angular / angular/components

feat(mat-form-field): simplified errorstatematcher

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area: material/form-field feature P3
Langage dominant
TypeScript
Étoiles
25k
Forks
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Merge moyen
1 j 8 h
PR mergées (30 j)
91

Description

### Feature Description

I've got a simple input field that just uses an ngModel for a username and password, and on error uses a signal for error state.

I would like to use signals to update the form's error state, but it seems like I need to bind an errorStateMatcher to a boring, repetitive throwaway chunk of code in my controller, because errorStateMatcher isn't just a boolean thing, it's an object that has one property (isErrorState) that is a function that takes some arguments etc. This is some java masquerading as typescript if I ever saw it (editorializing over).

### Use Case

```
class LoginControl {
username = '';
password = '';
status = signal({username: false, password: false});
async tryLogin() {
try {
await doSomeLogin(this.username, this.password);
} catch (e) {
if (e.badPassword) {
this.status.set({username: false, password: true});
// etc
```

in my template:

```

Password

^^^ what I want (or [simpleErrorState] if you don't want me overriding something important
woops

```

what I do instead is have to make

```
passwordInvalid = {
isErrorSate: () => this.error().password,
};
```

on my controller and boy howdy is that bad ergonomics. It's repetitive, and more importantly it obscures the real nature of the value. What if I accidentally do the wrong error property in the controller method? easy mistake to make when copy-pasting and hard to notice when the inlined value is not there.

As far as I can tell, the only reason this is the case is that we want to pass some lambda to the errorstatematcher, but it would *really* be great if these shiny new input signals and stuff would handle this.

Yes, I know I can just make a formgroup and write a reactive form. That's overkill and a ton of extra crust for two fields and a button.

AS AN ALTERNATIVE, I would accept: presence of a mat-error in the formfield automatically sets errorState to true, and then I can just wrap all these in `@if (error().email) { woops }` sorts of things. Based on the number of yaqs... i mean stack overflow comments I've seen about this, it seems like this is what a lot of developers think the behavior should be anyway. I'll admit that I thought the same thing. It's a little odd, having an API defined by "what child elements are in your tree" but you opened that door when you made mat-form-fields bind garbage on the child form input element. Not that I can think of a better approach here, honestly.

Guide de contribution

Ouvrir le guide de contribution

Piste de recherche

Commencez par l’API errorStateMatcher de mat-form-field et comparez-la avec l’utilisation dans le template et le contournement dans le contrôleur présentés dans l’issue. Déterminez quel comportement d’API proposé devrait être pris en charge, puis vérifiez qu’un état d’erreur booléen piloté par un signal peut être exprimé sans l’objet matcher répétitif et que l’alternative mat-error se comporte comme prévu.

Rédigé par le modèle d'indexation à partir du texte de l'issue.

Évaluation

Stack technique
angular, typescript
Domaine
frontend
Type d'issue
Fonctionnalité
Difficulté
5/5
Temps estimé
Plus d'une semaine
Activité
À l'abandon
Clarté
Plutôt claire
Accessibilité débutants
35/100

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