see on GitHub

Session: Querying: How to Query

This session explains the following methods to query a database:

  • session.query()
  • session.advanced.documentQuery()
  • session.advanced.rawQuery()

Session.Query

The most straightforward way to issue a query is by using the query() method.

Syntax

session.query(documentType);
session.query(options);

Parameters
documentType class A class constructor used for reviving the results' entities from which the collection name is determined
options object
  indexName string Name of an index to perform a query on (exclusive with collectionName)
  collection string Name of a collection to perform a query on (exclusive with indexName)
  documentType function A class constructor used for reviving the results' entities
Return Value
Promise<IDocumentQuery> Promise resolving to instance implementing IDocumentQuery interface containing additional query methods

Example I - Basic Dynamic Query

// load all entities from 'Employees' collection
const employees = await session.query(Employee)
    .all();

// or without passing type
const employees2 = await session.query({ collection: "Employees" })
    .all();

The above is an example of a dynamic query which doesn't require you to specify an index name. RavenDB will create an auto index automatically if necessary.

The provided Employee type as the generic type parameter does not only define the type of returned results, but it also indicates that the queried collection will be Employees.

Example II - Query Syntax

// load all entities from 'Employees' collection
// where FirstName equals 'Robert'
const employees = await session.query({ collection: "Employees" })
    .whereEquals("FirstName", "Robert")
    .all();

Example III - Using Specific Index

// load all entities from 'Employees' collection
// where firstName equals 'Robert'
// using 'Employees/ByName' index
const employees = await session.query({ indexName: "Employees/ByName" })
    .whereEquals("FirstName", "Robert")
    .all();

session.advanced.documentQuery()

Example IV

// load all employees hired between
// 1/1/2002 and 12/31/2002
const employees = await session.advanced.documentQuery(Employee)
    .whereBetween("HiredAt",
        new Date("2002-01-01"), new Date("2002-12-31"))
    .all();

session.advanced.rawQuery()

Queries in RavenDB use a SQL-like language called RavenDB Query Language (RQL). All of the above queries generate RQL sent to the server. The session also gives you the way to express the query directly in RQL using rawQuery() method.

Example IV

// load all entities from 'Employees' collection
// where FirstName equals 'Robert
const employees = await session.advanced
    .rawQuery("from Employees where FirstName = 'Robert'")
    .all();

On entities loading, JS classes and the documentType parameter

Type information about the entity and its contents is by default stored in the document metadata. Based on that its types are revived when loaded from the server.

Entity type registration

In order to avoid passing documentType argument every time, you can register the type in the document conventions using the registerEntityType() method before calling DocumentStore's initialize() like so:

class Pet {
    constructor(name) {
        this.name = name;
    }
}

class Person {
    constructor(name, pet) {
        this.name = name;
        this.pet = pet;
    }
}

documentStore.conventions.registerEntityType(Person);
documentStore.conventions.registerEntityType(Pet);
// ...

documentStore.initialize();

If you fail to do so, entities (and all subobjects) loaded from the server are going to be plain object literals and not instances of the original type they were stored with.