validator.js

var Transform = require('readable-stream').Transform;
var inherits = require('inherits');

inherits(Validator, Transform);
module.exports = validator;
function validator(warning, schema) {
  return new Validator(warning, schema);
}
function Validator(warning, schema) {
  Transform.call(this, {
    objectMode: true
  });
  this.warning = warning;
  this.extraKeys = new Set();
  this.schema = schema;
  this.nope = Symbol('nope');
}
Validator.prototype.keyWarning = function (key) {
  if (this.extraKeys.has(key)) {
    return;
  }
  this.extraKeys.add(key);
  this.warning(`An unexpected field "${key}" was encountered. This field was not uploaded`);
};
Validator.prototype._transform = function (chunk, _, next) {
  var self = this;
  var props = chunk.properties;
  chunk.properties = {};
  const schema = this.schema;
  Object.keys(props).forEach(function (key) {
    if (!schema.has(key)) {
      self.keyWarning(key);
      return;
    }
    var typed = self.coerceType(props[key], schema.get(key));
    if (typed === self.nope) {
      return;
    }
    chunk.properties[key] = typed;
  });
  if (chunk.geometry || Object.keys(chunk.properties).length) {
    self.push(chunk);
  }
  next();

};
const falses = new Set(['f','false','n','no','off','0']);
const trues = new Set(['t','true','y','yes','on','1']);
Validator.prototype.coerceType = function (value, type) {
  if (typeof value === 'undefined' || value === null) {
    return this.nope;
  }
  var out;
  switch(type) {
  case 'character':
  case 'text':
    out = String(value);
    if (!out) {
      return this.nope;
    }
    return out;
  case 'double precision':
    out = parseFloat(value);
    if (out !== out) {
      return this.nope;
    }
    return out;
  case 'integer':
    out = parseInt(value, 10);
    if (out !== out) {
      return this.nope;
    }
    if (out > 2147483647 || out < -2147483648 ) {
      return this.nope;
    }
    return out;
  case 'bigint':
    out = parseInt(value, 10);
    if (out !== out) {
      return this.nope;
    }
    return out;
  case 'timestamp with time zone':
  case 'date':
    out = new Date(value);
    if (out.toString() === 'Invalid Date') {
      return this.nope;
    }
    return out;
  case 'boolean':
    if (value === 'NULL') {
      return this.nope;
    }
    if (typeof value !== 'string') {
      return Boolean(value);
    }
    if (falses.has(value.trim().toLowerCase())) {
      return false;
    }
    if (trues.has(value.trim().toLowerCase())) {
      return true;
    }
    return this.nope;
  default:
    return this.nope;
  }
};