old_contents: import mongoose from 'mongoose'
  import {logger, http_logger} from './utils/logger'
  import express from 'express'
  import cookie_parser from 'cookie-parser'
  import body_parser from 'body-parser'
  import express_validator from 'express-validator'
  import {group_router} from './routers/group_router'
  import {user_router} from './routers/user_router'
  import {error_handler} from './utils/errors'
  
  mongoose.Promise = global.Promise
  mongoose
    .connect(
      process.env.VK_GROUP_STATS_MONGODB_HOST || 'localhost',
      process.env.VK_GROUP_STATS_MONGODB_DATABASE || 'vk-group-stats',
      process.env.VK_GROUP_STATS_MONGODB_PORT || 27017
    )
    .then(() => {
      logger.info('app connected to MongoDB')
  
      const app = express()
      app.use(http_logger)
      app.use(cookie_parser())
      app.use(body_parser.json())
      app.use(express_validator())
      app.use(group_router)
      app.use(user_router)
      app.use(error_handler)
  
      const port = process.env.VK_GROUP_STATS_SERVER_PORT || 3000
      app.listen(port, () => {
        logger.info(`app listening on port ${port}`)
      })
    })
    .catch(error => {
      logger.error(`app can't connect to MongoDB: ${util.inspect(error)}`)
    })
  
new_contents: import mongoose from 'mongoose'
  import {logger, http_logger} from './utils/logger'
  import express from 'express'
  import cookie_parser from 'cookie-parser'
  import body_parser from 'body-parser'
  import express_validator from 'express-validator'
  import {group_router} from './routers/group_router'
  import {user_router} from './routers/user_router'
  import {error_handler} from './utils/errors'
  
  mongoose.Promise = global.Promise
  mongoose
    .connect(
      process.env.VK_GROUP_STATS_MONGODB_HOST || 'localhost',
      process.env.VK_GROUP_STATS_MONGODB_DATABASE || 'vk-group-stats',
      process.env.VK_GROUP_STATS_MONGODB_PORT || 27017
    )
    .then(() => {
      logger.info('app connected to MongoDB')
  
      const app = express()
      app.use(http_logger)
      app.use(cookie_parser())
      app.use(body_parser.urlencoded({
        extended: true,
      }))
      app.use(body_parser.json())
      app.use(express_validator())
      app.use(group_router)
      app.use(user_router)
      app.use(error_handler)
  
      const port = process.env.VK_GROUP_STATS_SERVER_PORT || 3000
      app.listen(port, () => {
        logger.info(`app listening on port ${port}`)
      })
    })
    .catch(error => {
      logger.error(`app can't connect to MongoDB: ${util.inspect(error)}`)
    })
  
subject: Extend a request body parsing