Question

这是我的Realm数据库的结构：

    public class ARDatabase extends RealmObject
    {
    @PrimaryKey
    private String uid;

    private String namex;
    private String desc;
    private boolean isVideo;
    private boolean isDeleted;
    private String urlImg;
    private String urlApp;
    private int updates;
    private boolean isDownloaded;
    private String location;

    public ARDatabase(){}

    public String getUid()
    {
        return uid;
    }

    public void setUid(String uid)
    {
        this.uid = uid;
    }

    public String getNamex()
    {
        return namex;
    }

    public void setNamex(String namex)
    {
        this.namex = namex;
    }

    public String getDesc()
    {
        return desc;
    }

    public void setDesc(String desc)
    {
        this.desc = desc;
    }

    public boolean getIsVideo()
    {
        return isVideo;
    }

    public void setIsVideo(boolean isVideo)
    {
        this.isVideo = isVideo;
    }

    public boolean getIsDeleted()
    {
        return isDeleted;
    }

    public void setIsDeleted(boolean isDeleted)
    {
        this.isDeleted = isDeleted;
    }

    public String getUrlImg()
    {
        return urlImg;
    }

    public void setUrlImg(String urlImg)
    {
        this.urlImg = urlImg;
    }

    public String getUrlApp()
    {
        return urlApp;
    }

    public void setUrlApp(String urlApp)
    {
        this.urlApp = urlApp;
    }

    public int getUpdates()
    {
        return updates;
    }

    public void setUpdates(int updates)
    {
        this.updates = updates;
    }

    public boolean getIsDownloaded()
    {
        return isDownloaded;
    }

    public void setIsDownloaded(boolean isDownloaded)
    {
        this.isDownloaded = isDownloaded;
    }

    public String getLocation()
    {
        return location;
    }

    public void setLocation(String location)
    {
        this.location = location;
    }
    }

我可以成功地将对象添加到数据库中当我需要更新对象时会出现问题。

这就是我的尝试：

private void downloadUpdateDatabase(String uid,String location_address) throws RealmException
{

    mRealm.beginTransaction();
    ARDatabase db = new ARDatabase();
    db.setUid(uid);
    db.setIsDownloaded(true);
    db.setLocation(location_address);
    mRealm.copyToRealmOrUpdate(db);
    mRealm.commitTransaction();
    Log.e("TAG","DOWNLOAD UPDATE COMPLETED");

}

这里的问题是我调用此方法时。提到的字段会更新，但此方法中未提及的字段将变为null或零当然，我可以通过调用它们的setter来设置所有字段的值，但是从我调用此方法的地方，我无法获得所有字段值。

所以，问题是：如何以现有字段不变为空的方式更新我的领域数据库？

P.S：

My Realm版本为：0.84.1，compile 'io.realm:realm-android:0.84.1'

Answer 1

提到的字段会更新，但此方法中未提及的字段将变为null或零

嗯，是的，此时所有字段都是默认值。

ARDatabase db = new ARDatabase();

您是否尝试过查询当前记录，然后更新字段，然后将该对象放回去？

换句话说，你有String uid，所以像

private void downloadUpdateDatabase(String uid,String location_address) throws RealmException
{
    mRealm.beginTransaction();
    ARDatabase db = mRealm.where(ARDatabase.class).equalTo("uid", uid).findFirst();
    db.setIsDownloaded(true);
    db.setLocation(location_address);
    mRealm.copyToRealmOrUpdate(db);
    mRealm.commitTransaction();
}

或者，probably better in async fashion。

private void downloadUpdateDatabase(final String uid, final String location_address) throws RealmException
{
    mRealm.executeTransactionAsync(new Realm.Transaction() {
        @Override
        public void execute(Realm realm) {
            ARDatabase db = realm.where(ARDatabase.class).equalTo("uid", uid).findFirst();
            db.setIsDownloaded(true);
            db.setLocation(location_address);
        }
    }, new Realm.Transaction.OnSuccess() {
        @Override
        public void onSuccess() {
            // Transaction was a success.
        }
    }, new Realm.Transaction.OnError() {
        @Override
        public void onError(Throwable error) {
            // Transaction failed and was automatically canceled.
        }
    });
}

Answer 2

而不是

mRealm.beginTransaction();
ARDatabase db = new ARDatabase();
db.setUid(uid);
db.setIsDownloaded(true);
db.setLocation(location_address);
mRealm.copyToRealmOrUpdate(db);
mRealm.commitTransaction();
Log.e("TAG","DOWNLOAD UPDATE COMPLETED");

应该有

mRealm.executeTransaction(new Realm.Transaction() {
    @Override
    public void execute(Realm realm) {
        ARDatabase db = realm.where(ARDatabase.class).equalTo("uid", uid).findFirst();
        if(db == null) {
            db = realm.createObject(ARDatabase.class, uid);
        }
        db.setIsDownloaded(true);
        db.setLocation(location_address);
    }
});
Log.e("TAG","DOWNLOAD UPDATE COMPLETED");

更新Realm数据库的正确方法？

2 个答案: