typescript Angular 4：setValue formBuilder 空数组
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Angular 4: setValue formBuilder empty array
提问by brabertaser19
I have such reactive form:
我有这样的反应形式：
constructor(...){
this.form = this.formBuilder.group({
name: ['', Validators.compose([Validators.required, Validators.maxLength(50)])],
memes: this.formBuilder.array([
this.initMemes('TrollFace')
])
});
}
initMemes (name?) {
return this.formBuilder.group({
id: [''], name: [name]
});
}
later i can add some more memes:
稍后我可以添加更多memes：
addMemes () {
const control = <FormArray>this.form.controls['memes'];
control.push(this.initMemes('anyName'));
}
and then if i get form values i get:
然后如果我得到表单值，我会得到：
this.form.controls['memes'].value- here i have array
this.form.controls['memes'].value- 这里我有数组
But there is a case, when i need this this.form.controls['memes'].valueto set to an empty array, how is it possible to do?
但是有一种情况，当我需要将this.form.controls['memes'].value其设置为空数组时，怎么办？
If i set it this way:
如果我这样设置：
this.form.controls['memes'].setValue([])
this.form.controls['memes'].setValue([])
I got error: Must supply a value for form control at index: 0.
我有错误： Must supply a value for form control at index: 0.
what i do wrong?
我做错了什么？
回答by AJT82
EDIT:
编辑：
As of newer versions, Angular now supports clearing a FormArraywith clear():
在新的版本中，角现在支持清除FormArray有clear()：
(<FormArray>this.form.get('memes')).clear();
ORIGINAL:
原来的：
Tried a few things:reset(),setControl(), but the following was the only solution I found to work that actually resets the whole array to [], other options worked, but they left the formgroups in place, just emptied the values.
尝试了一些事情：reset(), setControl()，但以下是我发现的唯一可行的解决方案，它实际上将整个数组重置为[]，其他选项有效，但他们将表单组留在原地，只是清空了值。
So how I got it to work, was to iterate the form array and delete each form group with that particular index in the loop:
所以我如何让它工作，是迭代表单数组并删除循环中具有该特定索引的每个表单组：
const control = <FormArray>this.form.controls['memes'];
for(let i = control.length-1; i >= 0; i--) {
control.removeAt(i)
}
If there is a better way, I'm open for suggestions! :)
如果有更好的方法，我愿意接受建议！:)
回答by Jacob Kochocki
Try this.myForm.controls['myFormArray'] = this.formBuilder.array([]);with formBuilder service instantiated in your constructor.
尝试this.myForm.controls['myFormArray'] = this.formBuilder.array([]);在构造函数中实例化 formBuilder 服务。
回答by Luis Ricardo Cayetano Herrera
FORM
形式
this.form = this._formB.group({
blocks: this._formB.array([])
});
1st method
第一种方法
let fArray = <FormArray>this.form.controls['blocks'];
while (fArray.length !== 0) {
fArray.removeAt(0)
}
2nd method
方法二
this.form.setControl('blocks', this._formB.array([]));
回答by Sam
I was having a similar issue, where I would get said error after updating my form, and after a bunch of investigation and failed experimentation I found that this.myForm.updateValueAndValidityfinally did the trick.
我遇到了类似的问题，在更新表单后我会收到上述错误，经过大量调查和失败的实验，我发现this.myForm.updateValueAndValidity最终成功了。
