Firebase查询我正在查找的键/值对位于未知引用下

以下是我要查询的Firebase参考结构:

- someData
    -KgWw4iasffsD-vht3QA   <=== Firebase generated key
        - fieldA: '12345'
        - fieldB: 'here it is'

我想查询,关键例如.fieldB,并测试其值.例如.fieldB ='那里是'

这是我尝试但我的语法错误:

var theRef = firebase.database().ref('someData').equalTo({fieldB: 'there it was'});

我怎样才能做到这一点 ？谢谢你的帮助.

是的,您可以使用orderByChild和equalTo创建查询ref:

var theRef = firebase.database()
  .ref('someData')
  .orderByChild('fieldB')
  .equalTo('there it was');

theRef.once('value',
  function (snapshot) {
    snapshot.forEach(function (child) {
      console.log(child.key, child.val());
    });
  },
  function (error) {
    console.log(error);
  }
);

theRef.once('value')
  .then(function (snapshot) {
    snapshot.forEach(function (child) {
      console.log(child.key, child.val());
    });
  })
  .catch(function (error) {
    console.log(error);
  });

theRef.on('value',
  function (snapshot) {
    snapshot.forEach(function (child) {
      console.log(child.key, child.val());
    });
  },
  function (error) {
    console.log(error);
  }
);