如何解决“ TypeError：app.use需要中间件功能”？

如何解决如何解决“ TypeError：app.use需要中间件功能”？

这是我的server.js文件和api.js文件。我在排序函数中出错，我打算根据其属性搜索js对象。事件模式具有名称，位置，价格，等级等属性。我试图根据他们的价格对其进行排序。 “ TypeError：app.use（）需要中间件功能”吗？

索引路由器

router.post('/add_products',function (req,res) {

  var imageFile = typeof req.files.image !== "undefined" ? req.files.image.name : "";

  req.checkBody('productName','product name must have a value.').notEmpty();
  req.checkBody('information','information must have a value.').notEmpty();
  req.checkBody('category','category must have a value.').notEmpty();
  req.checkBody('price','Price must have a value.').isDecimal();
  req.checkBody('image','You must upload an image').isImage(imageFile);

  var userId = req.user._id
  var productName = req.body.productName;
  var slug = title.replace(/\s+/g,'-').toLowerCase();
  var information = req.body.information;
  var price = req.body.price;
  var category = req.body.category;




  const errors = validationResult(req);
  if (!errors.isEmpty()) {

    var messageValidation = []
    for (var i = 0; i < errors.errors.length; i++) {
      messageValidation.push(errors.errors[i].msg)
    }
    console.log(messageValidation);
    req.flash('signupError',messageValidation)
    res.render('add_products',{
              errors:errors,userId : userId,productName: productName,information: information,category: category,price: price
    })
    return;
  }
 else {
      Product.findOne({slug: slug},function (err,product) {
          if (product) {
              req.flash('danger','Product title exists,choose another.');
              Category.find(function (err,categories) {
                  res.render('add_products',{
                      title: title,desc: desc,categories: categories,price: price
                  });
              });
          } else {

              var price2 = parseFloat(price).toFixed(2);

              var product = new Product({
                  title: title,slug: slug,price: price2,image: imageFile
              });

              product.save(function (err) {
                  if (err)
                      return console.log(err);

                  mkdirp('public/product_images/' + product._id,function (err) {
                      return console.log(err);
                  });

                  mkdirp('public/product_images/' + product._id + '/gallery',function (err) {
                      return console.log(err);
                  });

                  mkdirp('public/product_images/' + product._id + '/gallery/thumbs',function (err) {
                      return console.log(err);
                  });

                  if (imageFile != "") {
                      var productimage = req.files.image;
                      var path = 'public/product_images/' + product._id + '/' + imageFile;

                      productimage.mv(path,function (err) {
                          return console.log(err);
                      });
                  }

                  req.flash('success','Product added!');
                  res.redirect('/admin/products');
              });
          }
      });
  }

});

在应用js中

// Express Validator middleware
app.use(expressValidator({
  errorFormatter: function (param,msg,value) {
      var namespace = param.split('.'),root = namespace.shift(),formParam = root;

      while (namespace.length) {
          formParam += '[' + namespace.shift() + ']';
      }
      return {
          param: formParam,msg: msg,value: value
      };
  },customValidators: {
      isImage: function (value,filename) {
          var extension = (path.extname(filename)).toLowerCase();
          switch (extension) {
              case '.jpg':
                  return '.jpg';
              case '.jpeg':
                  return '.jpeg';
              case '.png':
                  return '.png';
              case '':
                  return '.jpg';
              default:
                  return false;
          }
      }
  }
}));

我该怎么做才能解决此问题