I am new to Angular and JavaScript overall, I'm trying to add messages when user input is wrong using the Materialize library (the data-error attribute). So my html component looks like this:
<input
type="text"
id="username"
formControlName="username"
[class.valid]="username?.valid && username.dirty"
[class.invalid]="!username?.valid && username.dirty && !username.pending"
>
<label for="username"
data-error="ERROR_MESSAGE" // <-- this is what I need to work
>Username</label>
I want to change the data-error attribute depending on the error present. Right now it will print "ERROR_MESSAGE" on any error present. I tried writing a function and binding it with [attr.data-error] like this:
displayUsernameErrorMessage() {
let message = '';
let usernameError = this.username.errors;
if(usernameError.pattern){
message = "Invalid Username"
console.log(usernameError);
}
else {
return null;
}
}
I think I'm doing a really bad job with this, the function logs like 10 times in the console and it's a poor solution. Any ideas on how to make it work better are greatly appreciated!
EDIT 1: Additional info is that I want to display different messages depending on the error. So if I get an error from the Validator.pattern - I want the message to be something like "Invalid username" or if it's from Validators.required - "Please insert a username", something like that.
That's how I'm doing it (adapted to your Exemple):
<form name="nameForm" [formGroup]="nameForm">
<fieldset>
<label for="username">Username</label>
<input
required
id="username"
formControlName="username"
>
<span
class="text-danger"
[hidden]="nameForm.controls.name.valid || itemForm.controls.name.pristine"
>
<small>{{'Please enter your name'}}</small>
</span>
</fieldset>
</form>
In your TS file :
import { FormGroup, FormBuilder, FormControl, Validators } from '@angular/forms';
export class InputComponent {
public nameForm: FormGroup;
constructor(private formBuilder: FormBuilder) {
this.nameForm = this.formBuilder.group({
username: new FormControl('', Validators.required),
});
}
//... codes..
}
Where you can customize the text-danger
in your CSS
(or any alternative) file
I needed to do something like this as well so I ended up writing a directive that can be placed on <label>
elements.
In your example it would look like this:
<label for="username" errorMessageForFormControl>Username</label>
<input required id="username" formControlName="username">
I wanted to avoid repeating the control name twice so the directive looks at the value of the for
attribute and finds the control from that. If your FormControls and <input>
field IDs happen to not match up you can set it yourself.
<label for="somethingDifferent" errorMessageForFormControl="username">Username</label>
<input required id="somethingDifferent" formControlName="username">
The directive ended up looking like this:
import { Directive, Host, HostBinding, Input, Optional, OnInit, SkipSelf } from '@angular/core';
import { AbstractControl, ControlContainer } from '@angular/forms';
@Directive({
selector: '[errorMessageForFormControl]'
})
export class errorMessageDirective implements OnInit {
@HostBinding('class.validation-error') validationErrorCssClass = false;
@HostBinding('attr.data-error') errorMessage: string = null;
@Input() public errorMessageForFormControl: string;
@Input() public for: string;
private ctrl: AbstractControl = null;
constructor(
@Optional() @Host() @SkipSelf()
private controlContainer: ControlContainer
) { }
public ngOnInit(): void {
if (!this.controlContainer) {
return;
}
const formControlName = this.errorMessageForFormControl || this.for;
if (formControlName) {
this.ctrl = this.controlContainer.control.get(formControlName);
}
if (this.ctrl) {
this.ctrl.statusChanges.subscribe(statusText => {
if (statusText === 'INVALID') {
// invalid
const errors = this.ctrl.errors;
if (errors) {
const errKey = Object.keys(errors)[0];
const errVal = errors[errKey];
this.errorMessage = errVal === true ? errKey : errVal;
} else {
this.errorMessage = 'validation failed';
}
this.validationErrorCssClass = true;
} else {
// valid
this.errorMessage = null;
this.validationErrorCssClass = false;
}
});
}
}
}
And you can refer to the data-error attribute in some css
[data-error].validation-error::after {
color:red;
content: attr(data-error);
opacity: 0.8;
font-weight: bold;
font-style: italic;
font-size: 0.75em;
margin-right: 0.25em;
z-index: 99;
float: right;
transform: translateY(85%);
}
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