By default a Realm can store all classes extending RealmObject in a project. However, if you want to restrict a Realm to only contain a subset of classes or want to share them between a library project and an app project, you must use a RealmModule.A RealmModule is a collection of classes extending RealmObject that can be combined with other RealmModules to create the schema for a Realm. This makes it easier to control versioning and migration of those Realms.
A RealmModule can either be a library module or an app module. The distinction is made by setting
library = true . Setting
library = true is normally only relevant for library authors. See below for further details.
Currently, it is not possible to have multiple RealmModule declarations in a single file. If you have more than one RealmModule, you will have to use separate Java files for each module.
Realms default behavior is to automatically create a RealmModule called
DefaultRealmModule which contains all classes extending RealmObject in a project. This module is automatically known by Realm.
This behavior is problematic when combining a library project and an app project that both uses Realm. This is because the
DefaultRealmModule will be created for both the library project and the app project, which will cause the project to fail with duplicate class definition errors.
Library authors are responsible for avoiding this conflict by using explicit modules where
library = true is set. This disables the generation of the DefaultRealmModule for the library project and allows the library to be included in the app project that also uses Realm. This means that library projects that uses Realm internally are required to specify a specific module using
App developers are not required to specify any modules, as they implicitly use the
DefaultRealmModule , but they now has the option of adding the library project classes to their schema using
Modifier and Type
Optional Element and Description
Instead of adding all Realm classes manually to a module, set this boolean to true to automatically include all Realm classes in this project.
The naming policy applied to all classes part of this module.
Specifies the classes extending RealmObject that should be part of this module.
The naming policy applied to all field names in all classes part of this module.
Setting this to true will mark this module as a library module.
Instead of adding all Realm classes manually to a module, set this boolean to true to automatically include all Realm classes in this project. This does not include classes from other libraries which must be exposed using their own module. Setting both
It is possible to override the naming policy specified in the module in each class using the RealmClass annotation.
If a class is part of multiple modules, the same naming policy must be applied to both modules, otherwise an error will be thrown.
Specifies the classes extending RealmObject that should be part of this module. Only classes in this project can be included. Classes from other libraries must be exposed using their own module. Setting both
The naming policy applied to all field names in all classes part of this module. The default policy is RealmNamingPolicy.NO_POLICY . To define a naming policy for class names, use classNamingPolicy() .
Setting this to true will mark this module as a library module. This will prevent Realm from generating the