Angular2 FormBuilder:在自定义验证器中使用"this" [英] Angular2 FormBuilder: Using 'this' in a custom validator

问题描述

我正在使用Angular2的FormBuilder开发带有自定义验证的表单. 问题:在customValidator中，我正在使用this访问本地对象data.执行验证时出现undefined错误.

I'm developing a form using Angular2's FormBuilder with custom validation. Problem: In customValidator I'm using this to access the local object data. I'm getting a undefined error when the validation is executed.

customValidator似乎是在另一个对象中执行的，因此更改了this引用

It looks like the customValidator is executed in a different object and therefore changing the this reference

问题:如何将this的引用传递给customValidator?

Question: How can I pass a reference of this to the customValidator?

export class Ast {
    public data:any;
    public myForm:FormGroup;

    constructor(private _fb:FormBuilder) {
        this.data = {foo: "bar"};
    }

    customValidator(c: FormControl) {
        if (this.data.foo == "bar") { // This line crashes
            // DO something
        }
    }

   ngOnInit() {
       this.myForm = this._fb.group({
           some_field: ['', [<any>Validators.required], this.customValidator]
       })
   }
}

推荐答案

使用箭头函数，以确保该函数绑定到此:

Using an arrow function, to make sure the function is bound to this:

some_field: ['', [<any>Validators.required], c => this.customValidator(c)]

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