ddms(基于 Express 的表单管理系统)源码学习

ddms是基于express的一个表单管理系统，今天抽时间看了下它的代码，其实算不上源码学习，只是对它其中一些小的开发技巧做一些记录，希望以后在项目开发中能够实践下。

• 数据层封装
  • 模块只对外暴露model，由业务层完成具体数据操作；
  • 利用mongoose的schema的static属性，扩展常用、基础的操作

var form = new Schema({
  user: {type: ObjectId, ref: 'User'},
  project: {type: ObjectId, ref: 'Project'},
  sid: {type: String, unique: true,'default': shortid.generate },
  title: {
    type: String,
    required: true,
    default: 'New Form'
  },
  desc: String,
  createDateTime: {
    type: Date,
    default: Date.now
  },
  updateDateTime: {
    type: Date,
    default: Date.now
  },
  schemata: Mixed
});

form.static({
  list: function (callback) {
    return this.find()
      .populate('user',{_id: 1,name: 1,email: 1,role: 1})
      .populate('project',{_id: 1,name: 1,desc: 1})
      .sort({_id: -1})
      .exec(callback)
  },
  listByProjectId: function (projectid,callback) {
    return this.find({project: projectid})
      .populate('user',{_id: 1,name: 1,email: 1,role: 1})
      .populate('project',{_id: 1,name: 1,desc: 1})
      .sort({_id: -1})
      .exec(callback);
  }
});

module.exports = mongoose.model('Form', form);

• 充分利用schema type特性
  • 充分利用schema type的例如gettersettervalidate等 参考：http://mongoosejs.com/docs/2.7.x/docs/schematypes.html。可以将原本业务层的很多处理直接交给mongodb.

var userSchema = new Schema({
  email: {
    type: String,
    required: true, //需要校验
　　//给字段存储前线全部小写处理
    set: function (value) {
      return value.trim().toLowerCase()
    },
　　//校验的方法
    validate: [
      function (email) {
        return (email.match(/[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/i) != null)
      },
      'Invalid email'
    ]
  },
 //。。。。
  twitter: Mixed
});

• 利用ref来实现join，可以存在多个，如下：

var form = new Schema({
  user: {type: ObjectId, ref: 'User'},
  project: {type: ObjectId, ref: 'Project'},
  sid: {type: String, unique: true,'default': shortid.generate },

form.static({
  list: function (callback) {
    return this.find()
      .populate('user',{_id: 1,name: 1,email: 1,role: 1})
      .populate('project',{_id: 1,name: 1,desc: 1})
      .sort({_id: -1})
      .exec(callback)
  },
  listByProjectId: function (projectid,callback) {
    return this.find({project: projectid})
      .populate('user',{_id: 1,name: 1,email: 1,role: 1})
      .populate('project',{_id: 1,name: 1,desc: 1})
      .sort({_id: -1})
      .exec(callback);
  }
});

• 充分利用app.use
  • app.use在express中类似servlet里的filter，属于一种过滤器，它会在每个http请求中被调用
  • ddms通过app.use向req对象中添加model

//app.js中
app.use(function (req, res, next) {
  if (!models.User) return next(new Error("No models."));
  req.models = models;
  return next();
});

//route.js中
exports.showListByProjectId = function (req, res, next) {
  var pid = req.params.projectid;
  var pp = Promise.resolve( req.models.Project.findOne({_id: pid}) );
  var fp = Promise.resolve( req.models.Form.listByProjectId(pid) );

  Promise.all([pp,fp])
    .then(function(docs){
      res.render('forms/list', {project: docs[0],forms: docs[1]});
    }).catch(function (error) {
      return next(error);
    });
};

• 采用bluebird的promise库做同步

之前一直用async，看了下promise，感觉非常清爽，同上例代码

• 利用app.get的多callback实现中间件的效果，如下：

app.get('/formdatas/:formid', authorize.editor, routes.formData.showList);
app.get('/formdatas/create/:formid', authorize.editor, routes.formData.showCreateData);
app.post('/formdatas/create/:formid', writeLog, authorize.editor, routes.formData.createData);
app.get('/formdatas/update/:id', authorize.editor, routes.formData.showUpdateData);
app.post('/formdatas/update/:id', writeLog, authorize.editor, routes.formData.updateData);
app.get('/formdatas/delete/:id', writeLog, authorize.editor, routes.formData.deleteData);
app.get('/formdatas/csv/:formid', writeLog, authorize.editor, routes.formData.getCSV);