parse-query-string.js

function parseQueryString(req, res, next) {
  try {
    req.query.filter = parseQueryStringObject(req.query.filter, {})
    req.query.projection = parseQueryStringObject(req.query.projection, {})
    req.query.sort = parseSortOptions(req.query.sort)
    req.query.pagination = parseQueryStringObject(req.query.pagination, {
      page: 1,
      pageSize: 50
    })
    req.query.keywords = req.query.keywords || ''
    next()
  } catch (e) {
    return res.status(400).json(new Error('Invalid JSON'))
  }
}

function parseQueryStringObject(parameter, defaultValue) {
  if (!parameter) return defaultValue
  var result = JSON.parse(parameter)
  if (typeof result !== 'object')
    throw new Error('Invalid parameter provided ' + result)
  return Object.assign({}, defaultValue, result)
}

function parseSortOptions(parameter) {
  if (!parameter) return undefined
  const rawOptions = JSON.parse(parameter)
  let sort = 'asc'
  if (!Array.isArray(rawOptions)) return undefined
  if (!rawOptions.length) return undefined
  if (typeof rawOptions[1] !== 'undefined') sort = rawOptions[1]
  return [[rawOptions[0], sort]]
}

module.exports = parseQueryString