Room Column Field Generator (Work In Progress)

Inspired from RealmFieldNamesHelper

Update

This library doesn't work with clean build, sadly. Will try to fix and make it work when I have time. May be you can help me out? https://stackoverflow.com/questions/55995947/how-to-make-my-custom-annotation-processor-for-room-entities-run-before-room-ann

What does it do?

This is an annotation processor which detects all Room Entites and generates a Kotlin class for each Entity with fields representing Column names. For example, for the following Entity,

@Entity
class Test {
    var field1: String = ""
    var fieldTwo: Int = -1
}

following Kotlin class is generated.

object TestFields {
    const val FIELD1: String = "field1"

    const val FIELD_TWO: String = "fieldTwo"
}

As you can see, the generated Kotlin class name would be <EntityName>Fields . If tableName is specified inside Entity annotation, that will be used. Else, Entitiy class name will be used.

Why?

In Room, Columns of the Entities can be annotated with ColumnInfo annotation to provide extra details and change column name. It is a best practice to provide column name through ColumnInfo annotation even though that name and the field name is same.

The reason is, Room uses the annotation value if available, else gets the column name from the field name through reflection. This might be a problem if proguard/r8 is enabled since Entity fields might be obfuscated and that obfuscated name will be used as column name. This can be avoided by adding keep rules for all Entities or adding column name explicitly through @ColumnInfo annoation.

If both names are same, it would be a boilerplace to put raw string in all column names. With this library, you can do this

@ColumnInfo(name = TestFields.FIELD1)
var field1: String = ""

instead of this

@ColumnInfo(name = "field1")
var field1: String = ""

Some other interesting use cases are, you can use the generted const fields in

• @ForeignKey parentColumns and childColumns
• @ColumnInfo name for POJO classes to return subset of columns

Installation

Step 1: Add this in your root build.gradle at the end of repositories:

allprojects {
   	repositories {
   		...
   		maven { url 'https://jitpack.io' }
   	}
   }

Step 2: Add the dependency

dependencies {
         ...
           kapt 'com.github.muthuraj57:roomColumnFieldGenerator:0.2'
   }

Step 3: Sync and Run/Rebuild the project. Kolin helper classes would have been generated for all Entities now.

Note:

This library creates Kotlin files, so Kotlin should be enabled in your project.