node.js - 如何使用静态方法扩展类？

Question

我想使用静态函数扩展我的 UserModel.model 对象。我该怎么做？

正如你在下面看到的，我的UserModel.model是一个 Mongoose 模型对象，但我需要向这个对象添加方法，重点是:我不知道如何编写它。我无法像 Java/C# 中那样使用 static{} 区域来执行静态代码，我找不到编写它的方法。你是吗？

例如，我想添加诸如 exists、connect 等方法。

///<reference path='../../lib/def/defLoader.d.ts'/>

import model = require('./Model');

export module Models {
    export class UserModel extends model.Models.Model implements model.Models.IModel{
        /**
         * Name of the model.
         * MUST start by uppercase letter!
         */
        private static modelName: string = 'User';

        /**
         * Public readable schema as object.
         */
        public static schema: any = {
            /**
             * User Login
             */
            login: {
                type: 'string',
                minLength: 4,
                maxLength: 16,
                required: true,
                notEmpty: true,
                unique: true
            }
        };

        /**
         * Private schema as mongoose.Schema type.
         */
        private static _schema: mongoose.Schema = new mongoose.Schema(UserModel.schema);

        /**
         * The mongoose model that uses the mongoose schema.
         */
        public static model: mongoose.Model<any> = mongoose.model(UserModel.modelName, UserModel._schema);



        /**
         *************************************************************************************************
         *********************************** Public (Helpers) ********************************************
         *************************************************************************************************
         */

        /**
         * Name of the model.
         * MUST start by uppercase letter!
         */
        public modelName: string;

        /**
         * Contains the static value of the public schema as object.
         * It's a helper to always get the schema, from instance or static.
         */
        public schema: mongoose.Schema;

        /**
         * Contains the static value of the object used to manipulate an instance of the model.
         * It's a helper to always get the model, from instance or static.
         */
        public model: mongoose.Model<any>;

        /**
         * Use static values as instance values.
         */
        constructor(){
            super();

            // Use static values as instance values.
            this.modelName = UserModel.modelName;
            this.schema = UserModel.schema;
            this.model = UserModel.model;
        }

        /**
         *************************************************************************************************
         *********************************** Extended methods ********************************************
         *************************************************************************************************
         */
    }
}

Answer 1

我建议您使用标准 MongooseJS 方式，通过使用 Schema 实例的 statics 属性向模型添加静态方法，如下所示。

module MongooseDemo {
    export class Demo {
        public static LoginSchema: any = {
            /* User Login */
            login: {
                type: 'string',
                minLength: 4,
                maxLength: 16,
                required: true,
                notEmpty: true,
                unique: true
            }
        };      

        public static Model : any; // static store for data 

        constructor() {
            // there is not a concept of a static constructor in  
            // typescript, so static initialization code may be better else
            // where
        }       
    }

    // I've made this an anonymous function that is private to the module
    // It's executed immediately and initializes the "static" values of the 
    // class. this code could be moved into a static method of course and 
    // and called directly in the same way
    (()=> {
        // create the schema defined
        var schema : any = mongoose.Schema(Demo.LoginSchema);
        // add the statics before creating the model
        // http://mongoosejs.com/docs/guide.html#statics
        schema.statics.exists = () => {
           // here's a static method                    
        };
        // create the model
        Demo.Model = mongoose.Model('Demo', schema);

    })();
}

由于 JavaScript 或 Typescript 中没有静态构造函数的概念，因此我在 MongooseDemo 模块内创建了一个匿名函数来自动初始化类的静态字段。您当然可以移动代码，但总体概念应该可行。

或者，您可以在创建模型后直接将静态方法添加到模型中(同样是在匿名方法中):

Demo.Model.exists2 = () => {
    // something different              
};

在 Mongoose 中添加类方法/静态的实际代码非常简单，因为它只是将所有函数(和属性)从 Schema 对象实例的 statics 属性直接复制到新的 Model 中。因此，我提供的第二个示例在功能上等同于我提出的第一种方式，即 documented .