Room model generator

Generate Room entities from plain java/kotlin models located in java-library module.

Problem

If you tend to use plain java/kotlin module for you'r logic, you might have created interface for database to be implemented and provided from android code and while doing that you were probably thinking how to solve entities issue, you have model defined in non android module and you need android annotations to use it in database. This would require writing the same model in android module with proper annotations, ewentually you could create model with PrimaryKey and add all model logic with Embedded annotation, in kotlin this would shorten to

data class KotlinModel(val id: String, val name:String)

@RoomEntity
data class RoomEntity(val kotlinModel: KotlinModel, @PrimaryKey val id: String = kotlinModel.id)

But still if you would like to rename or ignore some fields from you'r model you would have to probably write the same model again, also add some extensions to transform model into entity and entity back into model.

What if this all could be done for you? If you could annotate your non-android model with room-similar annotations and receive proper entity? With all the extension methods written?

Usage

Create your non-android models like you did before, but annotate them with RoomEntity, optionally you can annotate all fields, or add other room alike annotations - for more info check another chapter Supported annotations. When you have your models ready simply create data class containing all the classes annotated with RoomEntities

@RoomEntity
data class Cow(val id: String)

@RoomEntities
data class Entities(val cow:Cow)

Eventually if you are using java:

@RoomEntities
public class JavaEntities {
    private Cow cow;
}

Processor will generate automatically CowRoom class with Room annotations and proper extension methods are going to be created

fun Cow.entity() = CowRoom(id)

fun List<Cow>.entities() = map { it.entity() }

fun List<CowRoom>.models() = map { it.model() }

Also generated class contains method 'model()' which allows you to transform single entity straight to model:

val cow: Cow = Cow("id").entity().model()

Supported annotations

Entity -> RoomEntity

All non-android models have to be annotated with @RoomEntity before beign added to @RoomEntities class. Optionally you can define tableName if you would like your database table name to be different

@RoomEntity("users")
data class User(val id: String)

PrimaryKey -> RoomPrimaryKey

In an entity one field has to be either annotated with @RoomPrimaryKey or eventually called id. If there will be field annotated with @RoomPrimaryKey and other field called id that id will not be taken into entity generation. It only will be if there are no present annotations. Optionally you can mark primary key as auto generated

data class User(@PrimaryKey(true) val primary: String)

data class User(val id: String)

ColumnInfo -> RoomName

Field in model class can also be annotated with @RoomName if you would like to change its name.

data class User(@RoomName("user_name") val name: String)

Ignore -> RoomIgnore

If you would like to skip some fields from adding to database you can annotate them with @RoomIgnore

data class User(@RoomIgnore val avatarFile: File)

Embedded -> RoomEmbedded

Works just the same as rooms embedded annotation, ie signals that nested fields (i.e. fields of the annotated field's class) can be referenced directly in the SQL queries Keep in mind that currently it does not transform @RoomNames and other annotations from inner class to room annotations.

data class Inner(val name: String)

data class Outer(@RoomEmbedded val inner: Inner)

ForeignKeys -> RoomForeignKeys

If you would like to add some relations you can mark your model with @RoomForeignKey just like you would with standard room ForeignKey

@RoomEntity
@ForeignKey([ForeignKey]
data class User(val id: String)

ForeignKey -> RoomForeignKey

Strictly connected with ForeignKeys. There is one small change to default room implementation, you do not specify class directly but instead its name (this will be addressed in future releases). So you have to specify: entityClassName, array of parent columns and array of child columns.

@RoomEntity
@RoomForeignKeys([(RoomForeignKey("Cow", ["id"], ["cowId"]))])
data class User(val id: String, val cowId: String)

To be done

Actually indexes are not supported. They will be supported in upcoming release.

Download

Add as gradle dependency straight from jCenter: In your non-android module all you need is:

compileOnly "com.zagorski:room-model-generator-annotations:$roomGeneratorVersion"

And in your android, assuming you are using kotlin:

compileOnly "com.zagorski:room-model-generator-annotations:$roomGeneratorVersion"
kapt "com.zagorski:room-model-generator-processor:$roomGeneratorVersion"

For current version check badge at the top or github releases tab.

License

Copyright 2018 Mateusz Zagórski.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.