Roomie

Roomie is an annotation processing library that utilizes KSP to generate TypeConverter classes for Room. TypeConverter classes most often involve same boiler-plate code and Roomie makes it really easy to quickly create them with a single annotation.

Usage

Annotate the specific model class using @AddConverter

@AddConverter
data class Person(val firstName: String, val lastName: String)

It's as simple as that! Rebuild the project to generate the converter. A converter class with the name PersonConverter will be generated for the Person data class above. In your case, use [Model name]Converter to get the corresponding converter for your data class.

Specifying converter name

By default, the generated converter has Converter appended to its name but it can be changed by using the name argument specified in @AddConverter annotation.

@AddConverter(name = "PeopleConverter")
data class Person(val firstName: String, val lastName: String)

This will generate the converter using PeopleConverter as its name.

Working with lists

By default, the generated converter class will be similar to the code below:

open class PersonConverter {
  @TypeConverter
  fun fromString(value: String): Person {
    val type = object : TypeToken<Person>() {}.type
    return Gson().fromJson<Person>(value, type)
  }

  @TypeConverter
  fun fromList(value: Person): String {
    val gson = Gson()
    return gson.toJson(value)
  }
}

In certain cases you may want to wrap the model class with a kotlin list. This can be achieved by using the asList argument which takes a boolean specified in @AddConverter annotation, which by default is false.

@AddConverter(asList = true)
data class Person(val firstName: String, val lastName: String)

The resulting generated converter class is shown below:

open class PersonListConverter {
  @TypeConverter
  fun fromString(value: String): List<Person> {
    val type = object : TypeToken<List<Person>>() {}.type
    return Gson().fromJson<List<Person>>(value, type)
  }

  @TypeConverter
  fun fromList(value: List<Person>): String {
    val gson = Gson()
    return gson.toJson(value)
  }
}

• In this case the resulting converter class now has ListConverter appended to its name. To get the corresponding converter class when asList is set to true append ListConverter to its name, as in [Model name]ListConverter.

Download

1. Add the JitPack repository to your project

groovy - settings.gradle (project level)

repositories {
    google()
    mavenCentral()
    jcenter() // Warning: this repository is going to shut down soon
    maven { url 'https://jitpack.io' }
  }

kotlin - setting.gradle.kts

dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        google()
        mavenCentral()
        maven { url = uri("https://www.jitpack.io" ) }
    }
}

2. Add the KSP plugin:

The version you chose for the KSP plugin depends on the Kotlin version your project uses.
You can check https://github.com/google/ksp/releases for the list of KSP versions, then pick the last release that matches your Kotlin version.
Example: If you're using 1.5.30 Kotlin version, then the corresponding KSP version is 1.5.30-1.0.0.

groovy - build.gradle (module level)

plugins {
    //...
    id 'com.google.devtools.ksp' version '1.5.30-1.0.0' // Depends on your kotlin version
}

kotlin - build.gradle.kts (module level)

plugins {
    //...
    id("com.google.devtools.ksp") version "1.5.30-1.0.0" // Depends on your kotlin version
}

3. Add depedencies:

groovy - build.gradle (module level)

implementation 'com.github.ezechuka.roomie:roomie-annotation:1.0.0-beta02'
ksp 'com.github.ezechuka.roomie:roomie-processor:1.0.0-beta02'

kotlin - build.gradle.kts (module level)

implementation("com.github.ezechuka.roomie:roomie-annotation:1.0.0-beta02")
ksp("com.github.ezechuka.roomie:roomie-processor:1.0.0-beta02")

Also Room and Gson needs to be included in the build.gradle (module level) for Groovy or build.gradle.kts (module level) for Kotlin

4. Specify build generated folder to IDE

Within the android block add:

groovy - build.gradle (module level)

applicationVariants.all { variant ->
    kotlin.sourceSets {
        getByName(variant.name) {
            kotlin.srcDir("build/generated/ksp/${variant.name}/kotlin")
        }
    }
}

kotlin - build.gradle.kts (module level)

applicationVariants.all {
    kotlin.sourceSets {
        getByName(name) {
            kotlin.srcDir("build/generated/ksp/$name/kotlin")
        }
    }
}