mado/mado.js

a not really useful, dumb model generator

var React = require('react');
var request = require('superagent');
var Promise = require('bluebird');
var DataInjector = require('./data_injector');
var isServer = (typeof window == 'undefined');
var _ = require('underscore');

var RegisteredModelNames = {};

var Mado = (function (){
  var model_name;
  var api_url;
  var parse = function(body) {
    return body;
  };
  var indexer = function(mado, i) {
    return i;
  };

  var cached_value = null;
  var injector = null;

  var NewMado = function(name, obj) {
    var context = this;

    context.request = request;

    // 參數檢查
    if(typeof name != 'string' ||
       typeof obj != 'object' ||
       typeof obj.url != 'string' ||
       (obj.parse && typeof obj.parse != 'function') ||
       (obj.key && typeof obj.key != 'function')) {
      var message = "bad parameter to initialize Mado!\n" +
        "example:\n\n" +
        "var books = new Mado('books', {\n" +
        "  url: 'http://api.example.com/books',  // must provide protocol!!\n" +
        "  parse: function(body) {               // callback to parse requested data\n" +
        "    return JSON.parse(body);\n" +
        "  }\n" +
        "});";
      // TODO url 改為相對於目前host
      // TODO throw時帶行號，最好還有stack trace
      throw message;

    } else {
      // 再檢查有無同名的mado
      if(RegisteredModelNames[name]) {
        throw "Mado name conflicted";
      }
      RegisteredModelNames[name] = true;
    }

    // extend with EventEmitter
    var EventEmitter = require('events').EventEmitter;
    _.extend(context, EventEmitter.prototype);
    context.off = context.removeListener;

    context.mado = model_name = name;
    api_url = obj.url;
    parse = obj.parse || parse;
    indexer = obj.key || indexer;

    delete obj.parse;
    delete obj.key;
    delete obj.url;

    // extend all other properies
    _.extend(context, obj);

    context.Injector =  React.createClass({
      render: function() {
        return DataInjector({
          'data-model': context,
          'data-modelName': model_name
        });
      }
    });

    if(!isServer && window.__preloadedModelValues[model_name]) {
      cached_value = window.__preloadedModelValues[model_name];
    }

    context.getter = function getter(force_update){
      var deferred = Promise.defer();
      if(!force_update && cached_value && !isServer) {
        // TODO 加cache expiration
        deferred.resolve(cached_value);

      } else {
        context.request.get(api_url)
          .end(function(err, res) {
            if(err) {
              deferred.reject(err);
            } else {
              // TODO 資料檢查之類的
              cached_value = parse(res.body);
              if(_.isArray(cached_value)) {
                cached_value = _(cached_value).map(function(val, i) {
                  val.key = indexer(val, i);
                  return val;
                });
              }
              deferred.resolve(cached_value);
              context.emit('sync');
            }
          });
      }
      return deferred.promise;
    };
  };

  return NewMado;
})();


module.exports = Mado;