ActiveAndroid 与 Cascade 的一对多关系

Question

我有点困惑如何创建Model 和ActiveAndroid 以拥有两个与Cascade 条件onDelete 相关的表，并且找不到任何好的/清晰的示例来学习。 所以我有这张桌子：

    @Table(name = "CheckList")
    public class CheckList {

    @Column(name = "Title")
    String Title;
    @Column(name = "After")
    Integer After;
    @Column(name = "Before")
    Integer Before;

    @Column(name = "Enabled")
    Boolean Enabled;

    @Column(name = "Info")
    String Info;
}

我需要在这个表中列出它：

@Table(name = "Equipment")
public class Equipment {

    @Column(name = "Title")
    String Title;

    @Column(name = "Checklists")
    List<CheckList> Checklists;

}

我也可能有另一个表，其中包含Equipment 列表，我需要像上面那样关联它们。

我想要的是，当我从Equipment 中删除一条记录时，我需要将List<CheckList> Checklists; 中与此Equipment 相关的所有记录也删除。我知道我可以进行查询等，但我需要知道是否有更好的方法和正确的方法来做到这一点？

请详细说明（稍后如何创建关系和查询）并展示与我的表相关的示例。

Answer 1

您需要设置具有外键级联关系的表。

@Table(name = "Equipment")
public class Equipment {

    @Column(name = "Title")
    String Title;

    // This method is optional & does not affect the foreign key creation.
    public List<CheckList> items() {
        return getMany(CheckList.class, "Equipment");
    }
}

@Table(name = "CheckList")
public class CheckList {

    @Column(name = "Title")
    String Title;

    @Column(name = "After")
    Integer After;

    @Column(name = "Before")
    Integer Before;

    @Column(name = "Enabled")
    Boolean Enabled;

    @Column(name = "Info")
    String Info;

    //This establishes a relationship between Checklist and Equipment, Any update or delete operations done on Equipment table gets cascaded to the corresponding rows in the Checklist table.
    @Column(name = "Equipment", onUpdate = ForeignKeyAction.CASCADE, onDelete = ForeignKeyAction.CASCADE)
    Equipment equipment;

}

---

参考资料：

1. Reference article
2. Possible values for ForeignKeyAction
3. Official docs with basics on how to set up relationships & models
4. Closed issue that confirms that CASCADE DELETE works