Functional validations

func_validations.js

var Validator = require('simple-validate');

var validateTenantArgs = Validator.validateOrThrow({
  title: 'somePred',
  etc: '...'
});

// current style
function postTenantToSystemTenant(systemTenant, tenantArgs) {
  validateTenantArgs(tenantArgs);

  return systemTenant.post(tenantArgs);
}

// proposed
// MjEntity -> Object -> MjEntity
// validateOrThrow throws an error if an argument is invalid
// otherwise it passes the arguments along
var postTenantToSystemTenant = compose(createTenant, validateTenantArgs);

function createTenant(systemTenant, tenantArgs) {
  return systemTenant.post(tenantArgs);
}

// really style needs to be:
// so system tenant gets passed along to create tenant
// and validate tenant args passes the validated arguments along
var postTenantToSystemTenant = useWith(createTenant, R.I, validateTenantArgs);

// or create a utility to handle this
var postTenantToSystemTenant = Utils.makePostHandler(
  validateTenantArgs,
  // conversion function?
  createTenant
);

// Fn -> Fn -> (MjEntity -> Object -> MjEntity)
Utils.makePostHandler = function(validationFn, creationFn) {
  return useWith(creationFn, R.identity, validationFn);
};

// Fn -> Fn -> (MjEntity -> Object -> MjEntity)
Utils.makePostHandler = function(validationFn, creationFn) {

  // MjEntity -> Object -> MjEntity
  return function(targetEntity, entityArgs) {
    validationFn(entityArgs);
  
    return creationFn(targetEntity, entityArgs);
  };
};

spike2.js

Utils.makePostHandler = function(config) {
  var creationFn     = config.creation,
      validateTarget = config.validateTarget || R.I,
      validateArgs   = config.validateArgs   || R.I,
      conversionFn   = config.conversion     || R.I,

      validateAndConvertArgs = R.compose(conversionFn, validateArgs);

  if(!creationFn) {
    throw new Error('Cannot make post handler without a creation function');
  }

  return R.useWith(creationFn, validateTarget, validateAndConvertArgs);
};

var validateTarget = Validator.validateOrThrow({
  dsKey: R.eq('system')
});

var validateTenantArgs = Validator.validateOrThrow({
  title: Validator.required(R.is(String)),
  description: R.is(String)
});

// var convertArgs = function(args) {
//   if(args.img.data) {
//     return convertImgData(args);
//   }
// };

function createTenant(systemTenant, tenantArgs) {
  return systemTenant.post(tenantArgs);
}

module.exports = Utils.makePostHandler({
  validateTarget: validateTarget,
  validateArgs: validateTenantArgs,
  creationFn: createTenant
});