[英]How to implement Conditional required validation in angular forms?
如果两个字段都没有输入,那么两者都可以是可选的。 如果 firstname 已输入,则根据需要设置 lastname。 如果 lastname 有输入但 firstname 没有输入,则根据需要设置 firstname。
如果一个字段有值而另一个字段没有值,则根据需要设置其他字段。 谢谢你。
所以就像我是用户并且有两个字段,即名字和姓氏。 如果我在名字上输入数据但姓氏为空,则根据需要设置姓氏(反之亦然)。 任何想法? 谢谢
HTML
<div fxLayout="row" fxLayoutGap="24px" formGroupName="person">
<div fxFlex fxLayout="row">
<mat-form-field appearance="outline" class="pr-4" fxFlex>
<mat-label>Firsname</mat-label>
<input matInput #firstname formControlName="firstname" trim required/>
<button type="button" mat-button *ngIf="firstname.value" matSuffix mat-icon-button aria-label="Clear"
(click)="clearFieldFirstname()">
<mat-icon>close</mat-icon>
</button>
</mat-form-field>
</div>
<div fxFlex fxLayout="row">
<mat-form-field appearance="outline" class="pr-4" fxFlex>
<mat-label>Lastname</mat-label>
<input matInput #lastname formControlName="lastname" trim required/>
<button type="button" mat-button *ngIf="lastname.value" matSuffix mat-icon-button aria-label="Clear"
(click)="clearFieldLastname()">
<mat-icon>close</mat-icon>
</button>
</mat-form-field>
</div>
</div>
TS 代码
const personGroup = this.formBuilder.group({
firstName: [person.firstName, Validators.required],
lastName: [person.lastName, Validators.required],
});
const formGroup = this.formBuilder.group({
person: personGroup,
});
this.person.get("firstname").valueChanges.subscribe(value => {
const lastName = this.person.get("lastname");
lastName.clearValidators();
if (value && !lastName.value) {
lastName.setValidators(Validators.required);
}
lastName.updateValueAndValidity({
emitEvent: false
});
});
this.person.get("lastname").valueChanges.subscribe(value => {
const firstName = this.person.get("firstname");
if (value && !firstName.value) {
firstName.setValidators(Validators.required);
} else {
firstName.clearValidators();
}
firstName.updateValueAndValidity({
emitEvent: false
});
});
const personGroup = this.formBuilder.group({
firstName: [
person.firstName,
(control: AbstractControl): ValidationErrors | null => {
// do your validation logic here:
if (this.formGroup?.get('lastName').value) {
if (!control.value) {
return {required: true};
}
}
// all is fine:
return null;
}
],
lastName: [
person.lastName,
(control: AbstractControl): ValidationErrors | null => {
if (this.formGroup?.get('firstName').value) {
if (!control.value) {
return {required: true};
}
}
return null;
}
],
});
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