Realm 以高效的方式删除孤立对象

Question

我有一个 class BeaconBase 包含 BeaconData 列表。

public class BeaconBase extends RealmObject {

    @PrimaryKey
    private Integer checkInID;

    @SerializedName("beacons")
    @Expose
    private RealmList<BeaconData> beacons;
}

public class BeaconData extends RealmObject {

    @SerializedName("scanId")
    @Expose
    private String scanId;

    @SerializedName("distance")
    @Expose
    private String distance;

}

BeaconData 通常会很大。可能是每小时 100000 行左右。删除相关BeaconBase记录时如何高效删除BeaconData？

我只有 BeaconBase 有主键。

所以当我删除 BeaconBase 记录时，数以千计的 BeaconData 记录被孤立。我怎样才能有效地处理这种情况？

Answer 1

try(Realm r = Realm.getDefaultInstance)) {
    r.executeTransaction((realm) -> {
        RealmResults<BeaconBase> beaconsToDelete = realm.where(BeaconBase.class)./*query here*/.findAll();
        for(int i = beaconsToDelete.size() - 1; i >= 0; i--) {
            BeaconBase beaconBase = beaconsToDelete.get(i);
            beaconBase.getBeacons().deleteAllFromRealm();
            beaconBase.deleteFromRealm();
        }
    });
}

虽然稍微有点用处，但你也可以这样做：

public class BeaconBase extends RealmObject {

    @PrimaryKey
    private Integer checkInID;

    @SerializedName("beacons")
    @Expose
    private RealmList<BeaconData> beacons;
}

public class BeaconData extends RealmObject {

    @SerializedName("scanId")
    @Expose
    private String scanId;

    @SerializedName("distance")
    @Expose
    private String distance;

    @LinkingObjects("beacons")
    private final RealmResults<BeaconBase> beaconDataOf = null;
}

try(Realm r = Realm.getDefaultInstance)) {
    r.executeTransaction((realm) -> {
        realm.where(BeaconBase.class)./*query here*/.findAll().deleteAllFromRealm();
        realm.where(BeaconData.class).isEmpty("beaconDataOf").findAll().deleteAllFromRealm();
    });
}