Lenguaje de consulta de reino

Query with Realm SDKs

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

Expresiones

Los filtros consisten en expresiones dentro de un predicado. Una expresión consta de uno de los siguientes:

• The name of a property of the object currently being evaluated.

• Un operador y hasta dos expresiones de argumento. Por ejemplo, en la expresión A + B, A + B es una expresión, pero A y B también son expresiones de argumento para el operador +.

• 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"

Incluye múltiples parámetros con números enteros ascendentes a partir de $0.

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

Notación de puntos

Al referirse a la propiedad de un objeto, se puede utilizar la notación de puntos para referirse a las propiedades secundarias de ese objeto. Incluso se puede hacer referencia a las propiedades de objetos incrustados y relaciones con la notación de puntos.

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

Operadores de comparación

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

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

  // 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

Operadores lógicos

Make compound predicates using logical operators.

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

Operadores de String

Compara valores de strings utilizando estos operadores de strings. Los comodines tipo Regex permiten una mayor flexibilidad en la búsqueda.

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

ObjectId and UUID Operators

Consulta los ObjectIds y UUID de BSON. Estos tipos de datos se utilizan a menudo como claves principales.

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)"

Para realizar consultas con UUID, coloque una representación de cadena del UUID que está evaluando en uuid(<UUID String>).

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

Operadores aritméticos

Realizar operaciones aritméticas básicas en un lado de una expresión RQL al evaluar tipos de datos numéricos.

  "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"

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.

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

Dictionary Operators

Compare dictionary values using these dictionary operators.

También puede usar operadores de diccionario junto con operadores de comparación para filtrar objetos según sus claves y valores. Los siguientes ejemplos muestran cómo usar operadores de diccionario con operadores de comparación. Todos los ejemplos consultan una colección de objetos Realm con una propiedad de diccionario dict llamada.

  // 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'"

Operadores de fecha

query tipos de fecha en un 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.

• Como un tiempo en segundos desde la Unix epoch- Ts:n, donde T designa el inicio del tiempo, s es el número de segundos y n es el número de nanosegundos.

Date supports comparison operators.

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.

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.

  // 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"

Comparaciones de listas

Puede utilizar operadores de comparación y operadores de colección para filtrar según listas de datos.

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

• colecciones de objetos Realm, que le permiten filtrar con respecto a otros datos en el reino.

  "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}"

• objetos de lista nativos pasados ​​en una expresión parametrizada, que le permiten pasar datos de la aplicación directamente a sus consultas.

  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.

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

Full Text Search

Puede utilizar RQL para consultar propiedades que tengan una anotación de búsqueda de texto completo (FTS). FTS admite búsquedas de coincidencia booleana de palabras, en lugar de búsquedas por relevancia. Para obtener información sobre cómo habilitar el FTS en una propiedad, consulte la documentación de FTS correspondiente a su SDK:

• Flutter SDK

• Kotlin SDK

• Kit de desarrollo de software .NET

• Node.js SDK

• React Native SDK

• El SDK de Swift aún no admite la Búsqueda de Texto Completo.

Para consultar estas propiedades, utiliza el predicado TEXT en tu 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.

En el siguiente ejemplo, consultamos la propiedad Item.name:

    // 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*"

Query geoespacial

Puedes realizar query sobre datos geoespaciales utilizando el operador geoWithin. El operador geoWithin toma el par de latitud/longitud en la propiedad coordinates de un objeto personalizado incrustado y una forma geoespacial. El operador verifica si el punto cordinates está contenido dentro de la forma geoespacial.

The following geospatial shapes are supported for querying:

• GeoCircle

• GeoBox

• GeoPolygon

Para query datos geoespaciales:

1. Crea un objeto con una propiedad que contenga los datos geoespaciales incorporados.

2. Define la forma geoespacial para establecer el límite de la query.

3. 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

Para obtener más información sobre cómo definir formas y objetos geoespaciales con datos geoespaciales integrados, consulte la documentación geoespacial de su SDK:

• Flutter SDK

• Kotlin SDK

• Kit de desarrollo de software .NET

• Node.js SDK

• React Native SDK

• Kit de desarrollo de software de Swift

Queries de vínculos inversos

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"

El resultado de un vínculo inverso se trata como una colección y soporta operadores de colección.

  // 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"

Puede utilizar operadores agregados en la colección de vínculos de retroceso.

  // 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"

Puede consultar la cantidad de todas las relaciones que apuntan a un objeto utilizando el operador @count directamente en @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

• Contando el número de objetos que coinciden con una subconsulta

SUBQUERY() has the following structure:

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

• collection: The name of the property to iterate through

• variableName:Un nombre de variable del elemento a utilizar en la subconsulta

• predicate: El predicado de subconsulta. Utiliza la variable especificada por variableName para referirse al elemento que se está iterando actualmente.

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.

Puedes usar el conteo del resultado de la subconsulta como cualquier otro número en una expresión válida. En particular, puedes comparar el conteo con el número 0 para devolver todos los objetos coincidentes.

  // 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.

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

Flexible Sync RQL Limitations

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

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

// 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"