Json 如何创建简单的Typescript元数据注释

我有一些字段在发送到服务器端之前需要格式化

因此，我想使用自定义序列化程序序列化我的typescript类的一些字段，这样做比较理想：

export class Person {
    @serializeWith(MyDateSerializer)
    private date: Date;
}

post(url, value) {
    this.http.post(url, JSON.stringfy(value, (key, val) => {
       if (//value has serializeWith annotation) {
           return //serialize with custom serializer
       }
    }));
}

任何接近这一点的都是可以接受的，任何帮助都是欢迎的。

---

谢谢

我下面的解决方案建立在以下基础之上：

先决条件：

在您的

tsconfig.json

中或在命令行上的TypeScript中启用Decorator和Decorator元数据支持：

tsconfig.json

{
    "compilerOptions": {
        "target": "es5", // you have to target es5+
        "experimentalDecorators": true,
        "emitDecoratorMetadata": true
        // ....
    }
    // ...
}

安装

reflect metadata

包

npm安装--保存开发

反映元数据

serializerWith

Decorator（工厂） decorator工厂是接受一个或多个参数并返回TypeScript在生成的JavaScript代码中使用的decorator函数的工厂

我已选择直接将序列化函数传递到我的装饰器工厂，并使用metdata规范的

反射元数据

实现将序列化器函数与属性关联。稍后我将检索它并在运行时使用它

function serializeWith(serializer: (input: any) => string) : (target: any, propertyKey: string) => void {
    return function(target: any, propertyKey: string) {
        // serialization here is the metadata key (something like a category)
        Reflect.defineMetadata("serialization", serializer, target, propertyKey);
    }
}

使用 给定此序列化程序：

function MyDateSerializer(value : any) : string {
    console.log("MyDateSerializer called");
    return "dummy value";
}

然后，我们可以像这样应用装饰器工厂：

import "reflect-metadata"; // has to be imported before any decorator which uses it is applied

class Greeter {
    @serializeWith(MyDateSerializer)
    public greeting : string;

    constructor(message: string) {
        this.greeting = message;
    }
}

var greetingInstance = new Greeter("hi");

var serializerFunc : (input: any) => string = Reflect.getMetadata("serialization", greetingInstance, "greeting");

serializerFunc(greetingInstance.greeting);

我们可以像这样获取和使用序列化程序：

import "reflect-metadata"; // has to be imported before any decorator which uses it is applied

class Greeter {
    @serializeWith(MyDateSerializer)
    public greeting : string;

    constructor(message: string) {
        this.greeting = message;
    }
}

var greetingInstance = new Greeter("hi");

var serializerFunc : (input: any) => string = Reflect.getMetadata("serialization", greetingInstance, "greeting");

serializerFunc(greetingInstance.greeting);

样品 main.ts

import "reflect-metadata";

function serializeWith(serializer: (input: any) => string) : (target: any, propertyKey: string) => void {
    return function(target: any, propertyKey: string) {
        console.log("serializeWith called: adding metadata");
        Reflect.defineMetadata("serialization", serializer, target, propertyKey);
    }
}


function MyDateSerializer(value : any) : string {
    console.log("MyDateSerializer called");
    return "bla";
}

class Greeter {
    @serializeWith(MyDateSerializer)
    public greeting : string;

    constructor(message: string) {
        console.log("Greeter constructor");
        this.greeting = message;
    }
}

var greetingInstance = new Greeter("hi");

var serializerFunc : (input: any) => string = Reflect.getMetadata("serialization", greetingInstance, "greeting");

var serializedValue = serializerFunc(greetingInstance.greeting);
console.log(serializedValue);

c:\code\tmp\lll>node build\main.js
serializeWith called: adding metadata
Greeter constructor
MyDateSerializer called
bla

输出

import "reflect-metadata";

function serializeWith(serializer: (input: any) => string) : (target: any, propertyKey: string) => void {
    return function(target: any, propertyKey: string) {
        console.log("serializeWith called: adding metadata");
        Reflect.defineMetadata("serialization", serializer, target, propertyKey);
    }
}


function MyDateSerializer(value : any) : string {
    console.log("MyDateSerializer called");
    return "bla";
}

class Greeter {
    @serializeWith(MyDateSerializer)
    public greeting : string;

    constructor(message: string) {
        console.log("Greeter constructor");
        this.greeting = message;
    }
}

var greetingInstance = new Greeter("hi");

var serializerFunc : (input: any) => string = Reflect.getMetadata("serialization", greetingInstance, "greeting");

var serializedValue = serializerFunc(greetingInstance.greeting);
console.log(serializedValue);

c:\code\tmp\lll>node build\main.js
serializeWith called: adding metadata
Greeter constructor
MyDateSerializer called
bla