automiddleware/middleware/pagination.js

'use strict';

module.exports = function (app) {
  app.middleware = Object.assign(app.middleware || {}, {
    limit: (req, res, next) => {
      if (req.method !=='GET') return next();
      req.limit = {};
      if (req.query.$limit || req.query.$limit === 0) {
        req.limit.limit = parseInt(req.query.$limit);
      }
      if (req.query.$offset || req.query.$limit === 0) {
        req.limit.skip = parseInt(req.query.$offset || '0');
      }
      delete req.query.$limit;
      delete req.query.$offset;
      next();
    },
    projection: (req, res, next) => {
      if (req.method !== 'GET') return next();
      if (req.query.$projection) {
        req.projection = JSON.parse(req.query.$projection);
      }
      delete req.query.$projection;
      next();
    },
    orderBy: (req, res, next) => {
      if (req.method !=='GET') return next();
      if (req.query.$sort) {
        req.sort = JSON.parse(req.query.$sort);
      }
      delete req.query.$sort;
      delete req.query.$desc;
      next();
    },
    pageSize: (req, res, next) => {
      if (req.method !=='GET') return next();
      if (req.query.$pagesize) {
        req.pagesize = parseInt(req.query.$pagesize);
      }
      delete req.query.$pagesize;
      next();
    },
    filter: (req, res, next) => {
      if (req.method !=='GET') return next();
      for (let k in req.query) {
        let p = req.query[k];
        if (p.indexOf('/') === 0 && p.lastIndexOf('/') === p.length){
          req.query[k] = eval(`/${req.query[k].replace(/\//g,'')}/`);
        }
      }
      next();
    }
  });
};