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Question

我是javascript的新手，我正在努力进行同步/异步函数调用，尤其是在这里，因为我试图连接同一数据库的两个集合中的数据。

这是我的代码：

class BraintreePaymentProcessFormView(FormView):
    template_name = 'startupconfort/cart.html'
    success_url = '/'
    form_class = BraintreeSaleForm
    http_method_names  = ['post']
    success_url = reverse_lazy('my_shopping_cart')

    def get_context_data(self, **kwargs):
        # import ipdb; ipdb.set_trace()
        context = super().get_context_data(**kwargs)
        context['client_token'] = get_braintree_client_token()
        return context

    def form_valid(self, form):
        # import ipdb; ipdb.set_trace()
        user = self.request.user
        nonce = form.cleaned_data['payment_method_nonce']

        result = braintree.Transaction.sale({
            "amount": get_total_price_of_the_shipping_cart(user),
            "payment_method_nonce": nonce,
            "options": {
                "submit_for_settlement": True
            }
        })
        reverse_lazy('my_shopping_cart')
        # import ipdb; ipdb.set_trace()
        if result.is_success or result.transaction:
            print(result.transaction)
            messages.success(self.request, 'Payment proceed successfully')
            # Add Total into db with User Name and Product  + Quantity

            #send email
            user = self.request.user
            billing_email = user.shipping_address.billing_email
            customer_name = user.shipping_address.customer_name
            #total values
            #msg

            # Email with mailjet..
            msg = EmailMultiAlternatives(
                subject="Please activate your account",
                body="Click to activate your account: http://localhost:8000/",
                from_email="Example <admin@example.com>",
                to=[
                    "New User <user1@example.com>"
                    ],
                reply_to=["Helpdesk <support@example.com>"]
            )

            # Send it:
            # msg.send()

            #Clear Cart
            CartItem.objects.filter(customer=user).all().delete()
            # return super().form_valid(form)
            import ipdb; ipdb.set_trace()      
        return HttpResponseRedirect(self.get_success_url()) 

        def form_invalid(self,form):
        # Add action to invalid form phase
            messages.success(self.request, 'An error occured while processing the payment')
            return self.render_to_response(self.get_context_data(form=form))

并返回function getAcquisitionAreas(req) { PartAreas.getAcquisitionAreasByAcquisitionId(req.params.id, (err, partArea) => { particle.areas = partArea._doc.areas; }); } function getAcquisitionPerimeters(req) { PartPerimeters.getAcquisitionPerimetersByAcuiqisiontId(req.params.id, (err, partPerimeter) => { particle.borders_intern = partPerimeter._doc.borders_intern; particle.borders_extern = partPerimeter._doc.borders_extern; }); } function getParticleData(req, callback) { getAcquisitionAreas(req); getAcquisitionPerimeters(req); callback; } function constructParticle(req) { particle.id = req.params.id; } // Register router.get('/get/:id', (req, res, next) => { getParticleData(req); constructParticle(req); res.send(particle); });，这意味着它在放入区域和边框之前执行{"id":"1508515120"}。我该如何实现呢？我已经看过Promises但是无法使它工作，并且在回调方法中实现回调方法似乎很脏。

谢谢！

修改

res.send(particle)

编辑2

我终于设法找到了一个有效的解决方案：

var particle;

function getAcquisitionAreas(req) {
    return new Promise((resolve, reject) => {
    PartAreas.getAcquisitionAreasByAcquisitionId(req.params.id, (err, partArea) => {
            if (err) { reject(err); }

        particle.areas = partArea._doc.areas;
        resolve();
    });
});
}

function getAcquisitionPerimeters(req) {
    return new Promise((resolve, reject) => {
    PartPerimeters.getAcquisitionPerimetersByAcuiqisiontId(req.params.id, (err, partPerimeter) => {
        if (err) { reject(err); }

        particle.borders_intern = partPerimeter._doc.borders_intern;
        particle.borders_extern = partPerimeter._doc.borders_extern;
        resolve();

    });
   })
}

function constructParticle(req) {
    return new Promise((resolve, reject) => {
    particle.id = req.params.id;
        resolve();
    })
}

function sendParticle(res) {
    res.send(particle);
}

// Register
router.get('/get/:id', (req, res, next) => {
    particle = {};
    getAcquisitionAreas(req)
        .then(getAcquisitionPerimeters(req))
        .then(constructParticle(req))
        .then(sendParticle(res));
});

Answer 1

有几种方法可以实现这一目标（Promises，Yield，Async / Await）。你已经尝试过Promises，所以让我们来看看。我已经在这里做了一些假设，并且有更简洁的方法可以做到这一点，但考虑到你发布的代码示例，下面的代码示例应该会给你带来最多，如果不是所有我认为的那样。

function getAcquisitionAreas(req) {
    return new Promise((resolve, reject) => {
    PartAreas.getAcquisitionAreasByAcquisitionId(req.params.id, (err, partArea) => {
            if (err) { return reject(err); }

        particle.areas = partArea._doc.areas;
        resolve();
    });
});
}

function getAcquisitionPerimeters(req) {
    return new Promise((resolve, reject) => {
    PartPerimeters.getAcquisitionPerimetersByAcuiqisiontId(req.params.id, (err, partPerimeter) => {
            if (err) { return reject(err); }
        particle.borders_intern = partPerimeter._doc.borders_intern;
        particle.borders_extern = partPerimeter._doc.borders_extern;
        resolve();
        });
   })
}

function getParticleData(req, callback) {
    getAcquisitionAreas(req)
        .then(getAcquisitionPerimeters(req));
        .then(callback);
}

function constructParticle(req) {
    particle.id = req.params.id;
}

// Register
router.get('/get/:id', (req, res, next) => {
    getParticleData(req, () => {
        constructParticle(req);
            res.send(particle);
    });
});

我做的事情就像捕捉承诺被拒绝时抛出的错误一样，对我来说，从承诺切换到中间的回调似乎很奇怪，但希望上面的例子能给你一个基本的想法如何使用它们。

同步数据库检索javascript

修改

编辑2

1 个答案: