Node.JS追加数组并转换为JSON

Question

I have the below that runs a few functions to grab different data and i am trying to create/append to an array to "create" a new array that i can then JSON.stringify and pass to the Jade view, i seem to only be able to get the "k" variable of the two loops it does and outputs as "coin1coin2" with the "" instead of a JSON array with the balance and addresses (multiples) after each coin name.

// list all wallets //
app.get('/wallet', function(req, res){
    var coins = app.get('coins');
    var addresses = "";
    for (var k in coins) {
        addresses += k;
        console.log('Coin: ' + k);
        //console.log(k+' => '+coins[k]);
        connect(coins[k]);
        client.getBalance('44abc0a80102', 6, function(err, balance) {
            if (err) return console.log(err);
            addresses += balance;
            //console.log('Balance: ' + balance);
        });
        client.getAddressesByAccount('44abc0a80102', function(err, address) {
            if (err) return console.log(err);
            addresses["address"] += address;
        });
    }
    console.log(addresses);
    res.render('wallet', {
        title: 'Wallet',
        address: JSON.stringify(addresses)
    });
});

In the Jade view i am just doing p= address to show the full array so i can at least see what i am getting before creating logic in the view to loop through it.

Answer 1

The problem here is that your for loop is synchronous, whereas your client.getBalance and client.getAddressesByAccount calls are (almost definitely) not.

When your for loop finishes, your client.getBalance and client.getAddressesByAccount operations are still in progress, so they haven't had a chance to populate your addresses thing yet. Thus it is empty when it's passed to the templating system.

You probably want to use something like async 's map method to do this instead. It'd look something like this:

// list all wallets
app.get('/wallet', function(req, res){
    // array? object?
    var coins = app.get('coins');

    async.map(coins, function(coinId, cb) {
        // ???
        console.log('Coin: ' + JSON.stringify(coin));

        // not sure what this does!
        connect(coin);

        client.getBalance('44abc0a80102', 6, function(err, balance) {
            if (err) return cb(err);

            client.getAddressesByAccount('44abc0a80102', function(err, address) {
                if (err) return cb(err);

                return cb(null, {
                    address: address,
                    balance: balance,
                });
            });
        });
    }, function(err, addresses) {
        // note that we only act on an error here
        if (err) {
            return console.log(err);
        }

        // [{address: ..., balance: ...}, ...]
        console.log(addresses);

        res.render('wallet', {
            title: 'Wallet',
            address: JSON.stringify(addresses),
        });
    });
});

The addresses value will be an array of {address: ..., balance: ...} objects. I'm not sure what you were expecting it to be, since at one point you treat it like a string, then you treat it like an object.