Form Validation

validate.js

import Immutable from 'immutable';
import {reduce} from 'lodash';

type ErrorMap = Immutable.Map;
type Validator = (value, path, form) => ErrorMap;

function validationRules(rules) {
  return (value, path, form) => {
    return reduce(rules, (result, fn, key) => {
      if (path.contains(key)) {
        return result.merge(fn(value, path, ctx));
      }
      return result;
    }, Immutable.Map());
  });
}

// TODO consider to support rules objects too
function combine(...validators) {
  return (value, path, form) => {
    return reduce(validators, (result, fn) => {
      return result.merge(fn(value, path, form));
    }, Immutable.Map());
  };
}

function makePredicate(predicate, error) {
  return (value, path, form) => {
    if (!predicate(value)) {
      return Immutable.Map({[path]: error});
    }
    return Immutable.Map();
  };
}

function isNotEmpty(error = 'is empty') {
  return makePredicate(val => !val, error);
}

function isUniqueParameter(error = 'not unique') {
  return (value, path, form) => {
    if (path.contains('parameters.')) {
      const i = path.lastIndexOf('.');
      const paramsKey = path.substr(0, i);
      const name = path.substr(i + 1);
      const params = form.getIn(paramsKey);
      if (params.find(t => t.get('name') === name)) {
        return Immutable.Map({[path]: error});
      }
    }
    return Immutable.Map();
  };
}


// example
const validateForm = validationRules({
    name: combine(isNotEmpty(), isUniqueParameter())
});