使函数成为路由中的快速中间件

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Making a function an express middleware in a route

所以我有一条路线，并且路线中有一些丑陋的代码，我想制作一个中间件。唯一的问题是 Express 的文档不清楚，我的代码只有 404s。

我怎样才能做到这一点？

路线：

router.get('/product/:slug', function(req, res) {

//route params

 var slug = req.params.slug;

 var productResp; //scope up api response to pass to render()

 console.log(slug);

//api call

 Prismic.api("https://prismic.io/api").then(function(api) {

  return api.getByUID('product' , slug);

 }).then(function(response) {



 app.use(markedHtml)

 })

 .catch(function(error) {

  res.render('404');

 })

});
 var markedHtml = function(req, res, next) {

   var md_col_1 = response.data["product.markdown-col-one"].value[0].text;

   var md_col_1_1 = response.data["product.markdown-col-one"].value[1].text;

   var md_col_2 = response.data["product.markdown-col-two"].value[0].text;

   var md_col_2_1 = response.data["product.markdown-col-two"].value[1].text;

   var md_col_3 = response.data["product.markdown-col-three"].value[0].text;

   var md_col_3_1 = response.data["product.markdown-col-three"].value[1].text;





   var html_col_1 = marked(md_col_1);

   var html_col_1_1 = marked(md_col_1_1);

   var html_col_2 = marked(md_col_2);

   var html_col_2_1 = marked(md_col_2_1);

   var html_col_3 = marked(md_col_3);

   var html_col_3_1 = marked(md_col_3_1);







  res.render('product-template', {

   product: response,

   md_one: html_col_1,

   md_one_1: html_col_1_1,

   md_two: html_col_2,

   md_two_1: html_col_2_1,

   md_three: html_col_3,

   md_three_1: html_col_3_1,

  })



   next();

  }

const markedHtml = require('./middleware/markedHtml');

app.use('/product/:slug', markedHtml);

const markedHtml = function(req, res, next) {

 // Do stuff with req.apiResponse here.

 ...



 res.render('product-template', {

  ...

 });

}



module.exports = markedHtml;
router.get('/product/:slug', function(req, res, next) {

 //route params

 var slug = req.params.slug;

 var productResp; //scope up api response to pass to render()

 console.log(slug);



 //api call

 Prismic.api("https://prismic.io/api").then(function(api) {

  return api.getByUID('product' , slug);

 }).then(function(response) {

  req.apiResponse = response;

  next();

 })

 .catch(function(error) {

  res.render('404');

 });

});

功能：

router.get('/product/:slug', function(req, res) {

//route params

 var slug = req.params.slug;

 var productResp; //scope up api response to pass to render()

 console.log(slug);

//api call

 Prismic.api("https://prismic.io/api").then(function(api) {

  return api.getByUID('product' , slug);

 }).then(function(response) {



 app.use(markedHtml)

 })

 .catch(function(error) {

  res.render('404');

 })

});
 var markedHtml = function(req, res, next) {

   var md_col_1 = response.data["product.markdown-col-one"].value[0].text;

   var md_col_1_1 = response.data["product.markdown-col-one"].value[1].text;

   var md_col_2 = response.data["product.markdown-col-two"].value[0].text;

   var md_col_2_1 = response.data["product.markdown-col-two"].value[1].text;

   var md_col_3 = response.data["product.markdown-col-three"].value[0].text;

   var md_col_3_1 = response.data["product.markdown-col-three"].value[1].text;





   var html_col_1 = marked(md_col_1);

   var html_col_1_1 = marked(md_col_1_1);

   var html_col_2 = marked(md_col_2);

   var html_col_2_1 = marked(md_col_2_1);

   var html_col_3 = marked(md_col_3);

   var html_col_3_1 = marked(md_col_3_1);







  res.render('product-template', {

   product: response,

   md_one: html_col_1,

   md_one_1: html_col_1_1,

   md_two: html_col_2,

   md_two_1: html_col_2_1,

   md_three: html_col_3,

   md_three_1: html_col_3_1,

  })



   next();

  }

const markedHtml = require('./middleware/markedHtml');

app.use('/product/:slug', markedHtml);

const markedHtml = function(req, res, next) {

 // Do stuff with req.apiResponse here.

 ...



 res.render('product-template', {

  ...

 });

}



module.exports = markedHtml;
router.get('/product/:slug', function(req, res, next) {

 //route params

 var slug = req.params.slug;

 var productResp; //scope up api response to pass to render()

 console.log(slug);



 //api call

 Prismic.api("https://prismic.io/api").then(function(api) {

  return api.getByUID('product' , slug);

 }).then(function(response) {

  req.apiResponse = response;

  next();

 })

 .catch(function(error) {

  res.render('404');

 });

});

在您的根目录 app.js 中，您应该会看到您的应用正在使用的所有中间件。这些中间件是按顺序匹配的。如果它们不包含路由参数，它们自然会应用于所有请求。您的路线就在其中，它们看起来像这样：app.use('/', routes);.

在 app.js 中的路线下方，声明一个新路线：

router.get('/product/:slug', function(req, res) {

//route params

 var slug = req.params.slug;

 var productResp; //scope up api response to pass to render()

 console.log(slug);

//api call

 Prismic.api("https://prismic.io/api").then(function(api) {

  return api.getByUID('product' , slug);

 }).then(function(response) {



 app.use(markedHtml)

 })

 .catch(function(error) {

  res.render('404');

 })

});
 var markedHtml = function(req, res, next) {

   var md_col_1 = response.data["product.markdown-col-one"].value[0].text;

   var md_col_1_1 = response.data["product.markdown-col-one"].value[1].text;

   var md_col_2 = response.data["product.markdown-col-two"].value[0].text;

   var md_col_2_1 = response.data["product.markdown-col-two"].value[1].text;

   var md_col_3 = response.data["product.markdown-col-three"].value[0].text;

   var md_col_3_1 = response.data["product.markdown-col-three"].value[1].text;





   var html_col_1 = marked(md_col_1);

   var html_col_1_1 = marked(md_col_1_1);

   var html_col_2 = marked(md_col_2);

   var html_col_2_1 = marked(md_col_2_1);

   var html_col_3 = marked(md_col_3);

   var html_col_3_1 = marked(md_col_3_1);







  res.render('product-template', {

   product: response,

   md_one: html_col_1,

   md_one_1: html_col_1_1,

   md_two: html_col_2,

   md_two_1: html_col_2_1,

   md_three: html_col_3,

   md_three_1: html_col_3_1,

  })



   next();

  }

const markedHtml = require('./middleware/markedHtml');

app.use('/product/:slug', markedHtml);

const markedHtml = function(req, res, next) {

 // Do stuff with req.apiResponse here.

 ...



 res.render('product-template', {

  ...

 });

}



module.exports = markedHtml;
router.get('/product/:slug', function(req, res, next) {

 //route params

 var slug = req.params.slug;

 var productResp; //scope up api response to pass to render()

 console.log(slug);



 //api call

 Prismic.api("https://prismic.io/api").then(function(api) {

  return api.getByUID('product' , slug);

 }).then(function(response) {

  req.apiResponse = response;

  next();

 })

 .catch(function(error) {

  res.render('404');

 });

});

在 ./middleware/marketHtml.js 中，您的方法将如下所示，没有 next 调用：

router.get('/product/:slug', function(req, res) {

//route params

 var slug = req.params.slug;

 var productResp; //scope up api response to pass to render()

 console.log(slug);

//api call

 Prismic.api("https://prismic.io/api").then(function(api) {

  return api.getByUID('product' , slug);

 }).then(function(response) {



 app.use(markedHtml)

 })

 .catch(function(error) {

  res.render('404');

 })

});
 var markedHtml = function(req, res, next) {

   var md_col_1 = response.data["product.markdown-col-one"].value[0].text;

   var md_col_1_1 = response.data["product.markdown-col-one"].value[1].text;

   var md_col_2 = response.data["product.markdown-col-two"].value[0].text;

   var md_col_2_1 = response.data["product.markdown-col-two"].value[1].text;

   var md_col_3 = response.data["product.markdown-col-three"].value[0].text;

   var md_col_3_1 = response.data["product.markdown-col-three"].value[1].text;





   var html_col_1 = marked(md_col_1);

   var html_col_1_1 = marked(md_col_1_1);

   var html_col_2 = marked(md_col_2);

   var html_col_2_1 = marked(md_col_2_1);

   var html_col_3 = marked(md_col_3);

   var html_col_3_1 = marked(md_col_3_1);







  res.render('product-template', {

   product: response,

   md_one: html_col_1,

   md_one_1: html_col_1_1,

   md_two: html_col_2,

   md_two_1: html_col_2_1,

   md_three: html_col_3,

   md_three_1: html_col_3_1,

  })



   next();

  }

const markedHtml = require('./middleware/markedHtml');

app.use('/product/:slug', markedHtml);

const markedHtml = function(req, res, next) {

 // Do stuff with req.apiResponse here.

 ...



 res.render('product-template', {

  ...

 });

}



module.exports = markedHtml;
router.get('/product/:slug', function(req, res, next) {

 //route params

 var slug = req.params.slug;

 var productResp; //scope up api response to pass to render()

 console.log(slug);



 //api call

 Prismic.api("https://prismic.io/api").then(function(api) {

  return api.getByUID('product' , slug);

 }).then(function(response) {

  req.apiResponse = response;

  next();

 })

 .catch(function(error) {

  res.render('404');

 });

});

您的原始路线将如下所示：

router.get('/product/:slug', function(req, res) {

//route params

 var slug = req.params.slug;

 var productResp; //scope up api response to pass to render()

 console.log(slug);

//api call

 Prismic.api("https://prismic.io/api").then(function(api) {

  return api.getByUID('product' , slug);

 }).then(function(response) {



 app.use(markedHtml)

 })

 .catch(function(error) {

  res.render('404');

 })

});
 var markedHtml = function(req, res, next) {

   var md_col_1 = response.data["product.markdown-col-one"].value[0].text;

   var md_col_1_1 = response.data["product.markdown-col-one"].value[1].text;

   var md_col_2 = response.data["product.markdown-col-two"].value[0].text;

   var md_col_2_1 = response.data["product.markdown-col-two"].value[1].text;

   var md_col_3 = response.data["product.markdown-col-three"].value[0].text;

   var md_col_3_1 = response.data["product.markdown-col-three"].value[1].text;





   var html_col_1 = marked(md_col_1);

   var html_col_1_1 = marked(md_col_1_1);

   var html_col_2 = marked(md_col_2);

   var html_col_2_1 = marked(md_col_2_1);

   var html_col_3 = marked(md_col_3);

   var html_col_3_1 = marked(md_col_3_1);







  res.render('product-template', {

   product: response,

   md_one: html_col_1,

   md_one_1: html_col_1_1,

   md_two: html_col_2,

   md_two_1: html_col_2_1,

   md_three: html_col_3,

   md_three_1: html_col_3_1,

  })



   next();

  }

const markedHtml = require('./middleware/markedHtml');

app.use('/product/:slug', markedHtml);

const markedHtml = function(req, res, next) {

 // Do stuff with req.apiResponse here.

 ...



 res.render('product-template', {

  ...

 });

}



module.exports = markedHtml;
router.get('/product/:slug', function(req, res, next) {

 //route params

 var slug = req.params.slug;

 var productResp; //scope up api response to pass to render()

 console.log(slug);



 //api call

 Prismic.api("https://prismic.io/api").then(function(api) {

  return api.getByUID('product' , slug);

 }).then(function(response) {

  req.apiResponse = response;

  next();

 })

 .catch(function(error) {

  res.render('404');

 });

});

基本上，您的原始路由将接收客户端请求，执行 API 调用等，然后(双关语！)运行到 next(); 调用。该提示表示执行下一个适用的中间件，恰好是 markedHtml，将从中调用视图渲染方法。

如果有任何不清楚或需要额外解释，请告诉我。

可以在此处找到其他文档：http://expressjs.com/en/4x/api.html#app.use

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