Forms with ngrx, NativeScript, and Angular

There are many ways to make forms in Angular. There’s template driven, reactive, and the question of syncing with ngrx state or keeping the it local to the component. When making a NativeScript app it’s not always obvious how to reuse these forms. For example, template driven forms in Angular might use the dom’s “required” attribute.  NativeScript doesn’t have a dom or input component at all, so the required logic would have to be remade, perhaps using a required directive. Redux/ngrx driven forms offer a significant advantage when we have multiple platforms as ngrx is platform agnostic and we can perform the validation logic in the reducer instead of the component or a directive.

As a case study, I recently rewrote Passit’s login form with the fantastic ngrx-forms package. ngrx-forms takes care of common use cases while providing a blueprint and examples of how to make the state driven forms.

login
The validation logic is in the reducer, here two different platforms show the errors that get pulled from state

Using ngrx-forms on the web is straight-forward, just follow the docs. For NativeScript you’ll have to make a few changes:

  • There is no “form” component in NativeScript, so you’ll have to manage isSubmitted yourself. You could modify the submit state in the reducer itself or in the component with MarkAsSubmittedAction.
  • ngrx-forms comes with directives to keep the form and ngrx data in sync. But these won’t work out of the box with NativeScript components. Here is a NgrxTextFieldViewAdapter for a TextInput. Just add the directive like [ngrxFormControlState]=”form.controls.yourField” and the TextInput state will sync with the form state, just like on the web.

Now I can reuse all of my form validation logic in both platforms. The only difference is the presentational components for app and web.

Overall I think ngrx-forms offers a straight forward, redux friendly, and platform agnostic solution to forms. Please feel free to take a look at my Android preview release of Passit, the open source password manager. As I create more forms on both platforms I’m looking forward to having a single strategy for building them. Be sure to report bugs on gitlab.

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