javascript - Angular 4 pass data between 2 not related components

Question

I have a questions about passing data in Angular.

First, I don't have a structure as <parent><child [data]=parent.data></child></parent>

My structure is

<container>
  <navbar>
    <summary></summary>
    <child-summary><child-summary>
  </navbar>
  <content></content>
</container>

So, in <summary /> I have a select that do send value to <child-summary /> and <content />.

OnSelect method is well fired with (change) inside <summary /> component.

So, I tried with @Input, @Output and @EventEmitter directives, but I don't see how retrieve the event as @Input of the component, unless to go on parent/child pattern. All examples I've founded has a relation between component.

EDIT : Example with BehaviorSubject not working (all connected service to API works well, only observable is fired at start but not when select has value changed)

shared service = company.service.ts (used to retrieve company data)

import { Injectable } from '@angular/core';
import { Headers, Http, Response } from '@angular/http';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';

import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/toPromise';

@Injectable()
export class SrvCompany {

    private accountsNumber = new BehaviorSubject<string[]>([]);
    currentAccountsNumber = this.accountsNumber.asObservable();

    changeMessage(accountsNumber: string[]) {
        this.accountsNumber.next(accountsNumber);
    }

    private _companyUrl = 'api/tiers/';

    constructor(private http: Http) { }

    getSociete(): Promise<Response> {
        let url = this._companyUrl;
        return this.http.get(url).toPromise();
    }
}

invoice.component.ts (the "child")

import { Component, OnInit, Input } from '@angular/core';
import { Headers, Http, Response } from '@angular/http';

import { SrvInvoice } from './invoice.service';
import { SrvCompany } from '../company/company.service';

@Component({
    selector: 'invoice',
    templateUrl: 'tsScripts/invoice/invoice.html',
    providers: [SrvInvoice, SrvCompany]
})

export class InvoiceComponent implements OnInit  {

    invoice: any;

    constructor(private srvInvoice: SrvInvoice, private srvCompany: SrvCompany)
    {

    }

    ngOnInit(): void {
        //this.getInvoice("F001");

        // Invoice data is linked to accounts number from company.
        this.srvCompany.currentAccountsNumber.subscribe(accountsNumber => {
            console.log(accountsNumber);
            if (accountsNumber.length > 0) {
                this.srvInvoice.getInvoice(accountsNumber).then(data => this.invoice = data.json());
            }
        });
    }

    //getInvoice(id: any) {
    //    this.srvInvoice.getInvoice(id).then(data => this.invoice = data.json());
    //}
}

company.component.ts (the trigerring "parent")

import { Component, Inject, OnInit, Input } from '@angular/core';
import { Headers, Http, Response } from '@angular/http';

import { SrvCompany } from './company.service';

@Component({
    selector: 'company',
    templateUrl: 'tsScripts/company/company.html',
    providers: [SrvCompany]    
})

export class CompanyComponent implements OnInit {

    societes: any[];    
    soc: Response[]; // debug purpose
    selectedSociete: any;

    ville: any;
    ref: any;
    cp: any;
    accountNumber: any[];

    constructor(private srvSociete: SrvCompany)
    {

    }

    ngOnInit(): void {
        this.getSocietes();
    }

    getSocietes(): void {

        this.srvSociete.getSociete()
            .then(data => this.societes = data.json())
            .then(data => this.selectItem(this.societes[0].Id));
    }

    selectItem(value: any) {
        this.selectedSociete = this.societes.filter((item: any) => item.Id === value)[0];
        this.cp = this.selectedSociete.CodePostal;
        this.ville = this.selectedSociete.Ville;
        this.ref = this.selectedSociete.Id;
        this.accountNumber = this.selectedSociete.Accounts;
        console.log(this.accountNumber);
        this.srvSociete.changeMessage(this.accountNumber);
    }
}

question from:https://stackoverflow.com/questions/44414226/angular-4-pass-data-between-2-not-related-components

Answer 1

This is a case where you want to use a shared service, as your components are structured as siblings and grandchildren. Here's an example from a video I created a video about sharing data between components that solves this exact problem.

Start by creating a BehaviorSubject in the service

import { Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
@Injectable()
export class DataService {

  private messageSource = new BehaviorSubject("default message");
  currentMessage = this.messageSource.asObservable();

  constructor() { }

  changeMessage(message: string) {
    this.messageSource.next(message)
  }

}

Then inject this service into each component and subscribe to the observable.

import { Component, OnInit } from '@angular/core';
import { DataService } from "../data.service";
@Component({
  selector: 'app-parent',
  template: `
    {{message}}
  `,
  styleUrls: ['./sibling.component.css']
})
export class ParentComponent implements OnInit {

  message:string;

  constructor(private data: DataService) { }

  ngOnInit() {
    this.data.currentMessage.subscribe(message => this.message = message)
  }

}

You can change the value from either component and the value will be updated, even if you don't have the parent/child relationship.

import { Component, OnInit } from '@angular/core';
import { DataService } from "../data.service";
@Component({
  selector: 'app-sibling',
  template: `
    {{message}}
    <button (click)="newMessage()">New Message</button>
  `,
  styleUrls: ['./sibling.component.css']
})
export class SiblingComponent implements OnInit {

  message:string;

  constructor(private data: DataService) { }

  ngOnInit() {
    this.data.currentMessage.subscribe(message => this.message = message)
  }

  newMessage() {
    this.data.changeMessage("Hello from Sibling")
  }

}