winnow/lib/filter-and-transform/prepare-filter-and-transform.js

Apply sql-like filters to GeoJSON

const filterAndTransform = require('./filter-and-transform')

module.exports = function (statement) {
  const query = filterAndTransform.compile(statement)
  return function (params) {
    const normalizedParams = normalizeParams(params)
    return query(normalizedParams)
  }
}

function normalizeParams (inParams) {
  let params
  // If this is just a passed in feature
  if (!inParams.length) params = [[inParams]]
  // If this is an array of features
  if (isGeoJSONFeatures(inParams) || isEsriFeatures(inParams)) params = [inParams]
  return params
}

function isGeoJSONFeatures (candidate) {
  const feature = candidate[0] || {}
  if (feature.type && feature.type.toLowerCase() === 'feature') return true
  else return false
}

function isEsriFeatures (candidate) {
  const feature = candidate[0] || {}
  if (feature.attributes || feature.geometry) return true
  else return false
}