node.js - 在哪里存储我的 Node 计划

Question

我是 Node/Express 的新手，我正在做一个预约系统。我希望我的用户在他们想要的那一天进行预约，我的系统会在那个确切的时间向他们发送通知。我发现“node-schedule”模块非常适合这个任务，但我不知道在哪里实现它。无论如何将所有任务存储在我的 app.js 中，或者每次我达到某个终点时只创建一个 Node 计划任务是否足够，例如:

router.get('/', function(req, res, next) {
 var j = schedule.scheduleJob(date, function(){
   send notification();
});
res.send(200);
}

注意:我不想在我的 sql 表上运行常量 for 循环来检查日期

Answer 1

您需要通过使用 SQLite 之类的方式写入本地文件，将您的应用程序数据保存到某种形式的永久存储中。 ，运行您自己的数据库服务器(如 MongoDB )或使用基于云的存储服务，如 Amazon SimpleDb .

这些选项(以及许多其他选项)中的每一个都有 npm 模块，您可以使用它们来读取/写入/删除持久数据。有关示例，请参阅 MongoDb , SQLite3 , 和 SimpleDb ，所有这些都可以在 npmjs.com 上使用 npm .

更新

根据您在下面的评论:好吧，您确实询问了可以在哪里存储已安排的事件。 ;)

要保留所有计划的事件，使其在可能的服务器故障中幸存下来，您需要创建一个可存储的数据结构来表示它们，并为每个事件创建一个新的表示实例并将其存储到持久存储 (MySQL) .

通常，您会使用以下内容:

{
  when:DateTime        -- timestamp when the event should fire
  what:Action          -- what this event should do
  args:Arguments       -- arguments to pass to Action
  pending:Boolean=true -- if false, this event has already fired
}

当您初始化您的服务器时，您将查询您的持久存储以查找所有 pending===true 的事件，并使用结果初始化 node-schedule 的实例模块。

当您需要在服务器运行时安排一个新事件时，您需要创建一个新的事件表示，将其写入持久存储并使用它创建一个新的 node-schedule 实例。

最后，也是最重要的是为了让客户满意，当计划的事件成功完成时，就在您的事件处理程序(上面提到的 Action)完成之前，它需要将它正在处理的事件的持久版本标记为 pending:false，这样您就不会多次触发任何事件。

例如:

  'use strict';
  
  var scheduler = require('node-schedule');

  /**
   * Storable Representation of a Scheduled Event
   *
   * @param {string|Date} when
   * @param {string} what
   * @param {array.<string>} [args=[]]
   * @param {boolean} [pending=true]
   *
   * @property {Date} PersistentEvent.when       - the datetime this event should fire.
   * @property {string} PersistentEvent.what     - the name of the action to run (must match key of PersistentEvent.Actions)
   * @property {array} PersistentEvent.args      - args to pass to action event handler.
   * @property {boolean} PersistentEvent.pending - if true, this event has not yet fired.
   *
   * @constructor
   *
   * @example
   *
   * var PersistentEvent = require('PersistentEvent'),
   *     mysql = require('mysql'),
   *     conn = mysql.createConnection({ ... });
   *
   * conn.connect();
   *
   * // at some point when initializing your app...
   *
   * // assign your persistent storage connection...
   * PersistentEvent.setStore(conn);
   *
   * // load all pending event from persistent storage...
   * PersistentEvent.loadAll$(function (err) {
   *   if (err) {
   *     throw new Error('failed to load all PersistentEvents: ' + err);
   *   }
   *
   *   // from this point on, all persistent events are loaded and running.
   *
   * });
   */
  var PersistentEvent = function (when, what, args, pending) {
    // initialize
    PersistentEvent.Cache.push(this.init({
      when: when,
      what: what,
      args: args,
      pending: pending
    }));
  };
  
  // ==== PersistentEvent Static Methods ====
  
  /**
   * Pre-defined action event handlers.
   * <p>
   * Where the property key will be used to match the PersistentEvent.what property,
   * and the property value is a event handler function that accepts an optional
   * array of args and a callback (provided by PersistentEvent.prototype.schedule)
   * </p>
   *
   * @property {object}
   * @property {function} Actions.doSomething
   * @property {function} Actions.doSomethingElse
   *
   * @static
   */
  PersistentEvent.Actions = {
    doSomething: function (args, cb) {
      // defaults
      args = args || [];
  
      // TODO check specific args here ...
  
      var result = true,
          err = null;
  
      // do your action here, possibly with passed args
  
      cb(err, result);
    },
    doSomethingElse: function (args, cb) {
      // defaults
      args = args || [];
  
      // TODO check specific args here ...
  
      var result = true,
          err = null;
  
      // do your action here, possibly with passed args
  
      cb(err, result);
    }
  };
  
  /**
   * Cache of all PersistentEvents
   *
   * @type {Array.<PersistentEvent>}
   * @static
   */
  PersistentEvent.Cache = [];
  
  // Data Management
  
  /**
   * Connection to persistent storage.
   * TODO - This should be abstracted to handle other engines that MySQL.
   * @property {object}
   * @static
   */
  PersistentEvent.StorageConnection = null;
  
  /**
   * Sets the storage connection used to persist events.
   *
   * @param {object} storageConnection
   * @static
   */
  PersistentEvent.setStore = function (storageConnection) { // set the persistent storage connection
                                                            // TODO - check args here...
  
    // Note: this function isn't really needed unless you're using other kinds of storage engines
    // where you'd want to test what engine was used and mutate this interface accordingly.
  
    PersistentEvent.StorageConnection = storageConnection;
  };
  
  /**
   * Saves a PersistentEvent to StorageConnection.
   *
   * @param {PersistentEvent} event - event to save
   * @param {function} cb - callback on complete
   * @static
   */
  PersistentEvent.save$ = function (event, cb) {
    var conn = PersistentEvent.StorageConnection;
  
    if (null === conn) {
      throw new Error('requires a StorageConnection');
    }
  
    // TODO - check for active connection here...
  
    // TODO - check args here...
  
    conn.query('INSERT INTO TABLE when = :when, what = :what, args = :args, pending = :pending', event, cb);
  };
  
  /**
   * Loads all PersistentEvents from StorageConnection.
   * @param {function} cb -- callback on complete
   * @static
   */
  PersistentEvent.loadAll$ = function (cb) {
    var conn = PersistentEvent.StorageConnection;
  
    if (null === conn) {
      throw new Error('requires a StorageConnection');
    }
  
    // check for active connection here...
  
    // check args here...
  
    conn.query('QUERY * FROM TABLE WHERE pending = true', function (err, results) {
      if (err) {
        return cb(err);
      }
      results.forEach(function (result) {
        // TODO: check for existence of required fields here...
        var event = new PersistentEvent(result.when, result.what, result.args, true);
        event.schedule();
      });
      cb(null);
    });
  };
  
  // ==== PersistentEvent Methods ====
  
  /**
   * Initialize an instance of PersistentEvent.
   *
   * @param {object} opts
   * @return {PersistentEvent}
   */
  Event.prototype.init = function (opts) {
    // check args
    if ('object' !== typeof opts) {
      throw new Error('opts must be an object');
    }
  
    // set defaults
    opts.args = opts.args || [];
    opts.pending = opts.pending || true;
  
    // convert string to Date, if required
    if ('string' === typeof opts.when) {
      opts.when = new Date(opts.when);
    }
  
    // check that opts contains needed properties
    if (!opts.when instanceof Date) {
      throw new Error('when must be a string representation of a Date or a Date object');
    }
  
    if ('string' !== typeof opts.what) {
      throw new Error('what must be a string containing an action name');
    }
  
    if (!Array.isArray(opts.args)) {
      throw new Error('args must be an array');
    }
  
    if ('boolean' !== typeof opts.pending) {
      throw new Error('pending must be a boolean');
    }
  
    // set our properties
    var self = this;
    Object.keys(opts).forEach(function (key) {
      if (opts.hasOwnProperty(key)) {
        self = opts[key];
      }
    });
  
    return this;
  };
  
  /**
   * Override for Object.toString()
   * @returns {string}
   */
  PersistentEvent.prototype.toString = function () {
    return JSON.stringify(this);
  };
  
  /**
   * Schedule the event to run.<br/>
   * <em>Side-effect: saves event to persistent storage.</em>
   */
  PersistentEvent.prototype.schedule = function () {
    var self = this,
        handler = Actions[this.what];
  
    if ('function' !== typeof handler) {
      throw new Error('no handler found for action:' + this.what);
    }
  
    PersistentEvent.save$(self, function () {
      self._event = scheduler.scheduleJob(self.when, function () {
        handler(self.args, function (err, result) {
          if (err) {
            console.error('event ' + self + ' failed:' + err);
          }
          self.setComplete();
        });
  
      });
    });
  };
  
  /**
   * Sets this event complete.<br/>
   * <em>Side-effect: saves event to persistent storage.</em>
   */
  PersistentEvent.prototype.setComplete = function () {
    var self = this;
    delete this._event;
    this.pending = false;
    PersistentEvent.save$(this, function (err) {
      if (err) {
        console.error('failed to save event ' + self + ' :' + err);
      }
    });
  };

请注意，这是一个首次通过的样板文件，向您展示了一种设计问题解决方案的方法。它将需要您进一步努力才能运行。