Question

im试图使用node.js设置API，并在我的app.js类中处理请求错误，以防万一出问题我返回404，这就是我的问题，我看不到我如何请求任何东西错误，我仍然收到404错误，即时通讯正试图像这样向我的API发送发布请求：

{
    "name":"Harry Potter 5",
    "price":"12.99"
}

那我明白了

这是我的app.js

const express = require('express');
const app = express();
const morgan = require('morgan');
const productRoutes = require('./api/routes/product');
const orderRoutes = require('./api/routes/order');
const bodyParser = require('body-parser');

app.use(morgan('dev'));
app.use(bodyParser.urlencoded({
    extended:false
}));
app.use(bodyParser.json());
app.use((req, res, next) => {
    const error = new Error("Not found");
    error.status = 404;
    next(error);
  });

  app.use((error, req, res, next) => {
    res.status(error.status || 500);
    res.json({
      error: {
        message: error.message
      }
    });
  });
app.use('/products', productRoutes);
app.use('/orders', orderRoutes);

module.exports = app;

这是我的product.js

const express = require('express');
const router = express.Router();

router.get('/', (req, res, next) => {
    res.status(200).json({
        message: 'Handling GET requests to /products'
    });
});

router.post('/', (req, res, next) => {
    const product = {
        name: req.body.name,
        price: req.body.price
    };
    res.status(201).json({
        message: 'Handling POST requests to /products',
        createdProduct: product
    });
});

router.get('/:productId', (req, res, next) => {
    const id = req.params.productId;
    if (id === 'special') {
        res.status(200).json({
            message: 'You discovered the special ID',
            id: id
        });
    } else {
        res.status(200).json({
            message: 'You passed an ID'
        });
    }
});

router.patch('/:productId', (req, res, next) => {
    res.status(200).json({
        message: 'Updated product!'
    });
});

router.delete('/:productId', (req, res, next) => {
    res.status(200).json({
        message: 'Deleted product!'
    });
});

module.exports = router;

Answer 1

这是因为您正在将所有错误设置为：）

请参阅here中的文档-通过提供的链接：

编写错误处理程序在中定义错误处理中间件功能除错误处理外，与其他中间件功能相同函数具有四个参数，而不是三个：（err，req，res，next）。例如：
// pay attention to err param
app.use(function (err, req, res, next) {
   console.error(err.stack)`  
   res.status(500).send('Something broke!')
})

在您的代码中，您具有以下功能：

app.use((req, res, next) => {
    const error = new Error("Not found");
    error.status = 404;
    next(error);
  });

告诉我们，每个请求都应以404响应。您应该将其设置为适当的错误处理程序，或将其删除。

Answer 2

这是因为任何请求都会执行404处理程序。

看一下这段简短的代码：

for kk in range(1,10):
    # ---- set initial conditions (random)
    decisionE.gen = decisionE.gen * (1 + 0.2 * rand(decisionE.__len__()))
    decisionI.gen = decisionI.gen * (1 + 0.2 * rand(decisionI.__len__()))
    decisionE.V = decisionE.V + rand(decisionE.__len__()) * 2 * mV
    decisionI.V = decisionI.V + rand(decisionI.__len__()) * 2 * mV

    # ---- set initial conditions (random)
    sensoryE.V = -50.0 * mV - 2 * mV + rand(sensoryE.__len__()) * 2 * mV
    sensoryI.V = -50.0 * mV - 2 * mV + rand(sensoryI.__len__()) * 2 * mV
    sensoryE.gea = 0.05 * (1 + rand(sensoryE.__len__()) * 0.2)
    sensoryI.gea = 0.05 * (1 + rand(sensoryI.__len__()) * 0.2)

    # record spikes of excitatory neurons
    S_DE1 = SpikeMonitor(decisionE1, record=True)
    S_DE2 = SpikeMonitor(decisionE2, record=True)
    S_SE1 = SpikeMonitor(sensoryE1, record=True)
    S_SE2 = SpikeMonitor(sensoryE2, record=True)

    # record instantaneous populations activity
    R_DE1 = PopulationRateMonitor(decisionE1, bin=20 * ms)
    R_DE2 = PopulationRateMonitor(decisionE2, bin=20 * ms)
    R_SE1 = PopulationRateMonitor(sensoryE1, bin=20 * ms)
    R_SE2 = PopulationRateMonitor(sensoryE2, bin=20 * ms)

    print kk 

    # ------------------------------------------------------------------------------
    # Run the simulation
    # ------------------------------------------------------------------------------

    # construct network
    net = Network(Dgroups.values(), Sgroups.values(), Dconnections.values(), Sconnections.values(),
                  Dnetfunctions, update_input, C_SE1_DE1, C_SE2_DE2, C_DE1_SE1, C_DE2_SE2,
                  S_DE1, S_DE2, S_SE1, S_SE2, R_DE1, R_DE2, R_SE1, R_SE2)
    net.prepare()
    net.run(runtime)

    ck_=int(runtime/20)-1

    for ii in range(1,ck_):
       if (R_DE1.rate[ii]>=15):
          break

    for jj in range(1,ck_):
       if (R_DE2.rate[jj]>=15):
          break


    if (jj>=ii):
      print R_DE1.rate[ii]
      print ("A fired at ")
      print R_DE1.times[ii]
    else:
      print R_DE2.rate[jj]
      print("B fired at ")
      print R_DE2.times[jj]

在每个请求时打印“进入404处理程序”。现在，如果您以这种方式注释掉404回调：所有请求都会通过500和200回调：

const express = require('express');
const app = express();
const bodyParser = require('body-parser');

app.use(bodyParser.urlencoded({
    extended:false
}));
app.use(bodyParser.json());

app.use((req, res, next) => {
  console.log("Got into 404 handler");

  const error = new Error("Not found");
  error.status = 404;
  next(error);
});

app.use((error, req, res, next) => {
  console.log("Got into 500 handler");

  res.status(error.status || 500);
  res.json({
    error: {
      message: error.message
    }
  });
});
app.use('/products', (req, res, next) => {
  console.log("Got into 200 handler");

  res.status(200).end();
});

app.listen(8080);

现在在您的特定问题中，下面的代码将起作用（我只是交换了处理程序的顺序）：

const express = require('express');
const app = express();
const bodyParser = require('body-parser');

app.use(bodyParser.urlencoded({
    extended:false
}));
app.use(bodyParser.json());

/* there used to be the 404 callback here */

app.use((error, req, res, next) => {
  console.log("Got into 500 handler");

  res.status(error.status || 500);
  res.json({
    error: {
      message: error.message
    }
  });
});
app.use('/products', (req, res, next) => {
  console.log("Got into 200 handler");

  res.status(200).end();
});

app.listen(8080);

希望这会有所帮助。

尝试发送POST请求时收到404错误

2 个答案: