winnow/lib/normalize-query-options/collection.js

Apply sql-like filters to GeoJSON

const _ = require('lodash')
const { detectEsriFieldType } = require('./helpers')

function normalizeCollection (collection, features) {
  if (!collection) return

  const clonedCollection = _.cloneDeep(collection)

  // Ensure metadata property exists
  clonedCollection.metadata = clonedCollection.metadata || {}

  // metadata.fields not set and at least one feature with properties
  if (!clonedCollection.metadata.fields && _.get(features, '[0].properties')) {
    // fields generated by inspection of feature
    const fields = getFieldsFromFeature(features[0])
    clonedCollection.metadata.fields = fields
  }
  return clonedCollection
}

function getFieldsFromFeature (feature) {
  if (!feature) return
  const { properties = {} } = feature

  return Object.keys(properties).map(key => {
    return {
      name: key,
      type: detectEsriFieldType(properties[key])
    }
  })
}

module.exports = normalizeCollection