Explained the need to support database downgrading

collect_app/src/main/java/org/odk/collect/android/database/entities/DatabaseEntitiesRepository.kt

@@ -425,8 +425,4 @@ private class EntitiesDatabaseMigrator :
     }
 
     override fun onUpgrade(db: SQLiteDatabase?, oldVersion: Int) = Unit
-
-    override fun onDowngrade(db: SQLiteDatabase?) {
-        TODO("Not yet implemented")
-    }
 }

collect_app/src/main/java/org/odk/collect/android/database/forms/FormDatabaseMigrator.java

@@ -80,11 +80,6 @@ public void onUpgrade(SQLiteDatabase db, int oldVersion) throws SQLException {
         }
     }
 
-    public void onDowngrade(SQLiteDatabase db) throws SQLException {
-        SQLiteUtils.dropTable(db, FORMS_TABLE_NAME);
-        createFormsTableV13(db);
-    }
-
     private void upgradeToVersion2(SQLiteDatabase db) {
         SQLiteUtils.dropTable(db, FORMS_TABLE_NAME);
         onCreate(db);

collect_app/src/main/java/org/odk/collect/android/database/instances/InstanceDatabaseMigrator.java

@@ -66,11 +66,6 @@ public void onUpgrade(SQLiteDatabase db, int oldVersion) {
         }
     }
 
-    public void onDowngrade(SQLiteDatabase db) {
-        SQLiteUtils.dropTable(db, INSTANCES_TABLE_NAME);
-        createInstancesTableV8(db);
-    }
-
     private void upgradeToVersion2(SQLiteDatabase db) {
         if (!doesColumnExist(db, INSTANCES_TABLE_NAME, CAN_EDIT_WHEN_COMPLETE)) {
             SQLiteUtils.addColumn(db, INSTANCES_TABLE_NAME, CAN_EDIT_WHEN_COMPLETE, "text");

collect_app/src/main/java/org/odk/collect/android/database/savepoints/SavepointsDatabaseMigrator.kt

@@ -8,7 +8,6 @@ import org.odk.collect.android.database.savepoints.DatabaseSavepointsColumns.INS
 import org.odk.collect.android.database.savepoints.DatabaseSavepointsColumns.INSTANCE_FILE_PATH
 import org.odk.collect.android.database.savepoints.DatabaseSavepointsColumns.SAVEPOINT_FILE_PATH
 import org.odk.collect.db.sqlite.DatabaseMigrator
-import org.odk.collect.db.sqlite.SQLiteUtils
 
 class SavepointsDatabaseMigrator :
     DatabaseMigrator {
@@ -25,11 +24,6 @@ class SavepointsDatabaseMigrator :
         }
     }
 
-    override fun onDowngrade(db: SQLiteDatabase) {
-        SQLiteUtils.dropTable(db, SAVEPOINTS_TABLE_NAME)
-        createSavepointsTableV1(db)
-    }
-
     private fun createSavepointsTableV1(db: SQLiteDatabase) {
         db.execSQL(
             "CREATE TABLE IF NOT EXISTS $SAVEPOINTS_TABLE_NAME (" +

collect_app/src/test/java/org/odk/collect/android/database/FormDatabaseMigratorTest.java

@@ -11,7 +11,6 @@
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.odk.collect.android.database.forms.FormDatabaseMigrator;
-import org.odk.collect.db.sqlite.SQLiteUtils;
 
 import java.util.List;
 
@@ -309,59 +308,6 @@ public void onUpgrade_fromVersion7() {
         }
     }
 
-    @Test
-    public void onDowngrade_fromVersionWithExtraColumn() {
-        FormDatabaseMigrator formDatabaseMigrator = new FormDatabaseMigrator();
-        formDatabaseMigrator.onCreate(database);
-        SQLiteUtils.addColumn(database, FORMS_TABLE_NAME, "new_column", "text");
-        ContentValues contentValues = createVersion8Form();
-        contentValues.put("new_column", "blah");
-        database.insert(FORMS_TABLE_NAME, null, contentValues);
-
-        formDatabaseMigrator.onDowngrade(database);
-
-        try (Cursor cursor = database.rawQuery("SELECT * FROM " + FORMS_TABLE_NAME + ";", new String[]{})) {
-            assertThat(cursor.getColumnCount(), is(18));
-            assertThat(cursor.getCount(), is(0));
-            assertThat(asList(cursor.getColumnNames()), is(CURRENT_VERSION_COLUMNS));
-        }
-    }
-
-    @Test
-    public void onDowngrade_fromVersionWithMissingColumn() {
-        // Create form table with out JR Cache column
-        FormDatabaseMigrator formDatabaseMigrator = new FormDatabaseMigrator();
-        database.execSQL("CREATE TABLE IF NOT EXISTS " + FORMS_TABLE_NAME + " ("
-                + _ID + " integer primary key, "
-                + DISPLAY_NAME + " text not null, "
-                + DESCRIPTION + " text, "
-                + JR_FORM_ID + " text not null, "
-                + JR_VERSION + " text, "
-                + MD5_HASH + " text not null, "
-                + DATE + " integer not null, "
-                + FORM_MEDIA_PATH + " text not null, "
-                + FORM_FILE_PATH + " text not null, "
-                + LANGUAGE + " text, "
-                + SUBMISSION_URI + " text, "
-                + BASE64_RSA_PUBLIC_KEY + " text, "
-                + AUTO_SEND + " text, "
-                + AUTO_DELETE + " text, "
-                + LAST_DETECTED_FORM_VERSION_HASH + " text, "
-                + GEOMETRY_XPATH + " text);");
-
-        ContentValues contentValues = createVersion8Form();
-        contentValues.remove(JRCACHE_FILE_PATH);
-        database.insert(FORMS_TABLE_NAME, null, contentValues);
-
-        formDatabaseMigrator.onDowngrade(database);
-
-        try (Cursor cursor = database.rawQuery("SELECT * FROM " + FORMS_TABLE_NAME + ";", new String[]{})) {
-            assertThat(cursor.getColumnCount(), is(18));
-            assertThat(cursor.getCount(), is(0));
-            assertThat(asList(cursor.getColumnNames()), is(CURRENT_VERSION_COLUMNS));
-        }
-    }
-
     private ContentValues createVersion8Form() {
         ContentValues contentValues = new ContentValues();
         contentValues.put(DISPLAY_NAME, "DisplayName");

db/src/main/java/org/odk/collect/db/sqlite/DatabaseConnection.kt

@@ -97,7 +97,7 @@ open class DatabaseConnection @JvmOverloads constructor(
 }
 
 /**
- * [SQLiteOpenHelper] that delegates `onCreate`, `onUpdate`, `onDowngrade` to a [DatabaseMigrator].
+ * [SQLiteOpenHelper] that delegates `onCreate`, `onUpdate` to a [DatabaseMigrator].
  */
 private class DatabaseMigratorSQLiteOpenHelper(
     context: Context,
@@ -120,14 +120,4 @@ private class DatabaseMigratorSQLiteOpenHelper(
             newVersion
         )
     }
-
-    override fun onDowngrade(db: SQLiteDatabase?, oldVersion: Int, newVersion: Int) {
-        Timber.i("Downgrading database from version %d to %d", oldVersion, newVersion)
-        databaseMigrator.onDowngrade(db)
-        Timber.i(
-            "Downgrading database from %d to %d completed with success.",
-            oldVersion,
-            newVersion
-        )
-    }
 }

db/src/main/java/org/odk/collect/db/sqlite/DatabaseMigrator.java

@@ -6,6 +6,4 @@ public interface DatabaseMigrator {
     void onCreate(SQLiteDatabase db);
 
     void onUpgrade(SQLiteDatabase db, int oldVersion);
-
-    void onDowngrade(SQLiteDatabase db);
 }