# MigrationKt

Added in 2.7.0

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```
public final class MigrationKt
```

<br />

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## Summary

| ### Public methods |
|---|---|
| `static final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/room/migration/Migration` | `https://developer.android.com/reference/androidx/room/migration/MigrationKt#Migration(kotlin.Int,kotlin.Int,kotlin.Function1)( int startVersion, int endVersion, @https://developer.android.com/reference/androidx/annotation/NonNull Function1<@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/sqlite/db/SupportSQLiteDatabase, https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html> migrate )` Creates `https://developer.android.com/reference/androidx/room/migration/package-summary#Migration(kotlin.Int,kotlin.Int,kotlin.Function1)` from `https://developer.android.com/reference/androidx/room/migration/package-summary#Migration(kotlin.Int,kotlin.Int,kotlin.Function1)` to `https://developer.android.com/reference/androidx/room/migration/package-summary#Migration(kotlin.Int,kotlin.Int,kotlin.Function1)` that runs `https://developer.android.com/reference/androidx/room/migration/package-summary#Migration(kotlin.Int,kotlin.Int,kotlin.Function1)` to perform the necessary migrations. |

## Public methods

### Migration

Artifact: [androidx.room:room-runtime](https://developer.android.com/jetpack/androidx/releases/room) [View Source](https://cs.android.com/search?q=file:androidx/room/migration/Migration.android.kt+function:Migration) Added in [2.7.0](https://developer.android.com/jetpack/androidx/releases/room#2.7.0)

```
public static final @NonNull Migration Migration(
    int startVersion,
    int endVersion,
    @NonNull Function1<@NonNull SupportSQLiteDatabase, Unit> migrate
)
```

Creates `https://developer.android.com/reference/androidx/room/migration/package-summary#Migration(kotlin.Int,kotlin.Int,kotlin.Function1)` from `https://developer.android.com/reference/androidx/room/migration/package-summary#Migration(kotlin.Int,kotlin.Int,kotlin.Function1)` to `https://developer.android.com/reference/androidx/room/migration/package-summary#Migration(kotlin.Int,kotlin.Int,kotlin.Function1)` that runs `https://developer.android.com/reference/androidx/room/migration/package-summary#Migration(kotlin.Int,kotlin.Int,kotlin.Function1)` to perform the necessary migrations.

A migration can handle more than 1 version (e.g. if you have a faster path to choose when going version 3 to 5 without going to version 4). If Room opens a database at version 3 and latest version is \< 5, Room will use the migration object that can migrate from 3 to 5 instead of 3 to 4 and 4 to 5.

If there are not enough migrations provided to move from the current version to the latest version, Room will clear the database and recreate so even if you have no changes between 2 versions, you should still provide a Migration object to the builder.

`https://developer.android.com/reference/androidx/room/migration/package-summary#Migration(kotlin.Int,kotlin.Int,kotlin.Function1)` cannot access any generated Dao in this method.

`https://developer.android.com/reference/androidx/room/migration/package-summary#Migration(kotlin.Int,kotlin.Int,kotlin.Function1)` is already called inside a transaction and that transaction might actually be a composite transaction of all necessary `Migration`s.