness by name
Limiting the results to 5 items

"assignee == 'Ali' SORT(priority DESC) DISTINCT(name) LIMIT(5)"

Flexible Sync RQL Limitations

Indexed Queryable Fields Subscription Requirements

Adding an indexed queryable field to your App can improve performance for simple queries on data that is strongly partitioned. For example, an app where queries strongly map data to a device, store, or user, such as user_id == $0, “641374b03725038381d2e1fb”, is a good candidate for an indexed queryable field. However, an indexed queryable field has specific requirements for use in a query subscription:

The indexed queryable field must be used in every subscription query. It cannot be missing from the query.
The indexed queryable field must use an == or IN comparison against a constant at least once in the subscription query. For example, user_id == $0, "641374b03725038381d2e1fb" or store_id IN $0, {1,2,3}.

You can optionally include an AND comparison as long as the indexed queryable field is directly compared against a constant using == or IN at least once. For example, store_id IN {1,2,3} AND region=="Northeast" or store_id == 1 AND (active_promotions < 5 OR num_employees < 10).

Invalid Flexible Sync queries on an indexed queryable field include queries where:

The indexed queryable field does not use AND with the rest of the query. For example store_id IN {1,2,3} OR region=="Northeast" is invalid because it uses OR instead of AND. Similarly, store_id == 1 AND active_promotions < 5 OR num_employees < 10 is invalid because the AND only applies to the term next to it, not the entire query.
The indexed queryable field is not used in an equality operator. For example store_id > 2 AND region=="Northeast" is invalid because it uses only the > operator with the indexed queryable field and does not have an equality comparison.
The query is missing the indexed queryable field entirely. For example, region=="Northeast or truepredicate are invalid because they do not contain the indexed queryable field.

Unsupported Query Operators in Flexible Sync

Flexible Sync has some limitations when using RQL operators. When you write the query subscription that determines which data to sync, the server does not support these query operators. However, you can still use the full range of RQL features to query the synced data set in the client application.

Operator Type	Unsupported Operators
Aggregate Operators	`@avg`, `@count`, `@max`, `@min`, `@sum`
Query Suffixes	`DISTINCT`, `SORT`, `LIMIT`

Case insensitive queries ([c]) cannot use indexes effectively. As a result, case insensitive queries are not recommended, since they could lead to performance problems.

Flexible Sync only supports @count for array fields.

List Queries

Flexible Sync supports querying lists using the IN operator.

You can query a list of constants to see if it contains the value of a queryable field:

// Query a constant list for a queryable field value
"priority IN { 1, 2, 3 }"

If a queryable field has an array value, you can query to see if it contains a constant value:

// Query an array-valued queryable field for a constant value
"'comedy' IN genres"

Warning

You cannot compare two lists with each other in a Flexible Sync query. Note that this is valid Realm Query Language syntax outside of Flexible Sync queries.

// Invalid Flexible Sync query. Do not do this!
"{'comedy', 'horror', 'suspense'} IN genres"
// Another invalid Flexible Sync query. Do not do this!
"ANY {'comedy', 'horror', 'suspense'} != ANY genres"

Embedded or Linked Objects

Flexible Sync does not support querying on properties in Embedded Objects or links. For example, obj1.field == "foo".

Back

Modify Schema

Example Projects

Realm Query Language.leafygreen-ui-m0pgrr{-webkit-align-self:center;-ms-flex-item-align:center;align-self:center;padding:0 10px;visibility:hidden;}.leafygreen-ui-a30zj9{color:#889397;vertical-align:middle;margin-top:-2px;}.css-1l4s55v{margin-top:-175px;position:absolute;padding-bottom:2px;}

Query with Realm SDKs

Note

Swift SDK does not support Realm Query Language

Examples on This Page

Expressions

Parameterized Queries

Query Formats

Dot Notation

Nil Type

Comparison Operators

Important

Types Must Match

Example

Logical Operators

Example

String Operators

Note

Example

ObjectId and UUID Operators

Arithmetic Operators

Type Operator

Dictionary Operators

Example

Date Operators

Example

Aggregate Operators

Example

Collection Operators

Example

List Comparisons

Example

Full Text Search

Full-Text Search Tokenizer Details

Geospatial Queries

Backlink Queries

Subqueries

Example

Sort, Distinct & Limit

Example

Flexible Sync RQL Limitations

Indexed Queryable Fields Subscription Requirements

Unsupported Query Operators in Flexible Sync

List Queries

Warning

Embedded or Linked Objects

Realm Query Language