I have an interface with 200 properties. How can a class implement this interface without declaring-CodePudding

I have an interface with 200 properties and a class that uses these same properties.

interface MyProperties {
  property1: string
  property2: string
  ...
  property232: string
}

class MyClass {
  constructor() {
    this.property1 = 'foo';
    this.property2 = 'bar';
    ...
    this.property232 = 'bar';
  }
}

Right now typescript will give me this error: Property 'property1' does not exist on type 'MyClass'.

Is there a way to tell typescript that my class properties come from the MyProperties interface?

I dont want to do something like this:

class MyClass {
  property1: string
  property2: string
  
  constructor() {
    this.property1 = 'foo';
    this.property2 = 'bar';
  }
}

since the interface is already used extensively in my code and I don't want to repeat these typings.

Closest I've come is this

class MyClass {
  property1: MyProperties['property1'];
  property2: MyProperties['property2'];
  ...
  property232: MyProperties['property232'];

  constructor() {
    this.property1 = 'foo';
    this.property2 = 'bar';
    ...
    this.property232 = 'bar';
  }
}

but it's not super pretty, since in my actual code I have 200 properties

CodePudding user response：

Well just add an implements MyProperties clause to the class:

interface MyProperties {
    property1: string
    property2: string
}

class MyClass implements MyProperties {
    property1: string;
    property2: string;

    constructor() {
        this.property1 = 'foo';
        this.property2 = 'bar';
    }
}

CodePudding user response：

Right now typescript will give me this error

Thats because there are no definition in class for this properties. You should tell TypeScript compiler that MyClass has this properties:

class MyClass {
    property1: string;
    property2: string;
    constructor() {
        this.property1 = 'foo';
        this.property2 = 'bar';
    }
}

Now, compiler know what properties MyClass has and can realize that MyClass implementing MyProperties interface:

interface MyProperties {
    property1: string
    property2: string
}

class MyClass {
    property1: string;
    property2: string;
    constructor() {
        this.property1 = 'foo';
        this.property2 = 'bar';
    }
}

const a: MyProperties = new MyClass(); // no error here

Also you can explicitly implement MyProperties interface to improve readability of code using implements MyProperties:

interface MyProperties {
    property1: string
    property2: string
}

class MyClass implements MyProperties {
    property1: string;
    property2: string;
    constructor() {
        this.property1 = 'foo';
        this.property2 = 'bar';
    }
}

const a: MyProperties = new MyClass(); // no error here too