将 FormArray 转换为数组角度

Question

I have a FormArray of FormGroups, i want to iterate over the FormArray and detect which FormGroups are valid. However i am unable to do so as i am unable to iterate over a FormArray as it is not of type Array or string. My logic was to somehow cast the FormArray into an Array if possible. However i do not know the syntax in typescript for this.

 this.applicationFormArray = new FormArray([ this.selectAppFormGroup = new FormGroup({ }), this.generalAppFormGroup = new FormGroup({ }), this.fileModeFormGroup = new FormGroup({ }), this.accessListFormGroup = new FormGroup({ }), ]);

 checkValidity() { var foo = this.applicationFormArray as Array<>; for(var element of this.applicationFormArray){ if(element.valid) { //do something } }

Answer 1

You can use map together with the length of FromArray and the at method:

let array = new Array(this.applicationFormArray.length)
    .map((v, index) => this.applicationFormArray.at(index) as FormGroup);

Although the for version is not too bad either:

for (let i =0;i< this.applicationFormArray.length;i++) {
    const element = this.applicationFormArray.at(i);
    if (element.valid) {
        //do something
    }
}

Answer 2

一种可能的解决方案是使用过滤器并仅获取有效表格。

const myValidForms = formArray.controls.filter(myForm => myForm.valid);

Answer 3

You can convert a FormArray to a regular Array with the FormArray's value property. This is what worked for me. Using the value property on a FormGroup returns an object literal and on a FormArray it returns an array.

let newArr = this.applicationFormArray.value
newArr.map(...)

In your example it would look like this:

var foo = this.applicationFormArray.value;
for(var element of foo){
   if(element.valid) {
       //do something
    }
}

Answer 4

Try using foreach instead of

this.applicationFormArray.forEach(element => {
    if(element.valid) {
        //do something
    }    
});