ReactiveForm 用于动态更新的表单条目 [英] ReactiveForm for dynamically updated form entries

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本文介绍了ReactiveForm 用于动态更新的表单条目的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

如何在组件中检查myform的状态以检查是否所有字段都已填写?

HTML:

<div *ngFor="let question of questions"><label>{{question.question}}</label><选择需要的><option selected disabled="disabled">Option</option><option *ngFor="let option of question['options']">{{option}}</option></选择>

来自 API 的问题 JSON:

 this.questions = [{问题:'你的年龄是多少?'，选项:['20'、'30'、'40']},{问题:'多少数量?'，选项:['1','2','3']}]

解决方案

如果使用 ReactiveForm，则需要使用 FormArrayFormArray 可以是 FormControl 或 FormGroup

FormControls 的 FormArray

constructor(private fb:FormBuilder) {}ngOnInit() {//我们创建一个FormControl数组，每个问题一个FormControl让数据:FormControl[]=this.questions.map(q=>new FormControl());this.myform=this.fb.group({问题:新 FormArray(数据)})}//.html<!--我们仅在创建表单时使用 *ngIf 来显示表单--><div *ngIf="myform" [formGroup]="myform"><!--我们迭代到 myForm.get('questions').controls --><!--我们使用变量questions"来显示标签和选项--><div *ngFor="let question of myform.get('questions').controls;let i=index"><label>{{questions[i].question}}</label><选择需要的 [formControl]="问题" ><option value="null" disabled="disabled">Option</option><option *ngFor="let option of questions[i].options">{{option}}</option></选择>

<!--仅供检查-->{{myform?.value |json}}

如果我们使用一个 formGroup 数组，我们会改变一些东西

constructor(private fb:FormBuilder) {}ngOnInit() {//我们创建FormGroup数组让 data2:FormGroup[]=this.questions.map(q=>this.fb.group({选项:空}));this.myform2=this.fb.group({问题:新 FormArray(data2)})}<div *ngIf="myform2" [formGroup]="myform2"><!--看我们对 Angular 说formArrayName"--><div formArrayName="问题"><div *ngFor="let question of myform2.get('questions').controls;let i=index" [formGroupName]="i"> <!--不要忘记 formGroupName--><label>{{questions[i].question}}</label><!--select使用formControlName，我们的数组是FormGroup的数组--><选择需要的formControlName="option" ><option value="null" disabled="disabled">Option</option><option *ngFor="let option of questions[i].options">{{option}}</option></选择>

{{myform2?.value |json}}

声明:@FrontEndDeveloper.一件事是我们用来提出问题的数组问题.(Perhafs 我必须为变量选择其他名称)，另一件事是表单的值.myform1={questions:["20","1"]} 的值，myform2={questions:[{option:"20"},{option:"2"}]} 的值.

当我们创建一个 FormControl 数组(或一个 FbGroup 数组)时，我使用了 map，同样我可以做一些类似的事情

let data:FormControl[]=[];data.push(new FormControl());data.push(new FormControl());

或

let data2:FormGroup[]=[];data2.push(this.fb.group({选项:空}));data2.push(this.fb.group({选项:空}));

通常我们有一些数据来初始化表单.(一个带有一些数据的对象)我们从 dbs 中获得

//假设我们有 mydata{name:"A",options=["20","1"]}//我们可以映射这些数据来创建表单让数据:FormControl[]=this.mydata.options.map(q=>new FormControl(q));//或者让 data2:FormGroup[]=this.mydata.options.map(q=>this.fb.group({选项:q}));//假设我们有 mydata{name:"A",options=[{option:"20"},{option:"1"}]}//我们可以映射这些数据来创建表单让数据:FormControl[]=this.mydata.options.map(q=>new FormControl(q.option));//或者让 data2:FormGroup[]=this.mydata.options.map(q=>this.fb.group({选项:q.option}));

How to check status of myform in component to check if all the fields are filled or not?

HTML:

<div  [formGroup]="myform">
  <div *ngFor="let question of questions">
      <label>{{question.question}}</label>
                <select required >
                  <option selected disabled="disabled">Option</option>
                   <option *ngFor="let option of question['options']">{{option}}</option>
                </select>
            </div>
        </div>
</div>

Question JSON coming from API:

 this.questions =  [
        {
          question: 'What is your age?',
          options: ['20', '30', '40']
        },

        {
          question: 'How much quantity?',
          options: ['1','2','3']
        }]

解决方案

If you use ReactiveForm, you need use a FormArray A FormArray can be of FormControl or a FormGroup

FormArray of FormControls

constructor(private fb:FormBuilder) {}
ngOnInit() {
    //We create an array of FormControl, each question a FormControl
    let data:FormControl[]=this.questions.map(q=>new FormControl());

    this.myform=this.fb.group({
      questions:new FormArray(data)
    })
}
//the .html
<!--we use *ngIf to show the form only when we create the form-->
<div *ngIf="myform"  [formGroup]="myform">
  <!--we iterate to myForm.get('questions').controls -->
  <!--we use our variable "questions" to show the label and options-->
  <div *ngFor="let question of myform.get('questions').controls;let i=index">
      <label>{{questions[i].question}}</label>
      <select required [formControl]="question" >
         <option value="null" disabled="disabled">Option</option>
         <option *ngFor="let option of questions[i].options">{{option}}</option>
      </select>
  </div>
</div>
<!--just for check-->
{{myform?.value |json}}

If we use an array of formGroup we change some things

constructor(private fb:FormBuilder) {}
ngOnInit() {
    //we create and array of FormGroup
    let data2:FormGroup[]=this.questions.map(q=>this.fb.group({
      option:null
    }));

    this.myform2=this.fb.group({
      questions:new FormArray(data2)
    })
}
<div *ngIf="myform2"  [formGroup]="myform2">
  <!--see that we say to Angular the "formArrayName" -->
  <div formArrayName="questions">
    <div *ngFor="let question of myform2.get('questions').controls;
        let i=index" [formGroupName]="i"> <!--don't forget formGroupName-->
        <label>{{questions[i].question}}</label>
        <!--the select use formControlName, our array is an array of FormGroup-->
        <select required formControlName="option" >
           <option value="null" disabled="disabled">Option</option>
           <option *ngFor="let option of questions[i].options">{{option}}</option>
        </select>
    </div>
  </div>
  </div>
  {{myform2?.value |json}}

Aclaration:@FrontEndDeveloper. One thing is the array question that we use to make the questions.(Perhafs I must be choose other names to the variables), other thing is the value of the form. The value of myform1={questions:["20","1"]}, the value of myform2={questions:[{option:"20"},{option:"2"}]}.

When we create an array of FormControl (or an array of FbGroup) I used map, equally I can do some like

let data:FormControl[]=[];
data.push(new FormControl());
data.push(new FormControl());

or

let data2:FormGroup[]=[];
data2.push(this.fb.group({
          option:null
        }));
data2.push(this.fb.group({
          option:null
        }));

Generally we have some data to initialize the form. (an object with some data) that we get from a dbs

//Imagine we have mydata{name:"A",options=["20","1"]}
//we can map this data to create the form
let data:FormControl[]=this.mydata.options.map(q=>new FormControl(q));
//or
   let data2:FormGroup[]=this.mydata.options.map(q=>this.fb.group({
          option:q
        }));

//Imagine we have mydata{name:"A",options=[{option:"20"},{option:"1"}]}
//we can map this data to create the form
let data:FormControl[]=this.mydata.options.map(q=>new FormControl(q.option));
//or
   let data2:FormGroup[]=this.mydata.options.map(q=>this.fb.group({
          option:q.option
        }));

这篇关于ReactiveForm 用于动态更新的表单条目的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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