Question

我一直试图通过新的firebase云功能来总结价格来提高总量

"Cart" : {
    "-Ksdasd50oR04q073k5" : {
      "ID" : 0.01,
      "price" : 20
    },
    "-KhOc0CGdsddihGB2N" : {
      "ID" : 001,,
      "price" : 20
    },

这是我的开始，

exports.cartadd = functions.database.ref('Cart/{uid}').onWrite(event => {

   let ref = admin.database().ref('Cart/{uid}');
   return ref.once('value').then(snapshot => {
      if (snapshot.hasChildren()) {
        var total= 0;
        snapshot.forEach(function(child) {

           total += snapshot.val().price;
        });
       console.log(total);
      }
  });

Answer 1

这应该这样做：

exports.cartadd = functions.database.ref('Cart').onWrite(event => {
      const snapshot = event.data;
      if (snapshot.hasChildren()) {
        var total= 0;
        snapshot.forEach(function(item) {
           total += item.child('price').val();
        });
        console.log(total);
      }
  });

Answer 2

试试这个：

old_set = {'NYC', 'Ames', 'LA', 'Houston', '500',  '1000', '3000', 
                  'SanFrancisco', '300', '200', 'Detroit', 'Austin'}

new_set = {elem for elem in old_set if not elem.isdigit()}
print(new_set)
# output:
# {'NYC', 'Ames', 'LA', 'Houston', 'SanFrancisco', 'Detroit', 'Austin'}

Answer 3

由于总需要更改，因此应该是var而不是const。

更改

const total = 0;

到

var total = 0;

Answer 4

total += child.val().price; // instead

Firebase云功能汇总或汇总值

4 个答案: