Forms

Often when building Reactive Forms in Angular, you need to bind values from the store to the form and vice versa. The values from the store are observable and the reactive form accepts raw objects, as a result we end up monkey patching this back and forth.
In addition to these issues, there are workflows where you want to fill out a form and leave and then come back and resume your current status. This is an excellent use case for stores and we can conquer that case with this plugin.
In a nutshell, this plugin helps to keep your forms and state in sync.
Installation
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npm install @ngxs/form-plugin --save
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​
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# or if you are using yarn
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yarn add @ngxs/form-plugin
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Usage
In the root module of your application, import NgxsFormPluginModule and include it in the imports.
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import { NgxsFormPluginModule } from '@ngxs/form-plugin';
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import { NovelsState } from './novels.state';
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​
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@NgModule({
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  imports: [NgxsModule.forRoot([NovelsState]), NgxsFormPluginModule.forRoot()]
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})
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export class AppModule {}
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If your form is used in a submodule, it must be imported there as well:
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import { NgxsFormPluginModule } from '@ngxs/form-plugin';
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​
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@NgModule({
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  imports: [NgxsFormPluginModule]
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})
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export class SomeModule {}
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Form State
Define your default form state as part of your application state.
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import { Injectable } from '@angular/core';
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import { State } from '@ngxs/store';
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​
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@State({
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  name: 'novels',
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  defaults: {
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    newNovelForm: {
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      model: undefined,
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      dirty: false,
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      status: '',
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      errors: {}
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    }
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  }
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})
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@Injectable()
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export class NovelsState {}
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Form Setup
In your component, you would implement the reactive form and decorate the form with the ngxsForm directive with the path of your state object. We are passing the string path to ngxsForm. The directive uses this path to connect itself to the store and setup bindings.
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import { Component } from '@angular/core';
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import { FormGroup, FormControl } from '@angular/forms';
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​
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@Component({
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  selector: 'new-novel-form',
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  template: `
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    <form [formGroup]="newNovelForm" ngxsForm="novels.newNovelForm" (ngSubmit)="onSubmit()">
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      <input type="text" formControlName="novelName" />
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      <button type="submit">Create</button>
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    </form>
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  `
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})
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export class NewNovelComponent {
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  newNovelForm = new FormGroup({
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    novelName: new FormControl()
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  });
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​
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  onSubmit() {
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    //
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  }
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}
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Now anytime your form updates, your state will also reflect the new state.
The directive also has two inputs you can utilize as well:
ngxsFormDebounce: number - Debounce the value changes to the form. Default value: 100. Ignored if updateOn is blur or submit.
ngxsFormClearOnDestroy: boolean - Clear the state on destroy of the form.
Actions
In addition to it automatically keeping track of the form, you can also manually dispatch actions for things like resetting the form state. For example:
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this.store.dispatch(
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  new UpdateFormDirty({
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    dirty: false,
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    path: 'novels.newNovelForm'
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  })
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);
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The form plugin comes with the following actions out of the box:
UpdateFormStatus({ status, path }) - Update the form status
UpdateFormValue({ value, path, propertyPath? }) - Update the form value (or optionally an inner property value)
UpdateFormDirty({ dirty, path }) - Update the form dirty status
SetFormDisabled(path) - Set the form to disabled
SetFormEnabled(path) - Set the form to enabled
SetFormDirty(path) - Set the form to dirty (shortcut for UpdateFormDirty)
SetFormPristine(path) - Set the form to pristine (shortcut for UpdateFormDirty)
ResetForm({ path, value? }) - Reset the form with or without the form value.
Updating Specific Form Properties
The form plugin exposes the UpdateFormValue action that provides the ability to update nested form properties by supplying a propertyPath parameter.
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interface NovelsStateModel {
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  newNovelForm: {
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    model?: {
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      novelName: string;
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      authors: {
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        name: string;
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      }[];
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    };
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  };
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}
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​
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@State<NovelsStateModel>({
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  name: 'novels',
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  defaults: {
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    newNovelForm: {
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      model: undefined
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    }
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  }
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})
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@Injectable()
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export class NovelsState {}
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The state contains information about the new novel name and its authors. Let's create a component that will render the reactive form with bounded ngxsForm directive:
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import { Component } from '@angular/core';
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import { FormBuilder, FormGroup } from '@angular/forms';
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​
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@Component({
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  selector: 'new-novel-form',
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  template: `
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    <form [formGroup]="newNovelForm" ngxsForm="novels.newNovelForm" (ngSubmit)="onSubmit()">
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      <input type="text" formControlName="novelName" />
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      <div
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        formArrayName="authors"
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        *ngFor="let author of newNovelForm.get('authors').controls; index as index"
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      >
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        <div [formGroupName]="index">
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          <input formControlName="name" />
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        </div>
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      </div>
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      <button type="submit">Create</button>
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    </form>
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  `
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})
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export class NewNovelComponent {
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  newNovelForm: FormGroup;
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​
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  constructor(private fb: FormBuilder) {
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    this.newNovelForm = this.fb.group({
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      novelName: 'Zenith',
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      authors: this.fb.array([
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        this.fb.group({
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          name: 'Sasha Alsberg'
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        })
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      ])
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    });
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  }
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​
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  onSubmit() {
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    //
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  }
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}
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Let's look at the component above again. Assume we want to update the name of the first author in our form, from anywhere in our application. The code would look as follows:
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store.dispatch(
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  new UpdateFormValue({
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    path: 'novels.newNovelForm',
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    value: {
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      name: 'Lindsay Cummings'
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    },
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    propertyPath: 'authors.0'
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  })
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);
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Contents
Updating Specific Form Properties