当FormArray为空时，FormArray应无效

Question

我使用FormArray创建了如下所述的表单

    this.createModuleForm = this.fb.group({
        artefactType: ['', Validators.required],
        uploadDocuments: this.fb.array([]),
    });

然后我将对象推到FormArray中

        formArray.push(this.fb.group({name: event.name, url: event.url, submittedBy: 'siva', role: this.currentUser.value.role}));

问题:如果uploadDocuments(FormArray)为空，则需要使表单无效，而UploadDocuments应是强制数据

Answer 1

创建自定义Validator

我已经创建了minAdded函数来检查wheather当前的格式数组至少有一个组或没有

component.ts

 this.createModuleForm = this.fb.group({
        artefactType: 'De',
        uploadDocuments: this.fb.array([], minAdded(1))
 })

    function minAdded(min = 1) {
      const validator: ValidatorFn = (formArray: FormArray) => {
        const minAdded = formArray.controls
          .map(control => control.value).length;    
        return minAdded >= min ? null : { required: true };
      };    
   return validator;
 }

参考：https://coryrylan.com/blog/creating-a-dynamic-checkbox-list-in-angular示例：https://stackblitz.com/edit/angular-dcy9z9