code explanation nodejs expressjs mongoose

Question

i feel a bit embarrassed, can you please kindly explain parts of the code?

For example, I have no idea, what is this part? where can I read more about it?

   function parsePostStory(data) {
      return {
        name : data.name
      }
    }

What is req.body? Is it json req body? Why do we declare empty array and why do we return it? Just for the clarity? Is Story.create just a mongoose method?

The rest of the code is here:

    router.post('/stories', function(req, res) {
      var validation = validatePostStory(req.body);
      if(validation.length > 0) {
        return res.badRequestError(validation);
      }
      var story = parsePostStory(req.body);
      Story.create(story, function(err, story) {
        if(err) {
          console.log(err.message);
          return res.internalServerError();
        } res.send(story);
      });
    });

    function validatePostStory(data) {
      var array = [];
      if (!data.name || typeof data.name !== 'String') {
        return array.push('name');
      }
      return array;
    }

    function parsePostStory(data) {
      return {
        name : data.name
      }
    }

Sorry once more for that kind of a question and thanks a ton.

Nilushanan Kulasingham · Accepted Answer · 2016-09-25 21:24:59Z

2

I'm assuming you know how the request-response cycle works with HTTP requests and the client-server interactions with it. If not, Wikipedia Request-Response and Client-Server (Two link limit, otherwise I would have posted them as links)

A request sends a lot of information to the server. If you console.log the request in NodeJS, you will see that it contains a lot of information that isn't entirely relevant to what you need.

You're using Express as your web framework. In this case, req.body is the information that you are sending to the server from the client. Using req.body will make sure that you're not using the extra information passed in to the server from the client. Req.body is your code that you want. (Note: Req.body isn't natively supported by Express v4, you'll have to use something like body-parser) See Express docs for more details

Now, let's break up this code a bit. You essentially have 3 separate functions. Let's take a look at validatePostStory.

function validatePostStory(data) {
      var array = [];
      if (!data.name || typeof data.name !== 'String') {
        return array.push('name');
      }
      return array;
 }

This function is a validation function. It takes one argument - an object and returns an array. Effectively, what this is doing is checking if the name is a string or not - if not, return an array that has a length of 1. The following conditional checks length and returns a 400 if greater than 0

      if(validation.length > 0) {
        return res.badRequestError(validation);
      }

I'm not entirely sure why this needs to be a separate function. Looks like you can probably just do this instead.

if (!req.body.name || typeof req.body.name !== 'String') {
        return  res.badRequestError(validation);
      }

The following function function essentially converts the data so that mongodb/mongoose can store it in the proper format

function parsePostStory(data) {
      return {
        name : data.name
      }
    }

It's the same as saying:

  var story = {name: req.body.name}

I would assume Story.create is a custom mongoose method yes.

answered Sep 25, 2016 at 21:24

Nilushanan Kulasingham

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4 Comments

Brinka Over a year ago

can you please not? My upvotes are not shown, as I don't have enough reputation, though I am very grateful.

Nilushanan Kulasingham Over a year ago

I'm not sure what the "can you please not" means here, but you're welcome.

Brinka Over a year ago

Sorry, wasn't addressed to you, somebody yesterday shamed me for not giving you upvotes and I explained that I am not able.

Nilushanan Kulasingham Over a year ago

No worries. Hopefully this helped you.

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