Create endpoints for retrieving all the articles and single article giving the id

[vishwaefor]

Steps

• Step 1 GET route for retrieving all the articles GET /articles

  router.get('/', (req, res, next) => {
  Articles.find()
  .populate('author')
  .then(results => {
    res.status(200).json({
      results: results.map(r => {
        return {
          id: r.id,
          title: r.title,
          content: r.content,
          image: r.image,
          author:
            (r.author && { id: r.author._id, name: r.author.name }) || null
        };
      })
    });
  })
  .catch(err => next(err));
  });

• Step 2 GET route for retrieving all the articles GET /articles/:id

  router.get('/:id', (req, res, next) => {
  Articles.findById(req.params.id)
  .populate('author', 'comments.author')
  .then(
    r => {
      if (r) {
        res.status(200).json({
          id: r.id,
          title: r.title,
          content: r.content,
          image: r.image,
          author:
            (r.author && { id: r.author._id, name: r.author.name }) || null
        });
      } else {
        const error = new Error('no article found');
        error.status = 404;
        throw error;
      }
    },
    err => {
      const error = new Error('invalid article id');
      error.status = 400;
      throw error;
    }
  )
  .catch(err => next(err));
  });