Node.js/Express Routes Code Repetition Problem-CodePudding

I am coding an e-commerce site with Node.js.

I noticed some code repeating while creating the routes but I couldn't find how to get rid of it.

men route is given below:

router.get(`/parent-category-selection`,(req, res, next) => {

categoryRequest.getAllParentCategories('mens', (error, data) => {
  if(!error){
    res.render('category/parentCategorySelection', {parentCategories:data});
  }else {
    res.render('error', {message:'An error occured.'})
  }
})

})

women route is given below:

router.get(`/parent-category-selection`,(req, res, next) => {

categoryRequest.getAllParentCategories('womens', (error, data) => {
  if(!error){
    res.render('category/parentCategorySelection', {parentCategories:data});
  }else {
    res.render('error', {message:'An error occured.'})
  }
})

})

routes in app.js:

app.use('/', indexRouter);


app.use('/men', menRouter)

app.use('/women',womenRouter)

app.use('/product',productRouter)

I want routes like /women/parent-category-selection and /men/parent-category-selection without code repetition. How can I achieve that as you see above router functions are so similar I should find a way to bind gender information to the router like app.use('/:gender', genderRouter {gender:gender}). Any help ?

CodePudding user response：

One pattern you could use is a higher order function, which is a function that returns a function. In this case, it is used to create an express middleware function. For example:

const parentCategorySelectionHandler = (gender) => (req, res) =>
  categoryRequest.getAllParentCategories(gender, (error, data) => {
    if (!error) {
      res.render("category/parentCategorySelection", {
        parentCategories: data,
      });
    } else {
      res.render("error", { message: "An error occured." });
    }
  });

Which can be used like this:

router.get(`/parent-category-selection`, parentCategorySelectionHandler("men"));

If you wanted to get the gender from the URL, as you suggested, you could change it to the following.

middleware

const parentCategorySelectionHandler = (req, res) =>
  categoryRequest.getAllParentCategories(req.params.gender, (error, data) => {
    if (!error) {
      res.render("category/parentCategorySelection", {
        parentCategories: data,
      });
    } else {
      res.render("error", { message: "An error occured." });
    }
  });

usage

router.get(`/parent-category-selection/:gender`, parentCategorySelectionHandler);

Then you'd need to change how you add the men/women routes in app.js since this one route would cover both of those genders.