Answers for "mongoos query"

query mongodb

const Books = require("Books.js")
async getBooks(req, res, next) {
    let query;

    // Copy req.query
    let reqQuery = { ...req.query };

    // Fields to exclude
    const removeFields = ["select", "sort"];

    // Loop over removeFields and delete them from reqQuery
    removeFields.forEach(param => delete reqQuery[param]);

    // Create query string
    let queryStr = JSON.stringify(reqQuery);

    // Create operators ($gt, $gte, etc)
    queryStr = queryStr.replace(
      /b(gt|gte|lt|lte|in)b/g,
      match => `$${match}`
    );

    // Find resource
    query = Books.findQuery(JSON.parse(queryStr));

    // Select Fields
    if (req.query.select) {
      const fields = req.query.select.split(",").join(" ");
      query = query.select(fields);
    }

    // Sort
    if (req.query.sort) {
      const sortBy = req.query.sort.split(",").join(" ");
      query = query.sort(sortBy);
    } else {
      query = query.sort("-createdAt");
    }

  
    // Pagination
    const page = parseInt(req.query.page, 10) || 1;
    const limit = parseInt(req.query.limit, 10) || 10;
    const startIndex = (page - 1) * limit;
    const endIndex = page * limit;
    const total = await Books.countDocuments();
    query = query.skip(startIndex).limit(limit);
  
    // Executing query
    let books = await query;
  
  	
    // Pagination result
    const pagination = {};

    if (endIndex < total) {
      pagination.next = {
        page: page + 1,
        limit,
      };
    }

    if (startIndex > 0) {
      pagination.prev = {
        page: page - 1,
        limit,
      };
    }

    res.status(200).json({
      success: true,
      count: books.length,
      pagination,
      data: books,
    });
  
  
  }

mongoose query with function(req, res, next)

router.post('/travellers',
    passport.authenticate('jwt', { "session": false }), function(req, res, next) {
    var pickup_location = req.body.pickup_location;
    var delivery_location = req.body.delivery_location;
    var date = req.body.date;
    var sender = req.user._id;
    var locals = {
        travellers: [],
        senders: []
    };

    async.series([
        // Load travels first
        function(callback) {
            Travel.find({ "date": date }, function (err, travels) {
                if (err) return callback(err);
                locals.travels = travels;
                callback();
            });
        },
        // Load users (won't be called before task 1's "task callback" has been called)
        function(callback) {
            async.forEach(locals.travels, function (travel, callback) {
                User.findById(travel.traveller, function (err, user) {
                    if (err) return callback(err);
                    data = {
                        "name": user.name,
                        "email": user.email,
                        "phone": user.phone,
                        "image_url": user.image_url,
                        "type": "traveller"
                    };
                    console.log(data);
                    local.travellers.push(data);
                    callback();
                });
            }, function (err) {
                if (err) return callback(err);
                            callback();
            });
        }
    ], function(err) { /* This function gets called after 
          the two tasks have called their "task callbacks" */
        if (err) return next(err);
        //Here locals will be populated with `travellers` and `senders`
        //Just like in the previous example
        console.log(locals);
        console.log(locals.travellers);
        res.json(locals.travellers);
    });
});