Validation 角度8-FormControl模式验证

我正在尝试仅用字母验证用户字段。 遵循

https://angular.io/api/forms/Validators#pattern

我没有得到预期的结果

验证器。必需的工作。 Validator.minLength有效。 但模式并非如此

我需要用户字段只有字母。 已经在论坛中查找了类似的问题，并尝试了一些实现，但不起作用

我还尝试将direct添加到html标记

[pattern]='onlyleters'

，但也没有成功

html

}

我在这里再试一次。

<form (ngSubmit)="onSubmitNewUser()" [formGroup]="userFormGroup" >
    <mat-card>

        <mat-card-title fxLayoutAlign="center">{{'USERS.NEW'|translate}}</mat-card-title>
        <mat-card-content fxLayoutAlign="left" fxLayout="column">

            <mat-form-field fxFlex="100%">
                <mat-label>{{'USERS.GROUP'|translate}}</mat-label>
                <mat-select  formControlName="group" >
                    <mat-option *ngFor="let group of groups" value="{{ group.users_group_id }}">{{ group.users_group_name }}</mat-option>
                </mat-select>
            </mat-form-field>

            <mat-form-field fxFlex="100%">
                <input
                    [pattern]="pattern"
                    placeholder="{{'USERS.USERNAME'|translate}}"
                    type="text"
                    formControlName="username"
                    matInput />
                <mat-error *ngIf="formControlUsername.hasError('required')" >
                    {{'VALIDATION.REQUIRED'|translate}}
                </mat-error>
            </mat-form-field>

            <mat-form-field fxFlex="250px" hintLabel="{{'VALIDATION.PASSWORD_HINT'|translate}}">
                <input
                    type="password"
                    placeholder="{{'USERS.PASSWORD'|translate}}"
                    matInput
                    formControlName="password"/>
                <mat-hint align="end"> {{ formControlPassword.value?.length }}  / 6 </mat-hint>
                <mat-error>{{'VALIDATION.MIN_LENGTH'|translate}}</mat-error>
            </mat-form-field>

        </mat-card-content>

        <mat-card-actions fxLayoutAlign="left">
            <button
                type="submit"
                color="primary"
                mat-raised-button
                [disabled]="userFormGroup.invalid">{{'SAVE'|translate}}</button>
        </mat-card-actions>
    </mat-card>

</form>

import { Component, OnInit} from '@angular/core';
import { FormControl, FormGroup, Validators} from '@angular/forms';
import { GroupsModel} from '../_models/groups.model';
import { UsersService} from '../_services/users.service';

@Component({
  selector: 'app-users-add',
  templateUrl: './users-add.component.html',
  styleUrls: ['./users-add.component.scss']
})
export class UsersAddComponent implements OnInit {

pattern = "[a-zA-Z]*";

formControlGroup    = new FormControl('',{
    validators: [Validators.required]
});

formControlUsername = new FormControl('',{
    validators: [
        Validators.required,
        Validators.pattern(this.pattern)
    ]
});

formControlPassword = new FormControl('',{
    validators: [
        Validators.required,
        Validators.minLength(6)
    ]
});

userFormGroup: FormGroup;

groups: GroupsModel[] = [];

constructor(private usersService: UsersService) { }

ngOnInit() {

    this.userFormGroup = new FormGroup({
        group: this.formControlGroup,
        username: this.formControlUsername,
        password: this.formControlPassword
    });

    this.usersService.getGroups().subscribe( data => {
        this.groups = data
    });
}

onSubmitNewUser() {
    console.log(this.userFormGroup.value);
}