我想制作自定义验证器，只有当表单中的文本是唯一的时，它才会使提交按钮可用。我有 VulnarabilitiesClass 实例，它包含一个带有 id 和 name 字段的对象数组。在我的表单中输入任何文本后，我收到此错误：错误：未定义不是对象（评估“this.systemVulnarabilities”）
<form [formGroup]="profileForm">
<label>
Vulnarability Name:
<input type="text" formControlName="name" required>
</label>
</form>
<p>
Form Status: {{ profileForm.status }}
</p>
<form [formGroup]="profileForm" (ngSubmit)="onSubmit()">
<button type="submit" [disabled]="!profileForm.valid">Submit</button>
this.systemVulnarabilities = new VulnarabilitiesClass();
profileForm = this.fb.group({
name: ['', Validators.required,this.UniqueNameValidator],
});
private UniqueNameValidator(control: FormControl): ValidationErrors{
let vulnarabilityName: string = control.value;
console.log(vulnarabilityName);
console.log(this.systemVulnarabilities.displayList.toString());//no output already
let found: number = this.systemVulnarabilities.displayList.map(function(e) { return e.name; }).indexOf(vulnarabilityName); //mistake
if(found === -1){
return {invalidPassword: 'this name already exists'};
}
return null;
}