node.js - Routing function Express.js and retriving data from json

Question

I have a problem with a routing function in express.

I call from firebase realtime database , the JSON has a lot of nested data and I would like to retrieve it with a for loop.

router.get('/admin_tavoli',  async (req, res) => {
    try {
        var lista_tavoli = await firebase().ref('tavoli').once('value');
        var lista_tavoli_val = lista_tavoli.val();
        for(var i in lista_tavoli_val){
            console.log(lista_tavoli_val[i].comanda.tavolo);
        }
        res.send('ok');
        } catch (err) {
         res.json({ message: err })
        }
   });

If I keep to the first level to JSON for example

for(var i in lista_tavoli_val){
      console.log(lista_tavoli_val[i].comanda);
     }

there are no problems. But if I go deeper to JSON

for(var i in lista_tavoli_val){
      console.log(lista_tavoli_val[i].comanda.tavolo);
     }

the execution of the program goes in error, but the strange thing is that in the terminal I see the correct data. Why does this happen? thanks to all for the help

Answer 1

等待大神答复