angular - 响应式表单 valueChanges 如何仅观看 2 个字段 [Angular2]

Question

如何仅观看 Angular ReactiveForm 的 2 个字段？
我有一个如下所示的表格:

this.filter = this.fb.group({
            text: ['', []],
            bankCountry: ['', []],
            bankCity: ['', []]
        });

如何观察与最后 2 个字段相关的更改？

Answer 1

两种方式:

1、使用 combineLatest:

http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html#static-method-combineLatest

Observable.combineLatest( this.text.valueChanges, this.bankCountry.valueChanges ).subscribe(respArr => {
     console.log(respArr); //this is array with responses from both observables
});

2、使用过滤器:

http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html#instance-method-filter

this.filter.valueChanges.filter((val) => /*filter predicate returning boolean*/).subscribe(val => {
    console.log(val);
});