android - onDelete = NO_ACTION 导致错误 : "SQLiteConstraintException: FOREIGN KEY constraint failed" (code 787)

Question

我在 SQLite for Android 上使用 Room，我有以下两个 Pojo 实体:

@Entity
public class Event {
    @PrimaryKey
    @NonNull
    private String eventId;
    private String eventName;
}

@Entity(primaryKeys = {"eventId","attendeeId"},
        foreignKeys = {
                @ForeignKey(entity = Event.class,
                        parentColumns = "eventId",
                        childColumns = "eventId" ,onDelete = NO_ACTION)
        })
public class Attendee {
    @NonNull
    private String eventId;
    @NonNull
    private String attendeeId;
}

当我尝试从事件表中删除记录时，我收到以下错误:

Caused by: android.database.sqlite.SQLiteConstraintException: FOREIGN KEY constraint failed (code 787) at android.database.sqlite.SQLiteConnection.nativeExecuteForChangedRowCount(Native Method)
        at android.database.sqlite.SQLiteConnection.executeForChangedRowCount(SQLiteConnection.java:732)
        at android.database.sqlite.SQLiteSession.executeForChangedRowCount(SQLiteSession.java:754)
        at android.database.sqlite.SQLiteStatement.executeUpdateDelete(SQLiteStatement.java:64)
        at android.arch.persistence.db.framework.FrameworkSQLiteStatement.executeUpdateDelete(FrameworkSQLiteStatement.java:45)
        at com.minapharm.hixspro.POJO.Room.Events.EventDao_Impl.deleteTable(EventDao_Impl.java:168)

但是，如果我将 onDelete 更改为 CASCADE，则不会出现问题!

我错过了什么吗？

Answer 1

如果你会看到 here .

By default, NO_ACTION is used.

您无需明确提供。

@Entity(primaryKeys = {"eventId","attendeeId"},
        foreignKeys = {
                @ForeignKey(entity = Event.class,
                        parentColumns = "eventId",
                        childColumns = "eventId")
        })
public class Attendee {
    @NonNull
    private String eventId;
    @NonNull
    private String attendeeId;
}

此外，您需要了解数据库是创建一次的。您应该重新安装应用程序，然后检查删除是否有效。

已编辑:由于您已定义 ForeignKey 但未定义 onDelete CASCADE，因此您必须手动从 Attendee 中删除所有指向 Event Table 行的条目 - 您正在删除。