Kamar - Menggunakan SQLite eksternal serta DB internal

Yang kami butuhkan:

Kita harus dapat menggunakan melampirkan database eksternal ke Database Kamar internal tanpa mengubah jalur penyimpanannya. Setelah menambahkannya, kita ingin dapat menggunakan database dengan objek Entitas Kamar, Dao, dan Database. Apakah ada cara yang mungkin untuk mencapai ini?

Mungkin lebih mudah untuk tidak melampirkan, alasannya adalah Anda dapat menggunakan instance Room Database yang terpisah. Tanpa Anda harus memiliki DAO terpisah untuk memenuhi nama skema terlampir (saya percaya). Mengatakan bahwa contoh di bawah (berdasarkan sesuatu yang saya mainkan untuk seseorang dan karenanya nama kolom yang agak membingungkan) .

misalnya dengan asumsi ATTACH DATABASE .... AS other (skema terlampir adalah lainnya ) kemudian alih-alih (untuk database utama)

@Query("SELECT * FROM AllUsers")
List<AllUsers> getAllAllUsers();

Anda akan membutuhkan gratis :-

@SkipQueryVerification
@Query("SELECT * FROM other.AllUsers")
List<AllUsers> getOtherAllAllUsers();

dll.

Namun, jika Anda malah memiliki sesuatu seperti (untuk utama):-

    mLPDB = Room.databaseBuilder(this,LoanPaymentDatabase.class,"mydb").allowMainThreadQueries().build();
    mLPDB_DAO = mLPDB.mDao();

Bersama (untuk yang lain) :-

    mOtherDB = Room.databaseBuilder(this,LoanPaymentDatabase.class,OtherDatabaseHelper.DBNAME).allowMainThreadQueries().build();
    mOtherDAO = mOtherDB.mDao();

Kemudian Anda dapat mengakses keduanya menggunakan DAO yang sama.

Catatan tentu saja di atas mengasumsikan bahwa skema tersebut saling melengkapi (belum tentu tepat).

Belum tentu tepat?

Juga meliputi komentar :-

Anda harus memigrasikan data ke ruangan itu sendiri terlebih dahulu.

Dengan sedikit bermain, Anda dapat mengatasi harus bermigrasi dengan membodohi room dengan menyetel user_version ke 0. Dalam hal ini Room menyetel nomor versi (pengujian terbatas). Namun, saya tidak yakin apa yang akan dilakukan GreenDao atau Server Anda (pekerjaan rumah Anda).
Pengujian terbatas saya adalah untuk masalah umum ketika memigrasikan kolom dengan INTEGER PRIMARY KEY yaitu tanpa AUTOINCREMENT. Kamar jika bermigrasi akan mengeluh bahwa skema tidak cocok. Jadi saya sengaja tidak mengkode AUTOINCREMENT, mengatur user_version ke 0 dan tidak ada keluhan mengakses database melalui Room. Juga menggunakan jenis kolom rumlestilskin dan tidak ada keluhan.

Karena itu saya percaya bahwa Anda dapat mengatasi masalah migrasi dengan yang diharapkan/ditemukan yang ditakuti dengan mengatur user_version ke 0 (dan karenanya saya percaya menghindari migrasi). Jelas meskipun nama kolom harus cocok, jika didefinisikan dalam Entitas dan tidak diabaikan.

Saya juga mencoba menambahkan kolom yang tidak mendefinisikan Entitas dan menggunakan hasil di atas tanpa keluhan (pengujian ini harus terlihat jelas pada kode di bawah).

Contoh

Berikut ini adalah contoh Database 2 Entity Room dan untuk keperluan pengujian lainnya database yang dibangun di luar ruangan yang cukup cocok dengan database ruangan untuk dapat digunakan yaitu nama kolom entitas dicocokkan.

Basis data lainnya

Basis data non-ruangan lainnya dibuat melalui SQLiteOpenHelper subkelas sesuai OtherDatabaseHelper.java :-

public class OtherDatabaseHelper extends SQLiteOpenHelper {

    public static final String DBNAME = "lpolddb";
    public static final int DBVERSION = 1;
    public static final String ALLUSERS_TBL = "AllUsers";
    public static final String PAIDUNPAID_TBL = "PaidUnpaid";

    /*
        @PrimaryKey(autoGenerate = true)
        private long auid;
        private String Name;
        private int Loan;
        private int TimeInMonths;
     */
    public static final String ALLUSERS_COL_AUID = "auid";
    public static final String ALLUSERS_COL_NAME = "Name";
    public static final String ALLUSERS_COL_LOAN = "Loan";
    public static final String ALLUSERS_COL_TIMEINMONTHS = "TimeInMonths";

    private static final String crt_allusers_table_sql =
            "CREATE TABLE IF NOT EXISTS " + ALLUSERS_TBL + "(" +
                    //ALLUSERS_COL_AUID + " INTEGER PRIMARY KEY AUTOINCREMENT," +
                    ALLUSERS_COL_AUID + " INTEGER PRIMARY KEY," +
                    ALLUSERS_COL_NAME + " TEXT, " +
                    ALLUSERS_COL_LOAN + " INTEGER, " +
                    "someothercolumnnotdefineinroom TEXT, " + //!!!!!!!!!! not a column in an entity
                    ALLUSERS_COL_TIMEINMONTHS + " INTEGER" +
                    ")";

    /*
        @PrimaryKey(autoGenerate = true)
        private long puid;
        private int TimeInMonths;
        private String PaidUnpaid;
        @ForeignKey(
            entity = AllUsers.class,
            parentColumns = {"auid"},
            childColumns = {"AllUsersReference"},
            onUpdate = ForeignKey.CASCADE, onDelete = ForeignKey.CASCADE)
        private long AllUsersReference;
     */

    public static final String PAIDUNPAID_COL_PUID = "puid";
    public static final String PAIDUNPAID_TIMEINMONTHS = ALLUSERS_COL_TIMEINMONTHS;
    public static final String PAIDUNPAID_COL_PAIDUNPAID = "PaidUnpaid";
    public static final String PAIDUNPAID_COL_ALLUSERSREFERENCE = "AllUsersReference";

    public static final String crt_paidunpaid_table_sql =
            "CREATE TABLE IF NOT EXISTS " + PAIDUNPAID_TBL + "(" +
                    PAIDUNPAID_COL_PUID + " INTEGER PRIMARY KEY AUTOINCREMENT," +
                    PAIDUNPAID_TIMEINMONTHS + " rumplestilskin, " + // !!!!!!!!!!!
                    PAIDUNPAID_COL_PAIDUNPAID + " TEXT," +
                    PAIDUNPAID_COL_ALLUSERSREFERENCE + " INTEGER " +
                    " REFERENCES " + ALLUSERS_TBL + "(" + ALLUSERS_COL_AUID + ") " +
                    "ON UPDATE CASCADE ON DELETE CASCADE" +
                    ")";


    SQLiteDatabase mDB;
    public OtherDatabaseHelper(Context context) {
        super(context, DBNAME, null, DBVERSION);
        mDB = this.getWritableDatabase();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(crt_allusers_table_sql);
        db.execSQL(crt_paidunpaid_table_sql);
    }

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

    }

    public long insertAllUsers(String name, int loanamount, int periodofloan) {
        ContentValues cv = new ContentValues();
        cv.put(ALLUSERS_COL_NAME,name);
        cv.put(ALLUSERS_COL_LOAN,loanamount);
        cv.put(ALLUSERS_COL_TIMEINMONTHS,periodofloan);
        return mDB.insert(ALLUSERS_TBL,null,cv);
    }

    public long insertPaidUnpaid(int formonth, String status, long allUserreferenced) {
        ContentValues cv = new ContentValues();
        cv.put(PAIDUNPAID_TIMEINMONTHS,formonth);
        cv.put(PAIDUNPAID_COL_PAIDUNPAID,status);
        cv.put(PAIDUNPAID_COL_ALLUSERSREFERENCE,allUserreferenced);
        return mDB.insert(PAIDUNPAID_TBL,null,cv);
    }
}

lihat komentar untuk keanehan/perbedaan yang sengaja ditambahkan
ini diisi, diakses oleh database Room alternatif dan melalui DB terlampir di MainActivity.java di bawah

Database Kamar

2 Entitas :-

AllUsers.java

@Entity
public class AllUsers {
    @PrimaryKey(autoGenerate = true)
    private long auid;
    private String Name;
    private int Loan;
    private int TimeInMonths;

    public AllUsers() {
    }

    @Ignore
    public AllUsers(String Name, int Loan, int TimeInMonths) {
        this.Name = Name;
        this.Loan = Loan;
        this.TimeInMonths = TimeInMonths;
    }

    public long getAuid() {
        return auid;
    }

    public void setAuid(long auid) {
        this.auid = auid;
    }

    public String getName() {
        return Name;
    }

    public void setName(String name) {
        Name = name;
    }

    public int getLoan() {
        return Loan;
    }

    public void setLoan(int loan) {
        Loan = loan;
    }

    public int getTimeInMonths() {
        return TimeInMonths;
    }

    public void setTimeInMonths(int timeInMonths) {
        TimeInMonths = timeInMonths;
    }
}

dan PaidUnpaid.java :-

@Entity
public class PaidUnpaid {
    @PrimaryKey(autoGenerate = true)
    private long puid;
    private int TimeInMonths;
    private String PaidUnpaid;
    @ForeignKey(
            entity = AllUsers.class,
            parentColumns = {"auid"},
            childColumns = {"AllUsersReference"},
            onUpdate = ForeignKey.CASCADE, onDelete = ForeignKey.CASCADE)
    private long AllUsersReference;


    public PaidUnpaid() {
    }

    @Ignore
    public PaidUnpaid(int TimeInMonths, String PaidUnpaid, long AllUsersreference) {
        this.TimeInMonths = TimeInMonths;
        this.PaidUnpaid = PaidUnpaid;
        this.AllUsersReference = AllUsersreference;
    }

    public long getPuid() {
        return puid;
    }

    public void setPuid(long puid) {
        this.puid = puid;
    }

    public int getTimeInMonths() {
        return TimeInMonths;
    }

    public void setTimeInMonths(int timeInMonths) {
        TimeInMonths = timeInMonths;
    }

    public String getPaidUnpaid() {
        return PaidUnpaid;
    }

    public void setPaidUnpaid(String paidUnpaid) {
        PaidUnpaid = paidUnpaid;
    }

    public long getAllUsersReference() {
        return AllUsersReference;
    }

    public void setAllUsersReference(long allUsersReference) {
        AllUsersReference = allUsersReference;
    }
}

Kelas POJO tambahan, AllUsersAndPaidUnpaidsList.java yang dimainkan dengan begitu tergabung dan digunakan :-

public class AllUsersAndPaidUnpaidsList {

    @Embedded
    AllUsers allUsers;
    @Ignore
    @PrimaryKey
    long auid;

    @Ignore
    @Relation(entity = PaidUnpaid.class,parentColumn = "auid",entityColumn = "puid")
    List<PaidUnpaid> paidUnpaidList;

    @Ignore
    public AllUsersAndPaidUnpaidsList(AllUsers au, List<PaidUnpaid> pulist) {
        this.allUsers = au;
        this.paidUnpaidList = pulist;
    }

    public List<PaidUnpaid> getPaidUnpaidList() {
        return this.paidUnpaidList;
    }


    public void setPaidUnpaidList(List<PaidUnpaid> paidUnpaidList) {
        this.paidUnpaidList = paidUnpaidList;
    }

    public AllUsers getAllUsers() {
        return allUsers;
    }

    public void setAllUsers(AllUsers allUsers) {
        this.allUsers = allUsers;
    }

    public void outputToLog(String tag) {
        StringBuilder sb = new StringBuilder("AllUsersName = ")
                .append(this.allUsers.getName())
                .append(" TimeInMonths = ")
                .append(String.valueOf(this.allUsers.getTimeInMonths()))
                ;
        for (PaidUnpaid pu: this.getPaidUnpaidList()) {
            sb.append("\n\t TimeInMonths = ")
                    .append(String.valueOf(pu.getTimeInMonths()))
                    .append(" Paid/Unpaid = ")
                    .append(pu.getPaidUnpaid());
        }
        Log.d(tag,sb.toString());
    }
}

Antarmuka tunggal Dao.java :-

@androidx.room.Dao
public interface Dao {

    @Insert(onConflict = OnConflictStrategy.IGNORE)
    long[] insertAllUsers(AllUsers... allUsers);

    @Insert(onConflict = OnConflictStrategy.IGNORE)
    long insertAllUsers(AllUsers allUsers);

    @Insert(onConflict = OnConflictStrategy.IGNORE)
    long[] insertPaidUnpaid(PaidUnpaid... paidUnpaids);

    @Insert(onConflict = OnConflictStrategy.IGNORE)
    long insertPaidUnpaid(PaidUnpaid paidUnpaid);

    @Update(onConflict = OnConflictStrategy.IGNORE)
    int updateAllUsers(AllUsers... allUsers);

    @Update(onConflict =  OnConflictStrategy.IGNORE)
    int updateAllUsers(AllUsers allUsers);

    @Update(onConflict = OnConflictStrategy.IGNORE)
    int updatePaidUnpaid(PaidUnpaid... paidUnpaids);

    @Update(onConflict = OnConflictStrategy.IGNORE)
    int updatePaidUnpaid(PaidUnpaid paidUnpaid);

    @Delete
    int deleteAllUsers(AllUsers... allUsers);

    @Delete
    int deleteAllUsers(AllUsers allUsers);

    @Delete
    int deletePaidUnpaid(PaidUnpaid... paidUnpaids);

    @Delete
    int deletePaidUnpaid(PaidUnpaid paidUnpaid);

    @Query("SELECT * FROM AllUsers")
    List<AllUsers> getAllAllUsers();

    @Query("SELECT * FROM AllUsers WHERE auid = :id")
    List<AllUsers> getOneAllUsersById(long id);

    @Query("SELECT * FROM PaidUnpaid")
    List<PaidUnpaid> getAllPaidUnpaids();

    @Query("SELECT * FROM PaidUnpaid WHERE puid = :id")
    List<PaidUnpaid> getOnePaidUnpaidById(long id);

    @Query("SELECT * FROM PaidUnpaid WHERE AllUsersReference = :allUsersid")
    List<PaidUnpaid> getPaidUnpaidsForAllUsersId(long allUsersid);

    /*************
     * Some Additional DAO's for attached not required for alternative helper
     * in practice you would likely need attached versions of all
     ************/

    @Query("SELECT * FROM other.PaidUnpaid WHERE AllUsersReference = :allUsersid")
    @SkipQueryVerification
    List<PaidUnpaid> getOtherPaidUnpaidForAllUsersId(long allUsersid);

    @SkipQueryVerification
    @Query("SELECT * FROM other.AllUsers")
    List<AllUsers> getOtherAllAllUsers();
}

Kelas Database Kamar LoanPaymentDatabase.java

@Database(entities = {AllUsers.class,PaidUnpaid.class},exportSchema = false,version = 1)
public abstract class LoanPaymentDatabase extends RoomDatabase {
    public abstract Dao mDao();
}

Menggabungkan semuanya

Akhirnya ada kegiatan yang :-

Membuat dan mengisi lainnya (non-kamar) database (jika tidak ada) untuk pengujian. Menyetel versi_pengguna (versi basis data di Android talk) ke 0.
Membuat, jika perlu, database versi Room.
Menambahkan beberapa baris ke versi Kamar.
Mengeluarkan data dalam versi Room ke log.
Membuat RoomDatabase alternatif menggunakan lainnya basis data.
Mengeluarkan data di lainnya database melalui Kamar.
Lampirkan lainnya database ke versi Kamar.
Mengeluarkan data dari keduanya melalui Roomdatabase asli yang mengakses lainnya . terlampir database melalui antarmuka DAO tambahan yang menyertakan lainnya.???? .

MainActivity.java

public class MainActivity extends AppCompatActivity {

    LoanPaymentDatabase mLPDB;
    Dao mLPDB_DAO;

    LoanPaymentDatabase mOtherDB;
    Dao mOtherDAO;
    Random rnd = new Random();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        manageOtherDatabase();

        mLPDB = Room.databaseBuilder(this,LoanPaymentDatabase.class,"mydb").allowMainThreadQueries().build();
        mLPDB_DAO = mLPDB.mDao();
        // Add some(2) AllUsers
        mLPDB_DAO.insertAllUsers(new AllUsers("Fred",5000,5));
        mLPDB_DAO.insertAllUsers(new AllUsers("Mary", 4000,6));

        // Add Some PaidUnpaid's for each AllUsers
        // Random amount with random paid or unpaid
        // This is just for demonstration and doesn't reflect what would typically be done
        List<AllUsers> allusers =  mLPDB_DAO.getAllAllUsers();
        for (AllUsers au: allusers) {
            int lc = rnd.nextInt(4) + 1;
            int month = 1;
            for (int i=0; i < lc; i++) {
                String paid = "Paid";
                if((rnd.nextInt(2) % 2) > 0 ) {
                    paid = "Unpaid";
                }
                mLPDB_DAO.insertPaidUnpaid(new PaidUnpaid(month++, paid, au.getAuid()));
            }
        }

        //Extract all AllUsersAndPaidUnpaid (i.e  each AllUsers with the related PaidUnpaid for the AllUsers)
        ArrayList<AllUsersAndPaidUnpaidsList> aupulist = new ArrayList<>();
        for (AllUsers au: allusers) {
            List<PaidUnpaid> pulist = mLPDB_DAO.getPaidUnpaidsForAllUsersId(au.getAuid());
            aupulist.add(new AllUsersAndPaidUnpaidsList(au,pulist));
        }

        // Output the results
        for (AllUsersAndPaidUnpaidsList aupu: aupulist) {
            aupu.outputToLog("INITALAUPU");
        }

        //Use separate openHelper rather than ATTACH
        mOtherDB = Room.databaseBuilder(this,LoanPaymentDatabase.class,OtherDatabaseHelper.DBNAME).allowMainThreadQueries().build();
        mOtherDAO = mOtherDB.mDao();
        ArrayList<AllUsersAndPaidUnpaidsList> otheraupulist = new ArrayList<>();
        for (AllUsers oau: mOtherDAO.getAllAllUsers() ) {
            otheraupulist.add(new AllUsersAndPaidUnpaidsList(oau,mOtherDAO.getPaidUnpaidsForAllUsersId(oau.getAuid())));
        }
        for (AllUsersAndPaidUnpaidsList aupu: otheraupulist) {
            aupu.outputToLog("ALTDBAUPU");
        }

        // User Attach
        SupportSQLiteDatabase main_sdb = mLPDB.getOpenHelper().getWritableDatabase();
        SupportSQLiteDatabase other_sdb = mOtherDB.getOpenHelper().getWritableDatabase();
        main_sdb.execSQL("ATTACH DATABASE '" + other_sdb.getPath() + "' AS other");
        ArrayList<AllUsersAndPaidUnpaidsList> attachaupulist = new ArrayList<>();
        for (AllUsers aau: mLPDB_DAO.getAllAllUsers()) {
            attachaupulist.add(new AllUsersAndPaidUnpaidsList(aau,mLPDB_DAO.getPaidUnpaidsForAllUsersId(aau.getAuid())));
        }
        for (AllUsers aauother: mLPDB_DAO.getOtherAllAllUsers()) {
            attachaupulist.add(new AllUsersAndPaidUnpaidsList(aauother,mLPDB_DAO.getOtherPaidUnpaidForAllUsersId(aauother.getAuid())));
        }
        for (AllUsersAndPaidUnpaidsList aupu: attachaupulist) {
            aupu.outputToLog("ATTACHEDAUPU");
        }

        mLPDB.close();
    }

    /*********
     *  For testing purposes - Populate the OTHER database to be used
     *********/
    private void manageOtherDatabase() {
        OtherDatabaseHelper mODBHlpr = new OtherDatabaseHelper(this);
        SQLiteDatabase db = mODBHlpr.getWritableDatabase();
        db.execSQL("PRAGMA user_version = 0");
        if (DatabaseUtils.queryNumEntries(db,OtherDatabaseHelper.ALLUSERS_TBL) > 0) {
            db.close();
            mODBHlpr.close();
            return;
        }
        db.beginTransaction();
        for (int i= 0; i < 5; i++) {
            long auid = mODBHlpr.insertAllUsers("AU" + String.valueOf(i),10000 + 1,5 + i);
            for(int ii = 0; ii < 5; ii++) {
                mODBHlpr.insertPaidUnpaid(ii,"Paid",auid);
            }
        }
        db.setTransactionSuccessful();
        db.endTransaction();
        db.close();
        mODBHlpr.close();
    }
}