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Angular2 RC5: Can't bind to 'Property X' since it isn't a known property of 'Child Component'

I have a small Angular2 project based on the Angular2 Seed project that I am trying to upgrade to Angular2 RC5.

My project has a few features, one of them called home. Home component uses a child component called create-report-card-form. I have declared both the home and create-report-card-form components in the home.module (see code below) and get this error:

Unhandled Promise rejection: Template parse errors: Can't bind to 'currentReportCardCount' since it isn't a known property of 'create-report-card-form'. If 'create-report-card-form' is an Angular component and it has 'currentReportCardCount' input, then verify that it is part of this module.

Project structure

-app
    - app.module.ts
    - app.component.ts
    - +home
        - home.module.ts 
        - home.component.ts
        - home.component.html
        - create-report-card-form.component.ts
        - create-report-card-form.component.html
    - +<other "features">
    - shared
        - shared.module.ts

home.module

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import {ReactiveFormsModule} from '@angular/forms';

import { SharedModule } from '../shared/shared.module';
import { DataService } from '../shared/services/index';
import { HomeComponent } from './home.component';
import { CreateReportCardFormComponent } from './create-report-card-form.component';

@NgModule({
    imports: [CommonModule, SharedModule, ReactiveFormsModule],
    declarations: [HomeComponent, CreateReportCardFormComponent],
    exports: [HomeComponent, CreateReportCardFormComponent],
    providers: [DataService]
})

export class HomeModule { }

app.module

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { APP_BASE_HREF } from '@angular/common';
import { RouterModule } from '@angular/router';
import { HttpModule } from '@angular/http';
import { AppComponent } from './app.component';
import { routes } from './app.routes';

import { AboutModule } from './+about/about.module';
import { HomeModule } from './+home/home.module';
import {TestModule} from './+test/test.module';
import {VoteDataEntryModule} from './+vote-data-entry/vote-data-entry.module';
import { SharedModule } from './shared/shared.module';

@NgModule({
  imports: [BrowserModule, HttpModule, RouterModule.forRoot(routes), AboutModule, HomeModule,
    TestModule, VoteDataEntryModule, SharedModule.forRoot()],
  declarations: [AppComponent],
  providers: [{
    provide: APP_BASE_HREF,
    useValue: '<%= APP_BASE %>'
  }],
  bootstrap: [AppComponent]

})

export class AppModule { }

create-report-card-form.component.ts

import { Component, Input, Output, EventEmitter, OnInit} from '@angular/core';
import { FormBuilder, FormGroup, FormControl } from '@angular/forms';
// import { Dialog, Dropdown, SelectItem, Header, Footer, Messages, Message } from 'primeng/primeng';
import { SelectItem, Message } from 'primeng/primeng';

import {ReportCard, ReportCardDataSource} from '../shared/index';
import {CREATE_REPORT_CARD_FORM_HEADING, EDIT_REPORT_CARD_FORM_HEADING} from './constants';

@Component({
    moduleId: module.id,
    selector: 'create-report-card-form',
    templateUrl: 'create-report-card-form.component.html'
})
export class CreateReportCardFormComponent implements OnInit {

    @Input() public reportCardDataSourcesItems: SelectItem[];
    @Input() public reportCardYearItems: SelectItem[];
    @Input() errorMessages: Message[];

    @Output() reportCardCreated = new EventEmitter<ReportCard>();
    @Output() editReportCardFormValueChanged = new EventEmitter<ReportCard>();

    public editReportCardForm: FormGroup;
    private selectedReportCardDataSourceIdControl: FormControl;
    private selectedReportCardYearControl: FormControl;

    // TODO: remove this hack for resetting the angular 2 form once a real solution is available (supposedly in RC5)
    private isFormActive: boolean = true;
    private formHeaderString: string = CREATE_REPORT_CARD_FORM_HEADING;
    private formDialogVisible: boolean = false;
    private isCreatingNewReportCard = false;  // false implies that we are updating an existing report card

    constructor(private fb: FormBuilder) {
    }

    configureForm(selectedReportCard: ReportCard, createNewReport: boolean) {
        this.isCreatingNewReportCard = createNewReport;

        this.resetForm();

        this.selectedReportCardDataSourceIdControl.updateValue(selectedReportCard.reportCardDataSource.reportCardSourceId);

        this.selectedReportCardYearControl.updateValue(selectedReportCard.reportCardYear);

        if (createNewReport) {
            this.formHeaderString = CREATE_REPORT_CARD_FORM_HEADING;
        } else {
            // updating an existing report card
            this.formHeaderString = EDIT_REPORT_CARD_FORM_HEADING +
                selectedReportCard.reportCardYear + ' ' + selectedReportCard.reportCardDataSource.reportCardSourceName;
        }

        this.editReportCardForm.valueChanges.subscribe(data => this.onFormValueChanged(data));
    }

    customGroupValidator(reportCardDataSourceIdControl: FormControl, reportCardYearControl: FormControl,
        isCreatingNewReportCard: boolean) {
        return (group: FormGroup): { [key: string]: any } => {

            // missing data error ...
            if (!reportCardDataSourceIdControl.value || !reportCardYearControl.value) {
                return { 'requiredDataError': 'Report card year AND provider must be selected.' };
            }

            // invalid data error ...
            if (isCreatingNewReportCard) {
                if (!reportCardDataSourceIdControl.touched || !reportCardYearControl.touched) {
                    return { 'requiredDataError': 'Report card year AND provider must be selected.' };
                }
            } else {
                if (!reportCardDataSourceIdControl.touched && !reportCardYearControl.touched) {
                    return { 'requiredDataError': 'Report card year OR provider must be selected.' };
                }
            }

            // return null to indicate the form is valid
            return null;
        };
    }

    hideFormDialog() {
        this.formDialogVisible = false;
    }

    showFormDialog() {
        // hide any previous errors
        this.errorMessages = [];
        this.formDialogVisible = true;
    }

    createForm() {
        // by default, configure the form for new report card creation by setting
        // the initial values of both dropdowns to empty string
        this.selectedReportCardDataSourceIdControl = new FormControl('');
        this.selectedReportCardYearControl = new FormControl('');

        this.editReportCardForm = this.fb.group({
            selectedReportCardDataSourceIdControl: this.selectedReportCardDataSourceIdControl,
            selectedReportCardYearControl: this.selectedReportCardYearControl
        }, {
                validator: this.customGroupValidator(this.selectedReportCardDataSourceIdControl, this.selectedReportCardYearControl,
                    this.isCreatingNewReportCard),
                asyncValidator: this.duplicateReportCardValidator.bind(this)
            });
    }

    duplicateReportCardValidator() {
        return new Promise(resolve => {

            if ((this.errorMessages) && this.errorMessages.length === 0) {
                resolve({ uniqueReportCard: true });
            } else {
                resolve(null);
            }
        });
    }

    showError(errorMessages: Message[]) {
        this.errorMessages = errorMessages;
    }

    ngOnInit() {
        this.createForm();
    }

    onEditReportCardFormSubmitted() {

        let newReportCard = this.getReportCard(
            this.selectedReportCardDataSourceIdControl.value,
            this.selectedReportCardYearControl.value,
            this.reportCardDataSourcesItems
        );

        this.reportCardCreated.emit(newReportCard);
    }

    resetForm() {
        this.createForm();
        this.isFormActive = false;
        setTimeout(() => this.isFormActive = true, 0);
    }

    onFormValueChanged(data: any) {
        let newReportCard = this.getReportCard(
            this.selectedReportCardDataSourceIdControl.value,
            this.selectedReportCardYearControl.value,
            this.reportCardDataSourcesItems
        );

        this.editReportCardFormValueChanged.emit(newReportCard);
    }

    private getReportCard(reportCardDataSourceIdString: string, reportCardYearString: string,
        reportCardDataSourceItems: SelectItem[]): ReportCard {

        let selectedReportCardYear: number = Number(reportCardYearString);
        let selectedProviderReportCardId: number = Number(reportCardDataSourceIdString);

        let selectedProviderReportCardName: string = 'Unknown Report Card';

        for (var i = 0; i < this.reportCardDataSourcesItems.length; i++) {
            var element = this.reportCardDataSourcesItems[i];
            if (Number(element.value) === selectedProviderReportCardId) {
                selectedProviderReportCardName = element.label;
                break;
            }
        }

        let reportCard: ReportCard = new ReportCard();

        reportCard.reportCardYear = selectedReportCardYear;

        reportCard.reportCardDataSource = new ReportCardDataSource(
            selectedProviderReportCardId,
            selectedProviderReportCardName
        );

        return reportCard;
    }
}

create-report-card-form.component.html

<p-dialog header={{formHeaderString}} [(visible)]="formDialogVisible" [responsive]="true" showEffect="fade "
    [modal]="true" width="400">
    <form *ngIf="isFormActive" [formGroup]="editReportCardForm" (ngSubmit)="onEditReportCardFormSubmitted()">
        <div class="ui-grid ui-grid-responsive ui-fluid " *ngIf="reportCardDataSourcesItems ">
            <div class="ui-grid-row ">
                <p-dropdown [options]="reportCardDataSourcesItems" formControlName="selectedReportCardDataSourceIdControl" [autoWidth]="true"></p-dropdown>
            </div>
            <div class="ui-grid-row ">
                <p-dropdown [options]="reportCardYearItems" formControlName="selectedReportCardYearControl" [autoWidth]="true"></p-dropdown>
            </div>
            <div class="ui-grid-row ">
                <p-messages [value]="errorMessages"></p-messages>
            </div>
            <footer>
                <div class="ui-dialog-buttonpane ui-widget-content ui-helper-clearfix ">
                    <button type="submit" pButton icon="fa-check " 
                    [disabled]="!editReportCardForm?.valid" label="Save "></button>
                </div>
            </footer>
        </div>
    </form>
</p-dialog>

home.component.ts

import { Component, OnInit, ViewChild } from '@angular/core';
// // import { REACTIVE_FORM_DIRECTIVES } from '@angular/forms';
// import {ROUTER_DIRECTIVES} from '@angular/router';
// import { InputText, Panel, SelectItem, Message, Growl, Dialog, DataTable, Column, Header, Footer, Tooltip } from 'primeng/primeng';
import { Message, SelectItem } from 'primeng/primeng';

import {CreateReportCardFormComponent} from './create-report-card-form.component';
import { ReportCardDataSource, ReportCard, ProviderData, DataService,
   DUPLICATE_REPORT_CARD_MESSAGE } from '../shared/index';
import {ReportCardCommands} from './enums';

/**
 * This class represents the lazy loaded HomeComponent.
 */
@Component({
  moduleId: module.id,
  selector: 'sd-home',
  templateUrl: 'home.component.html',
  styleUrls: ['home.component.css']
  //,directives: [CreateReportCardFormComponent]
})

export class HomeComponent implements OnInit {

  public growlMessages: Message[] = [];
  public createReportCardError: Message[] = [];
  public reportCardDataSourcesItems: SelectItem[] = [{ label: 'Select Provider', value: '' }];
  public reportCardYearItems: SelectItem[] = [{ label: 'Select Year', value: '' }];
  public providerData: ProviderData = new ProviderData();
  public displayReportCardDeleteConfirmation: boolean = false;

  private isCreatingNewReportCard: boolean = true;
  private selectedReportCard: ReportCard;

  @ViewChild(CreateReportCardFormComponent)
  private createReportCardFormComponent: CreateReportCardFormComponent;

  constructor(private dataService: DataService) { }

  ngOnInit() {
    let reportCardDataSources: ReportCardDataSource[] = this.dataService.getReportCardDataSources();

    for (var i = 0; i < reportCardDataSources.length; i++) {
      var element = reportCardDataSources[i];
      this.reportCardDataSourcesItems.push({ label: element.reportCardSourceName, value: element.reportCardSourceId });

      // retrieve data from localStorage if available
      this.providerData = this.dataService.getProviderData();
    }

    // initialize report card years
    const minYear: number = 2000;
    // TODO: maxYear should be sourced from the server by a service
    let maxYear: number = (new Date()).getFullYear();

    for (var i = maxYear; i >= minYear; i--) {
      this.reportCardYearItems.push({ value: i.toString(), label: i.toString() });
    }
  }

  // Returns the index of the report card in providerData.reportCards that has the same reporCardSourceId
  // and reportCardYear as selectedReportCard, or -1 if there is no match.
  indexOf(selectedReportCard: ReportCard): number {
    return this.providerData.reportCards.findIndex(x =>
      x.reportCardDataSource.reportCardSourceId === selectedReportCard.reportCardDataSource.reportCardSourceId &&
      x.reportCardYear === selectedReportCard.reportCardYear);
  }

  onReportCardCreated(newReportCard: ReportCard) {
    if (newReportCard) {

      if ((this.indexOf(newReportCard) > -1)) {
        // attemp to create a duplicate report card; show error
        this.setCreateReportCardFromErrorMessage(DUPLICATE_REPORT_CARD_MESSAGE);
      } else {
        if (this.isCreatingNewReportCard) {
          // save new report card
          this.createReportCardError = [];
          this.createReportCardFormComponent.hideFormDialog();
          this.providerData.reportCards.splice(0, 0, newReportCard);

          this.createReportCardFormComponent.hideFormDialog();

        } else {
          // update existing report card
          let reportCardToUpdateIndex: number = this.indexOf(this.selectedReportCard);

          if (reportCardToUpdateIndex > -1) {
            this.providerData.reportCards[reportCardToUpdateIndex].reportCardDataSource.reportCardSourceId
              = newReportCard.reportCardDataSource.reportCardSourceId;
            this.providerData.reportCards[reportCardToUpdateIndex].reportCardDataSource.reportCardSourceName
              = newReportCard.reportCardDataSource.reportCardSourceName;
            this.providerData.reportCards[reportCardToUpdateIndex].reportCardYear
              = newReportCard.reportCardYear;
          }
        }
        this.dataService.storeProviderData(this.providerData);
        this.isCreatingNewReportCard = true;
        this.clearCreateReportCardFormErrorMessage();
        this.createReportCardFormComponent.hideFormDialog();
      }
    }
  }

  editReportCardFormValueChanged(newReportCard: ReportCard) {
    if (this.indexOf(newReportCard) === -1) {
      // clear duplicate report card error message in 'create report card' dialog
      this.clearCreateReportCardFormErrorMessage();
    } else {
      // set duplicate report card error message
      this.setCreateReportCardFromErrorMessage(DUPLICATE_REPORT_CARD_MESSAGE);
    }
  }

  onAddReportCardButtonClicked() {
    this.isCreatingNewReportCard = true;
    this.createReportCardFormComponent.configureForm(new ReportCard(), this.isCreatingNewReportCard);
    this.createReportCardFormComponent.showFormDialog();
  }

  onReportCardDeleteButtonClicked(reportCard: ReportCard) {
    this.reportCardCommandExecute(reportCard, ReportCardCommands.Delete);
  }

  onReportCardEditButtonClicked(reportCard: ReportCard) {
    this.reportCardCommandExecute(reportCard, ReportCardCommands.EditReportCard);
  }

  onAddVotesRouterLinkClicked(reportCard: ReportCard) {
    this.reportCardCommandExecute(reportCard, ReportCardCommands.EditVotes);
  }

  onReportCardDeleteConfirmButtonClick(isDeleteOk: boolean) {
    if (isDeleteOk) {
      this.providerData.reportCards.splice(this.providerData.selectedReportCardIndex, 1);
      // store updated reportCards in local storage
      this.dataService.storeProviderData(this.providerData);
    }
    this.displayReportCardDeleteConfirmation = false;
  }

  reportCardCommandExecute(reportCard: ReportCard, command: ReportCardCommands) {
    this.providerData.selectedReportCardIndex = this.indexOf(reportCard);
    this.selectedReportCard = reportCard;

    switch (command) {
      case ReportCardCommands.EditVotes:
        this.dataService.storeProviderData(this.providerData);
        break;
      case ReportCardCommands.Delete:
        this.displayReportCardDeleteConfirmation = true;
        break;
      case ReportCardCommands.EditReportCard:
        this.isCreatingNewReportCard = false;
        this.createReportCardFormComponent.configureForm(reportCard, this.isCreatingNewReportCard);
        this.createReportCardFormComponent.showFormDialog();
        break;
      default:
        break;
    }
  }

  private setCreateReportCardFromErrorMessage(message: Message) {
    this.createReportCardError = [];
    this.createReportCardError.push(message);

    this.createReportCardFormComponent.showError(this.createReportCardError);
  }

  private clearCreateReportCardFormErrorMessage() {
    this.createReportCardError = [];
    this.createReportCardFormComponent.showError(this.createReportCardError);
  }
}

home.component.html

<p-growl [value]="growlMessages" sticky="sticky"></p-growl>
<p-dataTable [value]="providerData.reportCards" [paginator]="true" rows="15" [responsive]="true">
  <header>
    <div>
      <h1>Report Cards ({{providerData.reportCards.length}})</h1>
    </div>
    <button type="button" pButton icon="fa-plus" (click)="onAddReportCardButtonClicked()" label="Add" title="Add new report card"></button>
  </header>
  <p-column styleClass="col-button">
    <template let-reportCard="rowData">
      <button type="button" pButton (click)="onReportCardEditButtonClicked(reportCard)" icon="fa-pencil" title="Edit report card"></button>
    </template>
  </p-column>
  <p-column field="reportCardDataSource.reportCardSourceName" header="Report Card" [sortable]="true"></p-column>
  <p-column field="reportCardYear" header="Year" [sortable]="true"></p-column>
  <p-column header="Votes" [sortable]="false">
    <template let-reportCard="rowData">
      {{reportCard.votes.length}}
      <!--<button type="button" pButton icon="fa-pencil-square" (click)="editVotes(reportCard)" title="Edit votes"></button>-->
      <a [routerLink]="['/votes']" (click)="onAddVotesRouterLinkClicked(reportCard)">Edit</a>
    </template>
  </p-column>
  <p-column styleClass="col-button">
    <template let-reportCard="rowData">
      <button type="button" pButton (click)="onReportCardDeleteButtonClicked(reportCard)" icon="fa-trash" title="Delete report card"></button>
    </template>
  </p-column>
</p-dataTable>

<create-report-card-form [currentReportCardCount]="providerData.reportCards.length" [reportCardDataSourcesItems]="reportCardDataSourcesItems"
  [reportCardYearItems]="reportCardYearItems" (reportCardCreated)=onReportCardCreated($event) (editReportCardFormValueChanged)=editReportCardFormValueChanged($event)>
</create-report-card-form>

<p-dialog header="Confirm Deletion" [(visible)]="displayReportCardDeleteConfirmation" modal="modal" showEffect="fade">
  <p>
    Delete the following report card and all related data (<strong>NO undo</strong>)?
  </p>
  <p>
    <strong>{{providerData?.reportCards[providerData.selectedReportCardIndex]?.reportCardDataSource?.reportCardSourceName}}</strong><br/>
    <strong>{{providerData?.reportCards[providerData.selectedReportCardIndex]?.reportCardYear}}</strong>
  </p>
  <footer>
    <div class="ui-dialog-buttonpane ui-widget-content ui-helper-clearfix">
      <button type="button" pButton icon="fa-close" (click)="onReportCardDeleteConfirmButtonClick(false)" label="No"></button>
      <button type="button" pButton icon="fa-check" (click)="onReportCardDeleteConfirmButtonClick(true)" label="Yes"></button>
    </div>
  </footer>
</p-dialog>
You should include the code from create-report-card-form.component.ts
@Isaac - added the code from create-report-card-form.component.ts
Can you post the templates, as well? The error is telling you that either the create-report-card-form template or the parent component is trying to bind to or access a 'currentReportCardCount' property which doesn't appear to exist on the CreateReportCardFormComponent component.
@AndrewBabin - added code and template for parent and child component.

A
ABabin
<create-report-card-form [currentReportCardCount]="providerData.reportCards.length" ...
                         ^^^^^^^^^^^^^^^^^^^^^^^^

In your HomeComponent template, you are trying to bind to an input on the CreateReportCardForm component that doesn't exist.

In CreateReportCardForm, these are your only three inputs:

@Input() public reportCardDataSourcesItems: SelectItem[];
@Input() public reportCardYearItems: SelectItem[];
@Input() errorMessages: Message[];

Add one for currentReportCardCount and you should be good to go.


Thanks! Adding an @Input() for currentReportCardCount fixed this problem. My mistake was to assume the code was correct just because it worked in RC4 and before.
Also, if your component is an a shared Module. Make sure you add it to the both the @NgModule declaration AND exports arrays.
@ABabin I have same issue but for more info you can check it here : stackoverflow.com/questions/66429902/… I was wondering if someone can help me there..
H
Houman

I fixed it with adding the prefix (attr.) :

<create-report-card-form [attr.currentReportCardCount]="expression" ...

Unfortunately this haven't documented properly yet.

more detail here


Don't do this. It will stop that property from being passed down to nested directives.
@igasparetto in a situation like this, you probably don't have directives nested inside
I had the same issue when adding a non-standard attribute to a button tag and I could solve it by doing this. Thank you.
C
Caner

There are multiple possible causes for this error:

1) When you put the property 'x' inside brackets you are trying to bind to it. Therefore first thing to check is if the property 'x' is defined in your component with an Input() decorator

Your html file:

<body [x]="...">

Your class file:

export class YourComponentClass {

  @Input()
  x: string;
  ...
}

(make sure you also have the parentheses)

2) Make sure you registered your component/directive/pipe classes in NgModule:

@NgModule({
  ...
  declarations: [
    ...,
    YourComponentClass
  ],
  ...
})

See https://angular.io/guide/ngmodule#declare-directives for more details about declare directives.

3) Also happens if you have a typo in your angular directive. For example:

<div *ngif="...">
     ^^^^^

Instead of:

<div *ngIf="...">

This happens because under the hood angular converts the asterisk syntax to:

<div [ngIf]="...">

Life saver. I couldn't get that error message.. Problem was I did not registered my child component in module.
Another reason why this error could happen is when you want to use attribute selectors for your component but forget the brackets in the selector. Example: you want to do this:<tr my-component></tr> but in the @Component you do this selector: 'my-component' instead of selector: '[my-component]'...
Yes - that error message can be misleading - I upvoted this answer since it more thoroughly answers this question in the general case. Specifically #2 is not intuitive at all based on the error "Can't bind to 'Property X' since it isn't a known property of 'Child Component'" - so this is a helpful tip to track that down.
A
Alf Moh

If you use the Angular CLI to create your components, let's say CarComponent, it attaches app to the selector name (i.e app-car) and this throws the above error when you reference the component in the parent view. Therefore you either have to change the selector name in the parent view to let's say <app-car></app-car> or change the selector in the CarComponent to selector: 'car'


Funny it's the small things that bite you the hardest
I searched the answer to this question for a long time! You simply solved the issue! It works fine! Thank you!
p
peterh

I ran into the same error, when I just forgot to declare my custom component in my NgModule - check there, if the others solutions won't work for you.


r
raj lanjewar
*Parent component:*
step 1:
-app.component.ts (parent class file)
export class AppComponent {
  name = "Bruce Waine";
}
-app.component.html (parent template file)
<app-child [data]="name"></app-child>   /*<app-child> is child component selector*/

*Child Component:*
step 2:child.component.ts(child component class file)
--parent input
import { Component, OnInit, Input } from '@angular/core';
export class ChildComponent implements OnInit {
  **@Input() data: any;**

  constructor() { }

  ngOnInit(): void {
  }

}

-child.component.html(child component template file)
<p>{{data}}</p>