Directives for auto binding Input() and Output() from host component to inner in Angular9+ application

• Example
• Installation
• Links
• Usage
• Debug
• Rules for detect inputs and outputs
• Bind to dynamic components
• Work without IVY Renderer

Example

Without auto binding inputs and outputs

<component-name (start)="onStart()" [isLoading]="isLoading$ | async" [propA]="propA" [propB]="propB"> </component-name>

With auto binding inputs and outputs

<component-name [bindIO]> </component-name>

Installation

npm i --save ngx-bind-io

Links

Demo - Demo application with ngx-bind-io.

Stackblitz - Simply sample of usage on https://stackblitz.com

Usage

app.module.ts

import { NgxBindIOModule } from 'ngx-bind-io';
import { InnerComponent } from './inner.component';
import { HostComponent } from './host.component';

@NgModule({
  ...
  imports: [
    ...
    NgxBindIOModule.forRoot(), // in child modules import as "NgxBindIOModule"
    ...
  ]
  declarations: [
    ...
    InnerComponent,
    HostComponent
    ...
  ],
  ...
})
export class AppModule { }

inner.component.ts

import { ChangeDetectionStrategy, Component, EventEmitter, Input, Output } from '@angular/core';
import { BindIoInner } from 'ngx-bind-io';

@BindIoInner() // <-- need for correct detect manual inputs like [propName]="propValue"
@Component({
  selector: 'inner',
  changeDetection: ChangeDetectionStrategy.OnPush,
  template: `
    <div *ngIf="isLoading">Loading... (5s)</div>
    <button (click)="onStart()">Start</button> <br />
    {{ propA }} <br />
    {{ propB }}
  `
})
export class InnerComponent {
  @Input()
  isLoading: boolean = undefined;
  @Input()
  propA = 'Prop A: not defined';
  @Input()
  propB = 'Prop B: not defined';
  @Output()
  start = new EventEmitter();
  onStart() {
    this.start.next(true);
  }
}

base-host.component.ts

import { BehaviorSubject } from 'rxjs';

export class BaseHostComponent {
  isLoading$ = new BehaviorSubject(false);
  onStart() {
    this.isLoading$.next(true);
    setTimeout(() => this.isLoading$.next(false), 5000);
  }
}

host.component.ts

import { ChangeDetectionStrategy, Component } from '@angular/core';
import { BaseHostComponent } from './base-host.component';

@Component({
  selector: 'host',
  changeDetection: ChangeDetectionStrategy.OnPush,
  template: `
    <inner [bindIO]></inner>
  `
})
export class HostComponent extends BaseHostComponent {
  propA = 'Prop A: defined';
  propB = 'Prop B: defined';
}

Debug

For global debug all bindings

import { NgxBindIOModule } from 'ngx-bind-io';

@NgModule({
  ...
  imports: [
    ...
    NgxBindIOModule.forRoot({debug: true})
    ...
  ],
  ...
})
export class AppModule { }

For debug on one place

<comp-name [bindIO]="{debug:true}"></comp-name>

Rules for detect inputs and outputs

Custom rules for detect output method

my-ngx-bind-outputs.service.ts

import { Injectable } from '@angular/core';
import { IBindIO, NgxBindOutputsService } from 'ngx-bind-io';

@Injectable()
export class MyNgxBindOutputsService extends NgxBindOutputsService {
  checkKeyNameToOutputBind(directive: Partial<INgxBindIODirective>, hostKey: string, innerKey: string) {
    const outputs = directive.outputs;
    const keyWithFirstUpperLetter =
      innerKey.length > 0 ? innerKey.charAt(0).toUpperCase() + innerKey.substr(1) : innerKey;
    return (
      (hostKey === `on${keyWithFirstUpperLetter}` &&
        outputs.hostKeys.indexOf(`on${keyWithFirstUpperLetter}Click`) === -1 &&
        outputs.hostKeys.indexOf(`on${keyWithFirstUpperLetter}ButtonClick`) === -1) ||
      (hostKey === `on${keyWithFirstUpperLetter}Click` &&
        outputs.hostKeys.indexOf(`on${keyWithFirstUpperLetter}ButtonClick`) === -1) ||
      hostKey === `on${keyWithFirstUpperLetter}ButtonClick`
    );
  }
}

app.module.ts

import { NgxBindOutputsService, NgxBindIOModule } from 'ngx-bind-io';
import { MyNgxBindOutputsService } from './shared/utils/my-ngx-bind-outputs.service';
import { InnerComponent } from './inner.component';
import { HostComponent } from './host.component';

@NgModule({
  declarations: [AppComponent],
  imports: [
    ...
    NgxBindIOModule,
    ...
  ],
  declarations: [
    AppComponent,
    InnerComponent,
    HostComponent,
    ...
  ],
  providers: [
    ...
    { provide: NgxBindOutputsService, useClass: MyNgxBindOutputsService },
    ...
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

Default rules for detect output method

ngx-bind-outputs.service.ts

export class NgxBindOutputsService {
  ...
  checkKeyNameToOutputBind(directive: Partial<INgxBindIODirective>, hostKey: string, innerKey: string) {
    const outputs = directive.outputs;
    const keyWithFirstUpperLetter = innerKey.length > 0 ? innerKey.charAt(0).toUpperCase() + innerKey.substr(1) : innerKey;
    return (
      (hostKey === `on${keyWithFirstUpperLetter}` &&
        outputs.hostKeys.indexOf(`on${keyWithFirstUpperLetter}Click`) === -1) ||
      hostKey === `on${keyWithFirstUpperLetter}Click`
    );
  }
  ...
}

Default rules for detect inputs variables

ngx-bind-inputs.service.ts

export class NgxBindInputsService {
  ...
  checkKeyNameToInputBind(directive: Partial<INgxBindIODirective>, hostKey: string, innerKey: string) {
    return hostKey === innerKey && hostKey[0] !== '_';
  }
  ...
  checkKeyNameToObservableInputBind(directive: Partial<INgxBindIODirective>, hostKey: string, innerKey: string) {
    return hostKey === `${innerKey}$` && hostKey[0] !== '_';
  }
  ...
}

Bind to dynamic components

Becouse dynamic components not have normal lifecicle, recomendate define they without OnPush strategy.

If you want use with OnPush, you may use Inputs with BindObservable and call properties with async pipe.

Or use NgxBindIoService and run method linkHostToInner for bind inputs and outputs.

inner.component.ts

import { ChangeDetectionStrategy, Component, EventEmitter, Input, Output } from '@angular/core';
import { BindIoInner } from 'ngx-bind-io';

@BindIoInner() // <-- need for correct detect manual inputs like [propName]="propValue"
@Component({
  selector: 'inner',
  // changeDetection: ChangeDetectionStrategy.OnPush, <-- change detection with OnPush strategy incorrected work for dynamic components
  template: `
    <div *ngIf="isLoading">Loading... (5s)</div>
    <button (click)="onStart()">Start</button> <br />
    {{ propA }} <br />
    {{ propB }}
  `
})
export class InnerComponent {
  @Input()
  isLoading: boolean = undefined;
  @Input()
  propA = 'Prop A: not defined';
  @Input()
  propB = 'Prop B: not defined';
  @Output()
  start = new EventEmitter();
  onStart() {
    this.start.next(true);
  }
}

host.component.ts

import { ChangeDetectionStrategy, ChangeDetectorRef, Component, SkipSelf } from '@angular/core';
import { BaseHostComponent } from './base-host.component';
import { BehaviorSubject } from 'rxjs';
import { InnerComponent } from './inner.component';

@Component({
  selector: 'host',
  changeDetection: ChangeDetectionStrategy.OnPush,
  template: `
    <template #inner></template>
  `
})
export class HostComponent {
  @ViewChild('inner', { read: ViewContainerRef })
  inner: ViewContainerRef;

  propA = 'Prop A: defined';
  propB = 'Prop B: defined';
  isLoading$ = new BehaviorSubject(false);

  constructor(
    private _ngxBindIoService: NgxBindIoService,
    @SkipSelf()
    private _parentInjector: Injector,
    private _changeDetectorRef: ChangeDetectorRef,
    private _resolver: ComponentFactoryResolver
  ) {
    this.createInner();
  }
  createInner() {
    this.inner.clear();
    const factory = this._resolver.resolveComponentFactory(InnerComponent);
    const componentRef = this.inner.createComponent(factory);
    this._ngxBindIoService.linkHostToInner(
      this,
      componentRef.instance,
      { propA: this.propA, propB: this.propB },
      this._parentInjector,
      this._changeDetectorRef
    );
  }
  onStart() {
    this.isLoading$.next(true);
    setTimeout(() => this.isLoading$.next(false), 5000);
  }
}

Work without IVY Renderer

For correct work without IVY Renderer, all inner Inputs, Outputs and all host properties ​​must be initialized, you can set them to "undefined".

For check project ready to use bindIO directives, you may use ngx-bind-io-cli and run:

npx ngx-bind-io-cli ./src --maxInputs=0 --maxOutputs=0

For check and add initialize statement:

npx ngx-bind-io-cli ./src --fix=all --maxInputs=0 --maxOutputs=0

For check and add initialize statement if you want correct work with tspath:

npx ngx-bind-io-cli ./src --fix=all --maxInputs=0 --maxOutputs=0  --tsconfig=./src/tsconfig.app.json

License

MIT