nodejs api请求函数错误处理崩溃应用

Question

I'm trying to make an api call and pass it into a function that stores it into mongodb. The problem is that the entire site crashes when I try to handle errors instead of redirecting to the error page. All my other functions work, it's just the request function containing the api call that doesn't.

Instead of redirecting, I only get the error messages in the terminal.

Here's my code for it:

index.js

router.post('/',async function(req,res){
  var {title,date,loc,count, save,del,update,csv} = req.body;
  var {username} = req.session;
  console.log(req.body);
  var url = `http://api.openweathermap.org/data/2.5/weather?q=${loc}&appid=${API_KEY}&units=metric`

  if(save){
    //weather api       
    request({ url: url, json: true }, async function (error, response) {
      if(error){
        throw new Error ('type error');
      }
      else{
        console.log('Current weather: '
                + response.body.main.temp
                + ' degrees celsius'
        );
        let w = JSON.stringify(response.body.main.temp);
        console.log(w)
        await db.addItem(username,title, loc, count, w, date);
      }
    });
    res.redirect('/');
  }  

app.js

app.use('/', indexRouter);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  next(createError(404));
});

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

Here is what my terminal looks like when the app crashes: terminal error message

Answer 1

You have not describe what to do if an error occurs in the else statement of the request call. So if an error occurs it will crash.

Since you are using async...await in the callback to insert into the db, you can get the functionality you want by wrapping it in a try...catch block and moving the redirect into the catch:

request({ url: url, json: true }, async function (error, response) {
  if(error){
    throw new Error ('type error');
   } else {
     try {
      console.log('Current weather: '
        + response.body.main.temp
        + ' degrees celsius'
      );
      let w = JSON.stringify(response.body.main.temp);
      console.log(w)
      await db.addItem(username,title, loc, count, w, date);
    } catch (error) {
      console.log(error);
      res.redirect('/');
    }
  }
});

However, the throw new Error('type error') will still cause the app to crash here. If you want to also redirect in this case, then you can add a res.redirect('/') there as well instead of throwing, or wrap the entire request call in a try...catch so that the catch block will also catch that thrown type error:

try {
   request({ url: url, json: true }, async function (error, response) {
      if(error){
        throw new Error ('type error');
      }
      else{
        console.log('Current weather: '
                + response.body.main.temp
                + ' degrees celsius'
        );
        let w = JSON.stringify(response.body.main.temp);
        console.log(w)
        await db.addItem(username,title, loc, count, w, date);
      }
    });
} catch (error) {
  res.redirect('/')
}