android-GreenDAO架构更新和数据迁移?

我正在评估GreenDAO,以便在我将要研究的商业Android应用程序中进行考虑,并希望确定架构更新的迁移路径。

我断言必须写一个自定义的OpenHelper来提供新的onUpdate()并根据新模式提取转换并存储数据,这对吗? 这种假设引起了一些有关呼叫顺序和责任划分的有趣问题。

我找不到有关GreenDAO的架构更新和数据迁移的任何文档。

这是我写过的许多关于此主题的博客文章:

  1. greenDAO的评论
  2. 第1部分–模式生成
  3. 第2部分–模式迁移
  4. 第3部分–测试架构迁移
Syntax asked 2019-11-08T09:08:15Z
7个解决方案
38 votes

考虑到pleonasmik的方法(顺便说一句,谢谢,它确实很有帮助),我创建了一个MigrationHelper类。

这个怎么运作:

  1. 班上所有你得到的道教
  2. 根据旧版本的方案创建临时表(restoreData方法)
  3. 将所有数据导入到此新表中(restoreData方法)
  4. 删除旧版本的所有表(restoreData方法)
  5. 创建新版本的表(restoreData方法)
  6. 从临时更新新版本的表(restoreData方法)
  7. 删除所有临时表(restoreData方法)

迁移助手类:

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.text.TextUtils;
import android.util.Log;

import com.crashlytics.android.Crashlytics;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import de.greenrobot.dao.AbstractDao;
import de.greenrobot.dao.internal.DaoConfig;
import greendao.DaoMaster;


/**
 * Created by pokawa on 18/05/15.
 */
public class MigrationHelper {

    private static final String CONVERSION_CLASS_NOT_FOUND_EXCEPTION = "MIGRATION HELPER - CLASS DOESN'T MATCH WITH THE CURRENT PARAMETERS";
    private static MigrationHelper instance;

    public static MigrationHelper getInstance() {
        if(instance == null) {
            instance = new MigrationHelper();
        }
        return instance;
    }

    public void migrate(SQLiteDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        generateTempTables(db, daoClasses);
        DaoMaster.dropAllTables(db, true);
        DaoMaster.createAllTables(db, false);
        restoreData(db, daoClasses);
    }

    private void generateTempTables(SQLiteDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        for(int i = 0; i < daoClasses.length; i++) {
            DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);

            String divider = "";
            String tableName = daoConfig.tablename;
            String tempTableName = daoConfig.tablename.concat("_TEMP");
            ArrayList<String> properties = new ArrayList<>();

            StringBuilder createTableStringBuilder = new StringBuilder();

            createTableStringBuilder.append("CREATE TABLE ").append(tempTableName).append(" (");

            for(int j = 0; j < daoConfig.properties.length; j++) {
                String columnName = daoConfig.properties[j].columnName;

                if(getColumns(db, tableName).contains(columnName)) {
                    properties.add(columnName);

                    String type = null;

                    try {
                        type = getTypeByClass(daoConfig.properties[j].type);
                    } catch (Exception exception) {
                        Crashlytics.logException(exception);
                    }

                    createTableStringBuilder.append(divider).append(columnName).append(" ").append(type);

                    if(daoConfig.properties[j].primaryKey) {
                        createTableStringBuilder.append(" PRIMARY KEY");
                    }

                    divider = ",";
                }
            }
            createTableStringBuilder.append(");");

            db.execSQL(createTableStringBuilder.toString());

            StringBuilder insertTableStringBuilder = new StringBuilder();

            insertTableStringBuilder.append("INSERT INTO ").append(tempTableName).append(" (");
            insertTableStringBuilder.append(TextUtils.join(",", properties));
            insertTableStringBuilder.append(") SELECT ");
            insertTableStringBuilder.append(TextUtils.join(",", properties));
            insertTableStringBuilder.append(" FROM ").append(tableName).append(";");

            db.execSQL(insertTableStringBuilder.toString());
        }
    }

    private void restoreData(SQLiteDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        for(int i = 0; i < daoClasses.length; i++) {
            DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);

            String tableName = daoConfig.tablename;
            String tempTableName = daoConfig.tablename.concat("_TEMP");
            ArrayList<String> properties = new ArrayList();

            for (int j = 0; j < daoConfig.properties.length; j++) {
                String columnName = daoConfig.properties[j].columnName;

                if(getColumns(db, tempTableName).contains(columnName)) {
                    properties.add(columnName);
                }
            }

            StringBuilder insertTableStringBuilder = new StringBuilder();

            insertTableStringBuilder.append("INSERT INTO ").append(tableName).append(" (");
            insertTableStringBuilder.append(TextUtils.join(",", properties));
            insertTableStringBuilder.append(") SELECT ");
            insertTableStringBuilder.append(TextUtils.join(",", properties));
            insertTableStringBuilder.append(" FROM ").append(tempTableName).append(";");

            StringBuilder dropTableStringBuilder = new StringBuilder();

            dropTableStringBuilder.append("DROP TABLE ").append(tempTableName);

            db.execSQL(insertTableStringBuilder.toString());
            db.execSQL(dropTableStringBuilder.toString());
        }
    }

    private String getTypeByClass(Class<?> type) throws Exception {
        if(type.equals(String.class)) {
            return "TEXT";
        }
        if(type.equals(Long.class) || type.equals(Integer.class) || type.equals(long.class)) {
            return "INTEGER";
        }
        if(type.equals(Boolean.class)) {
            return "BOOLEAN";
        }

        Exception exception = new Exception(CONVERSION_CLASS_NOT_FOUND_EXCEPTION.concat(" - Class: ").concat(type.toString()));
        Crashlytics.logException(exception);
        throw exception;
    }

    private static List<String> getColumns(SQLiteDatabase db, String tableName) {
        List<String> columns = new ArrayList<>();
        Cursor cursor = null;
        try {
            cursor = db.rawQuery("SELECT * FROM " + tableName + " limit 1", null);
            if (cursor != null) {
                columns = new ArrayList<>(Arrays.asList(cursor.getColumnNames()));
            }
        } catch (Exception e) {
            Log.v(tableName, e.getMessage(), e);
            e.printStackTrace();
        } finally {
            if (cursor != null)
                cursor.close();
        }
        return columns;
    }
}

下面是一个示例,说明如何在DaoMaster.java类中调用它:

@Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.i("greenDAO", "Upgrading schema from version " + oldVersion + " to " + newVersion + " by migrating all tables data");

        MigrationHelper.getInstance().migrate(db,
                UserDao.class,
                ItemDao.class);
    }
Pedro Okawa answered 2019-11-08T09:10:04Z
20 votes

您假设正确。 如今,不同架构版本之间没有更改跟踪。 因此,在升级架构时,您需要自己编写SQL。

Markus Junginger answered 2019-11-08T09:08:26Z
11 votes

这是与@PedroOkawa相同的代码,该代码与GreenDao 3. +一起使用,但存在固定错误:

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.annotation.NonNull;
import android.text.TextUtils;

import org.greenrobot.greendao.AbstractDao;
import org.greenrobot.greendao.database.Database;
import org.greenrobot.greendao.database.StandardDatabase;
import org.greenrobot.greendao.internal.DaoConfig;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * Createdby PedroOkawa and modified by MBH on 16/08/16.
 */
public final class MigrationHelper {

    public static void migrate(SQLiteDatabase sqliteDatabase, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        StandardDatabase db = new StandardDatabase(sqliteDatabase);
        generateNewTablesIfNotExists(db, daoClasses);
        generateTempTables(db, daoClasses);
        dropAllTables(db, true, daoClasses);
        createAllTables(db, false, daoClasses);
        restoreData(db, daoClasses);
    }

    public static void migrate(StandardDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        generateNewTablesIfNotExists(db, daoClasses);
        generateTempTables(db, daoClasses);
        dropAllTables(db, true, daoClasses);
        createAllTables(db, false, daoClasses);
        restoreData(db, daoClasses);
    }

    private static void generateNewTablesIfNotExists(StandardDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        reflectMethod(db, "createTable", true, daoClasses);
    }

    private static void generateTempTables(StandardDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        for (int i = 0; i < daoClasses.length; i++) {
            DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);
            String tableName = daoConfig.tablename;
            String tempTableName = daoConfig.tablename.concat("_TEMP");
            StringBuilder insertTableStringBuilder = new StringBuilder();
            insertTableStringBuilder.append("CREATE TEMP TABLE ").append(tempTableName);
            insertTableStringBuilder.append(" AS SELECT * FROM ").append(tableName).append(";");
            db.execSQL(insertTableStringBuilder.toString());
        }
    }

    private static void dropAllTables(StandardDatabase db, boolean ifExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) {
        reflectMethod(db, "dropTable", ifExists, daoClasses);
    }

    private static void createAllTables(StandardDatabase db, boolean ifNotExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) {
        reflectMethod(db, "createTable", ifNotExists, daoClasses);
    }

    /**
     * dao class already define the sql exec method, so just invoke it
     */
    private static void reflectMethod(StandardDatabase db, String methodName, boolean isExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) {
        if (daoClasses.length < 1) {
            return;
        }
        try {
            for (Class cls : daoClasses) {
                Method method = cls.getDeclaredMethod(methodName, Database.class, boolean.class);
                method.invoke(null, db, isExists);
            }
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }

    private static void restoreData(StandardDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        for (int i = 0; i < daoClasses.length; i++) {
            DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);
            String tableName = daoConfig.tablename;
            String tempTableName = daoConfig.tablename.concat("_TEMP");
            // get all columns from tempTable, take careful to use the columns list
            List<String> columns = getColumns(db, tempTableName);
            ArrayList<String> properties = new ArrayList<>(columns.size());
            for (int j = 0; j < daoConfig.properties.length; j++) {
                String columnName = daoConfig.properties[j].columnName;
                if (columns.contains(columnName)) {
                    properties.add(columnName);
                }
            }
            if (properties.size() > 0) {
                final String columnSQL = TextUtils.join(",", properties);

                StringBuilder insertTableStringBuilder = new StringBuilder();
                insertTableStringBuilder.append("INSERT INTO ").append(tableName).append(" (");
                insertTableStringBuilder.append(columnSQL);
                insertTableStringBuilder.append(") SELECT ");
                insertTableStringBuilder.append(columnSQL);
                insertTableStringBuilder.append(" FROM ").append(tempTableName).append(";");
                db.execSQL(insertTableStringBuilder.toString());
            }
            StringBuilder dropTableStringBuilder = new StringBuilder();
            dropTableStringBuilder.append("DROP TABLE ").append(tempTableName);
            db.execSQL(dropTableStringBuilder.toString());
        }
    }

    private static List<String> getColumns(StandardDatabase db, String tableName) {
        List<String> columns = null;
        Cursor cursor = null;
        try {
            cursor = db.rawQuery("SELECT * FROM " + tableName + " limit 0", null);
            if (null != cursor && cursor.getColumnCount() > 0) {
                columns = Arrays.asList(cursor.getColumnNames());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (cursor != null)
                cursor.close();
            if (null == columns)
                columns = new ArrayList<>();
        }
        return columns;
    }

}

用法是:

@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int oldVersion, int newVersion) {
    MigrationHelper.migrate(new StandardDatabase(sqLiteDatabase),
                UserDao.class,
                ItemDao.class);
    // OR you can use it like this (Dont use both it is example of 2 different usages)
    MigrationHelper.migrate(sqLiteDatabase,
                UserDao.class,
                ItemDao.class);
}

StandardDatabase在greendao中可以找到,这是进口:

import org.greenrobot.greendao.database.StandardDatabase;

再次感谢@PedroOkawa :)

MBH answered 2019-11-08T09:10:55Z
9 votes

我认为我对类似问题的回答可以帮助这种方法。 如果您确实需要迁移数据,我建议您,例如,如果您需要处理一些约束更改或SQLite不支持的事情,请自己编写迁移。 例如,一个迁移助手的示例(按照我对链接响应所做的方法)可能是:

public class DBMigrationHelper6 extends AbstractMigratorHelper {

/* Upgrade from DB schema 6 to schema 7 , version numbers are just examples*/

public void onUpgrade(SQLiteDatabase db) {

    /* Create a temporal table where you will copy all the data from the previous table that you need to modify with a non supported sqlite operation */
    db.execSQL("CREATE TABLE " + "'post2' (" + //
            "'_id' INTEGER PRIMARY KEY ," + // 0: id
            "'POST_ID' INTEGER UNIQUE ," + // 1: postId
            "'USER_ID' INTEGER," + // 2: userId
            "'VERSION' INTEGER," + // 3: version
            "'TYPE' TEXT," + // 4: type
            "'MAGAZINE_ID' TEXT NOT NULL ," + // 5: magazineId
            "'SERVER_TIMESTAMP' INTEGER," + // 6: serverTimestamp
            "'CLIENT_TIMESTAMP' INTEGER," + // 7: clientTimestamp
            "'MAGAZINE_REFERENCE' TEXT NOT NULL ," + // 8: magazineReference
            "'POST_CONTENT' TEXT);"); // 9: postContent

    /* Copy the data from one table to the new one */
    db.execSQL("INSERT INTO post2 (_id, POST_ID, USER_ID, VERSION, TYPE,  MAGAZINE_ID, SERVER_TIMESTAMP, CLIENT_TIMESTAMP, MAGAZINE_REFERENCE, POST_CONTENT)" +
            "   SELECT _id, POST_ID, USER_ID, VERSION, TYPE,  MAGAZINE_ID, SERVER_TIMESTAMP, CLIENT_TIMESTAMP, MAGAZINE_REFERENCE, POST_CONTENT FROM post;");

    /* Delete the previous table */
    db.execSQL("DROP TABLE post");
    /* Rename the just created table to the one that I have just deleted */
    db.execSQL("ALTER TABLE post2 RENAME TO post");

    /* Add Index/es if you want them */
    db.execSQL("CREATE INDEX " + "IDX_post_USER_ID ON post" +
            " (USER_ID);");

   }
}
pleonasmik answered 2019-11-08T09:11:27Z
8 votes

对于那些希望在greenDAO 3上更新数据库架构版本的用户,请将其添加到应用程序的依赖关系上方的2604941335195095026432文件中:

apply plugin: 'org.greenrobot.greendao'

greendao {
    schemaVersion 1
}
Codelicious answered 2019-11-08T09:11:55Z
1 votes

Pedro Okawa的解决方案是正确的,但是您需要编写“ UpgradeHelper”以扩展“ OpenHelper”,因为每次重新生成DAO代码时,DaoMaster都会被覆盖。

例:

public class UpgradeHelper extends DaoMaster.OpenHelper {

public UpgradeHelper(Context context, String name, SQLiteDatabase.CursorFactory factory) {
    super(context, name, factory);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    Log.i("greenDAO", "Upgrading schema from version " + oldVersion + " to " + newVersion + " by migrating all tables data");

    MigrationHelper.getInstance().migrate(db,
            UserDao.class,
            ItemDao.class,
            AnotherClassToGenerateDao.class);
}

}

oskarko answered 2019-11-08T09:12:26Z
0 votes

如果您只是想在不删除用户数据的情况下向架构中添加新表并且不需要转换任何现有数据的方法,请查看我对此问题的回答,以获取有关如何使用它的离散示例。 绿岛

DiscDev answered 2019-11-08T09:12:51Z
translate from https://stackoverflow.com:/questions/13373170/greendao-schema-update-and-data-migration