express-inventory-application/controllers/category.js

const Category = require("../models/category.js");
const Item = require("../models/item.js");
const asyncHandler = require("express-async-handler");
const { body, validationResult } = require("express-validator");

exports.index = asyncHandler(async (req, res, next) => {
  // get array of relevant variables for displaying category and its items
  // get current category from URL
  const category = await Category.findOne({
    simpleName: req.params.category,
  })
    .lean()
    .exec();
  // check
  if (category === null) {
    const error = new Error("Category not found");
    return next(error);
  }
  // get all items from category
  const items = await Item.find({ category: category._id }).lean().exec();
  // render with all relevant vars
  res.render("category", {
    category: category,
    items: items,
  });
});

exports.category_create_get = (req, res, next) => {
  res.render("createcategory");
};

exports.category_create_post = [
  // Validate and sanitize name
  body("name", "Category must have a name!")
    .trim()
    .isLength({ min: 1 })
    .escape(),

  // Validate and sanitize description
  body("description", "Category must have a description!")
    .trim()
    .isLength({ min: 1 })
    .escape(),

  // Process request after validation and sanitization.
  asyncHandler(async (req, res, next) => {
    // Extract the validation errors from a request.
    const errors = validationResult(req);

    // Create a new category with escaped and trimmed data.
    const category = new Category({
      name: req.body.name,
      simpleName: req.body.name.toLowerCase().replace(" ", ""),
      description: req.body.description,
    });

    // if there are validation errors
    if (!errors.isEmpty()) {
      // Render the creation form again with sanitized values/error messages.
      res.render("createcategory", {
        errors: errors.array(),
      });
      return;
    }
    // Data from form is valid.
    else {
      // Check if Category with same name already exists.
      const categoryExists = await Category.findOne({
        name: req.body.name,
      }).exec();
      if (categoryExists) {
        // Category exists, redirect to its page.
        res.redirect(`/${categoryExists.simpleName}`);
      }
      // else category is unique
      else {
        await category.save();
        // saved. Redirect to new category page.
        res.redirect(`/${category.simpleName}`);
      }
    }
  }),
];

exports.category_delete_get = asyncHandler(async (req, res, next) => {
  // get current category from URL
  const category = await Category.findOne({
    simpleName: req.params.category,
  })
    .lean()
    .exec();
  // check
  if (category === null) {
    const error = new Error("Category not found");
    return next(error);
  }
  // else, continue to find all relevant items (if any)
  const items = await Item.find({ category: category._id }).lean().exec();
  // if items found
  if (items.length > 0) {
    // delete all items from db - for loop used for practicality reasons (forEach() doesn't play well with async)
    for (let i = 0; i < items.length; i++) {
      const itemID = items[i]._id;
      await Item.findByIdAndDelete(itemID);
    }
  }
  // delete category
  await Category.findByIdAndDelete(category._id);
  // redirects to Home
  res.redirect("/");
});

exports.category_update_get = asyncHandler(async (req, res, next) => {
  // get current category from URL
  const category = await Category.findOne({
    simpleName: req.params.category,
  })
    .lean()
    .exec();
  res.render("editcategory", { category: category });
});

exports.category_update_post = [
  // Validate and sanitize name
  body("name", "Category must have a name!")
    .trim()
    .isLength({ min: 1 })
    .escape(),

  // Validate and sanitize description
  body("description", "Category must have a description!")
    .trim()
    .isLength({ min: 1 })
    .escape(),

  // Process request after validation and sanitization.
  asyncHandler(async (req, res, next) => {
    // Extract the validation errors from a request.
    const errors = validationResult(req);

    // find existing category in database
    const dbCat = await Category.findOne({ simpleName: req.params.category })
      .lean()
      .exec();

    // Create a new category with escaped and trimmed data.
    const category = new Category({
      name: req.body.name,
      simpleName: req.body.name.toLowerCase().replace(" ", ""),
      description: req.body.description,
      _id: dbCat._id, // copy original category ID to prevent overwrite errors
    });

    // if there are validation errors
    if (!errors.isEmpty()) {
      // Render the creation form again with sanitized values/error messages.
      res.render("editcategory", {
        category: dbCat,
      });
      return;
    }
    // Data from form is valid.
    else {
      await Category.findByIdAndUpdate(dbCat._id, category, {});
      res.redirect(`/${category.simpleName}`);
    }
  }),
];