从父节点读取特定叶/子节点的Firebase规则

我的firebase数据库如下所示

"students" : {
  "firebase_key_1" : {
    "Name" : "blah blah",
    "Address" : "blah blah",
    "Roll No" : "blah blah",
    "Marks" : {
        "Sub1" : "blah",
        "Sub2" : "blah",
        "Sub3" : "blah",
        "Total" : "Total",
    },
    "class" : "blah blah",
    "Transportation" : "blah blah",
    "Department" : "blah blah",
},
  "firebase_key_2" : {
    "Name" : "blah blah",
    "Address" : "blah blah",
    "Roll No" : "blah blah",
    "Marks" : {
        "Sub1" : "blah",
        "Sub2" : "blah",
        "Sub3" : "blah",
        "Total" : "Total",
    },
    "class" : "blah blah",
    "Transportation" : "blah blah",
    "Department" : "blah blah",
},
  "firebase_key_3" : {
    "Name" : "blah blah",
    "Address" : "blah blah",
    "Roll No" : "blah blah",
    "Marks" : {
        "Sub1" : "blah",
        "Sub2" : "blah",
        "Sub3" : "blah",
        "Total" : "Total",
    },
    "class" : "blah blah",
    "Transportation" : "blah blah",
    "Department" : "blah blah",
}
}

我正在使用RESTAPI从firebase检索数据。Restapi url看起来像“Marks/Total”&startAt=400

我已经通过firebase规则对学生总数进行了索引。我得到的结果和额外的数据，如姓名，班级，卷号

我希望输出是

    "firebase_key_1" : {
    "Marks" : {
        "Sub1" : "blah",
        "Sub2" : "blah",
        "Sub3" : "blah",
        "Total" : "Total",
    }
},
"firebase_key_2" : {
    "Marks" : {
        "Sub1" : "blah",
        "Sub2" : "blah",
        "Sub3" : "blah",
        "Total" : "Total",
    }
},
"firebase_key_3" : {
    "Marks" : {
        "Sub1" : "blah",
        "Sub2" : "blah",
        "Sub3" : "blah",
        "Total" : "Total",
    }
}

是否有通过RestAPi或规则来实现这一点

例如，我们是否有任何规则可以定义要读取的节点

{
 "users":{
   "students":{
      ".read" : ["$firebaseKey/Marks"],
      ".write" : true,
   }
   }

因此，我可以使用RESTAPI从父节点检索所需的值

任何其他这样做的建议都会很好

---

提前感谢

Firebase数据库始终返回完整的节点。不可能获得与查询匹配的每个节点的子集。要么返回整个节点，要么不返回

通常，这种类型的请求表示您已经合并了多个应该分离的数据类型。在您的情况下，看起来应该有两个顶级集合：

students

和

studentMarks

。在

students

下，您保留每个学生的属性，由其学生ID键入。在

studentMarks

下，您保留每个学生的标记，再次由其学生ID键入

因此：

---

由于您在

学生

和

学生分数

之间使用相同的键，因此您可以轻松地为用户准备这两组数据。但是现在，您也可以只读取每个用户的属性，或者只读取一组用户的标记。

我不明白您在这里想要实现什么。您是否可以编辑您的问题以显示：1）您要执行的REST调用，2）该位置的JSON（作为文本），3）您希望从调用返回的结果？我已编辑了上述问题。这不是规则的有效语法：

。请阅读：“$firebaseKey/Marks”]

。非常感谢，我将改变结构。我认为会有这样的语法“.read”：[“$firebaseKey/Marks”]。与indexOn相似，这就是为什么我认为我可以坚持这种结构。无论如何，非常感谢。

"students" : {
  "firebase_key_1" : {
    "Name" : "blah blah",
    "Address" : "blah blah",
    "Roll No" : "blah blah",
    "class" : "blah blah",
    "Transportation" : "blah blah",
    "Department" : "blah blah",
  },
  "firebase_key_2" : {
    "Name" : "blah blah",
    "Address" : "blah blah",
    "Roll No" : "blah blah",
    "class" : "blah blah",
    "Transportation" : "blah blah",
    "Department" : "blah blah",
  },
  "firebase_key_3" : {
    "Name" : "blah blah",
    "Address" : "blah blah",
    "Roll No" : "blah blah",
    "class" : "blah blah",
    "Transportation" : "blah blah",
    "Department" : "blah blah",
  }
},
"studentMarks": 
  "firebase_key_1" : {
    "Sub1" : "blah",
    "Sub2" : "blah",
    "Sub3" : "blah",
    "Total" : "Total",
  },
  "firebase_key_2" : {
    "Sub1" : "blah",
    "Sub2" : "blah",
    "Sub3" : "blah",
    "Total" : "Total",
  },
  "firebase_key_3" : {
    "Sub1" : "blah",
    "Sub2" : "blah",
    "Sub3" : "blah",
    "Total" : "Total",
  }
}