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Room - Schema export directory is not provided to the annotation processor so we cannot export the schema

java
room
annotation-processing
kotlin
Anton ShumikhinbyAnton Shumikhin·Mar 5, 2025
TLDR

Fix the Room schema export issue by adding the schema directory in your build.gradle:

android { defaultConfig { javaCompileOptions { annotationProcessorOptions { // Trust me, it's not too complicated... It only seems so! arguments = ["room.schemaLocation": "$projectDir/schemas"] } } } }

Make sure the integer schemas folder exists in your projectDir. And voila... Room handles the rest, generating schema files there!

Optimizing version control, team co-op, and Kotlin nuances

Precise version tracking for smoother migrations

Precise tracking of your database schemas over time allows you to handle those tricky migration scenarios efficiently.

// Control your database schema like a boss exportSchema = true

Safeguard database changes with rollbacks

Having all your schemas under version control provides a haven for damage control; things go south, roll it back!

// Garbage, huh? Rollback time! git checkout HEAD~1

Effective team collaboration with shared schema access

Consistency is king in a team project. With schema files checked into source control, your team stays on the same page with the database structure.

// Hey Bob, pull the latest changes... and no more coffee stains on the schemas, please! git pull

Kotlin lovers, meet kotlin-kapt

For Kotlin projects, you'd need to utilize the kotlin-kapt plugin for correct annotation processing. Here's the rune:

kapt { arguments { // Kotlin and Room walk into a bar and... guess what they order? arg("room.schemaLocation", "$projectDir/schemas") } }

Deep dive into Room configuration

Choosing your personalized path to wisdom

Your project structure is a unique snowflake. Specify a different path for schema files if needed:

// Because who needs uniformity? arguments = ["room.schemaLocation": "$projectDir/customschemas"]

Silence the sirens with exportSchema declaration

For small projects or quick prototypes where database history is trivial, silence the warning sirens by setting exportSchema to false.

// Silent running... engage! @Database(entities = {MyEntity.class}, version = 1, exportSchema = false)

Keep your foundation solid

Your historical schema evolution forms the foundation of your app. Keep it solid by updating your schema files regularly with each change in the database.

// Keeping up with the Joneses, Room style! git commit -m "Update schema to reflect recent db changes"

Room-Kotlin harmony: The annotation processing equation

Juggling Room and Kotlin? It's straightforward to ensure compatibility, just maintain accuracy in your annotationProcessorOptions for smooth-sailing database management.