使用Schematic库时如何更新SQLite数据库Schema及升级时创建新表？

I’ve worked with Schematic quite a bit, so let’s break down exactly how to handle adding new tables when upgrading your database version—this should solve the issue you’re facing.

Step 1: Update Your Database Annotation with the New Table and Version #

First, you need to increment your database version and add the new table class to the tables array in your @Database annotated class. This tells Schematic about the new table structure.

For example, if your original database looked like this:

@Database(version = 1, tables = {OldTable.class})
public abstract class AppDatabase extends SQLiteOpenHelper {
    // ... existing code
}

Update it to:

@Database(version = 2, tables = {OldTable.class, NewTable.class})
public abstract class AppDatabase extends SQLiteOpenHelper {
    // ... existing code
}

Step 2: Define Your New Table with @Table and @Column Annotations #

Create the new table class just like your existing ones, using Schematic’s annotations to define the table name and columns:

@Table(name = "new_table_name")
public class NewTable {
    @Column(name = "_id", type = ColumnType.INTEGER, primaryKey = true, autoIncrement = true)
    public static final String _ID = "_id";

    @Column(name = "column_name", type = ColumnType.TEXT)
    public static final String COLUMN_NAME = "column_name";

    // Add other columns as needed
}

Step 3: Handle the Upgrade in onUpgrade #

Override the onUpgrade method in your AppDatabase class to create the new table when the version increases. Schematic’s TableUtils class has a handy createTable method that generates the correct SQL from your annotated table class:

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // Run migrations based on version differences
    if (oldVersion < 2) {
        // Create the new table when upgrading from v1 to v2
        TableUtils.createTable(db, NewTable.class);
    }
}

Step 4: Update Your Content Provider (If Needed) #

If your new table needs to be accessible via the Content Provider, add its URI to the UriMatcher in your provider class:

public class AppContentProvider extends SchematicProvider {
    @Override
    protected List<UriMatcher> getUriMatchers() {
        return Arrays.asList(
            UriMatcher.of(OldTable.CONTENT_URI, 1),
            UriMatcher.of(NewTable.CONTENT_URI, 2)
        );
    }

    @Override
    protected Database getDatabase() {
        return AppDatabase.getInstance(getContext());
    }
}

Key Notes #

• If you need to modify existing tables (not just add new ones), you’ll need to write manual SQL migration statements in onUpgrade—Schematic doesn’t auto-generate alter table commands, so you’ll have to handle that yourself.
• Make sure you only run each migration once by checking the oldVersion against the new version (this way, users jumping from v1 to v3 will run all necessary migrations).

内容的提问来源于stack exchange，提问作者Kanchan