I'm trying to load an array of objects from a JSON and display them in my template with *ngFor in my angular2 app. I'm getting this error Cannot find a differ supporting object '[object Object]' of type 'object'. NgFor only supports binding to Iterables such as Arrays..
I've found quite a bit of documentation on this particular error and a fix, but I'm having trouble understanding/translating it into a working fix. From what I understand the *ngFor will only render arrays of data and my home.component is trying to render an object of arrays.
The fix I've read is to write a pipe like this:
#Pipe({ name: 'values', pure: false })
export class ValuesPipe implements PipeTransform {
transform(value: any, args: any[] = null): any {
return Object.keys(value).map(key => value[key]);
}
}
I've tried this but then I'm getting an error that says compiler.umd.js?9df7:14126Uncaught Error: Unexpected value 'HomeComponent' declared by the module 'AppModule' I've built the pipe directly into my home component so I'm unsure why this is a problem.
Here is my code.
home.component.js
import { Component, OnInit, Pipe, PipeTransform } from '#angular/core';
import { Project } from './project';
import { ProjectService } from './project.service';
#Component({
selector: 'home',
templateUrl: './home.html',
styleUrls: ['./home.scss'],
providers: [ProjectService]
})
#Pipe({ name: 'values', pure: false })
export class ValuesPipe implements PipeTransform {
transform(value: any, args: any[] = null): any {
return Object.keys(value).map(key => value[key]);
}
}
export class HomeComponent implements OnInit {
errorMessage: string;
projects: Project[];
selectedProject: Project;
mode = 'Observable';
constructor(private projectService: ProjectService) { }
ngOnInit() { this.getProjects(); }
getProjects() {
this.projectService.getProjects()
.subscribe(
projects => this.projects = projects,
error => this.errorMessage = <any>error);
}
onSelect(project: Project): void {
this.selectedProject = project;
}
}
projects.service.js
import { Injectable } from '#angular/core';
import { Http, Response } from '#angular/http';
import { Project } from './project';
import { Observable } from 'rxjs/Observable';
#Injectable()
export class ProjectService {
private projectsUrl = 'data/project.json'; // URL to web API
constructor(private http: Http) { }
getProjects(): Observable<Project[]> {
return this.http.get(this.projectsUrl)
.map(this.extractData)
.catch(this.handleError);
}
private extractData(res: Response) {
let body = res.json();
return body.data || {};
}
private handleError(error: Response | any) {
// In a real world app, we might use a remote logging infrastructure
let errMsg: string;
if (error instanceof Response) {
const body = error.json() || '';
const err = body.error || JSON.stringify(body);
errMsg = `${error.status} - ${error.statusText || ''} ${err}`;
} else {
errMsg = error.message ? error.message : error.toString();
}
console.error(errMsg);
return Observable.throw(errMsg);
}
}
project.json
{
"project": [{
"title": "The Upper Crust",
"id": "upper-crust",
"year": "2016",
"category": ["Design", "Web Design"],
"thumbnail": "thumbnails/upper-crust.jpg"
}, (...)
}
Sorry if the answer is already out there I've spent a few hours last night and this morning trying to solve this issue and can't seem to figure it out. I appreciate your help in advance, I'm new to development and am at a loss with much of this stuff.
Related
I'm learning to code and just ran into this issue with Angular 6 which I can't seem to solve. I was able to get JSON's data before but now that it's nested I don't know how to get it's data. This is what I've done so far
Service
import { Injectable } from '#angular/core';
import { Http, Response } from '#angular/http';
import { Observable } from 'rxjs';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/toPromise';
#Injectable()
export class TestService {
url = "http://localhost:80/assets/data/test.json";
constructor(private http:Http) { }
getTestWithObservable(): Observable<any> {
return this.http.get(this.url)
.map(this.extractData)
.catch(this.handleErrorObservable);
}
private extractData(res: Response) {
let body = res.json();
return body;
}
private handleErrorObservable (error: Response | any) {
console.error(error.message || error);
return Observable.throw(error.message || error);
}
}
Component
import { Component, OnInit } from '#angular/core';
import { Observable } from 'rxjs';
import { TestService } from './test.service';
#Component({
selector: 'ngx-test',
styleUrls: ['./test.component.scss'],
templateUrl: './test.component.html',
})
export class TestComponent implements OnInit {
observableTest: Observable<any>
errorMessage: String;
constructor(private testService: TestService) { }
ngOnInit(): void {
this.testService.getTestWithObservable().subscribe(
res => {
let user = res[0]["users"];
let user_data = user["data"];
console.log(user_data["name"]);
}
);
}
}
JSON
[{
"id": 1,
"users": {
"user_id": 14,
"data": [{
"name": "James",
"age": 20
},
{
"name": "Damien",
"age": 25
}]
}
}]
HTML
<div *ngFor="let x of user_data; let i = index">
{{x.name}}
</div>
I'd appreciate if someone can point me out the solution or what I'm doing wrong.
You need to save the data in an instance property to access it. user_data is local to your function, you cannot access it in the template so you should use something like this :
export class TestComponent implements OnInit {
observableTest: Observable<any>
errorMessage: String;
user_data: any;
constructor(private testService: TestService) { }
ngOnInit(): void {
this.testService.getTestWithObservable().subscribe(
res => {
let user = res[0]['users'];
let user_data = user['data'];
console.log(user_data['name']);
this.user_data = user_data; // here
}
);
}
}
There is some problems with your code:
export class TestComponent implements OnInit {
observableTest: Observable<any>
errorMessage: String;
user_data: any;
constructor(private testService: TestService) {
}
ngOnInit(): void {
this.testService.getTestWithObservable().subscribe(
res => {
let user = res[0]["users"];
this.user_data = user["data"];
console.log(user_data["name"]);
}
);
}
}
In Angular >= 4, pipe methods is better to handle Observable
this.http.get(this.url)
.pipe(
filter(...),
map(...)
)
With HttpClient (Http is deprecated), the .json() is done for you. You don't need your extractData function.
You have to initialize your variable. And use "this" to refer to it.
I am developing the services of my application, but when I try to load the page it shows the following error:
Can't resolve all parameters for GameEditComponent: ([object Object],
[object Object], ?).
I tried in the service to put as an array or just leave any, but even then the error continued
game-edit.service.ts
import { Injectable } from '#angular/core';
import { Http } from '#angular/http';
import { Observable } from 'rxjs';
#Injectable()
export class GameEditService {
constructor(private http: Http) { }
getGame(id): Observable<any> {
return this.http.get('http://localhost:8080/lightning/api/game' + id).map(res => res.json()).catch(error => {
throw new Error(error.message);
});
}
getManufactures(): Observable<any> {
return this.http.get('http://localhost:8080/lightning/api/manufacture').map(res => res.json()).catch(error => {
throw new Error(error.message);
});
}
getPlatforms(): Observable<any> {
return this.http.get('http://localhost:8080/lightning/api/platform').map(res => res.json()).catch(error => {
throw new Error(error.message);
});
}
}
game-edit.component.ts
import { ActivatedRoute, Params } from '#angular/router';
import { Component, OnInit } from '#angular/core';
import { GameEditService } from './game-edit.service';
#Component({
moduleId: module.id,
selector: 'app-game-edit',
templateUrl: './game-edit.component.html',
styleUrls: ['./game-edit.component.css', '../styles.css' ]
})
export class GameEditComponent implements OnInit {
constructor(private activatedRoute: ActivatedRoute, private gameEditService: GameEditService, private id) {
this.gameEditService.getPlatforms().subscribe(platforms => {
console.log(platforms);
}), erro => console.log(erro);
this.gameEditService.getManufactures().subscribe(manufactures => {
console.log(manufactures);
}), erro => console.log(erro);
}
ngOnInit() {
this.activatedRoute.params.subscribe((params: Params) => {
this.id = params['id'];
console.log(this.id);
});
this.gameEditService.getGame(this.id).subscribe(game => {
console.log(game);
}), erro => console.log(erro);
}
onSubmit(form){
console.log(form);
}
verificaValidTouched(campo){
return !campo.valid && campo.touched;
}
aplicaCssErro(campo){
return {
'subError': this.verificaValidTouched(campo)
}
}
}
This is the json that is coming, the first is for a selected game, the second is for the platforms and the third is for the manufacturers
json game selected
{
"id":1,
"name":"Street Fighter",
"category":"luta",
"price":20.5,
"quantity":1000,
"production":true,
"description":"descricao",
"image":"ps4.jpg",
"manufacture":
{
"id":1,
"name":"Sony",
"image":"ps4.jpg",
"imageFullPath":"http://localhost:8080/lightning/images/ps4.jpg"
}
}
json platforms
{
"id":1,
"name":"PC",
"image":"ps4.jpg",
"imageFullPath":"http://localhost:8080/lightning/images/ps4.jpg"
}
json manufactures
{
"id":1,
"name":"Sony",
"image":"ps4.jpg",
"imageFullPath":"http://localhost:8080/lightning/images/ps4.jpg"
}
Console
I'm using angular cli with with all packages in the most current versions.
I do not know if maybe this error is because of the platforms you have inside the game, or some other code problem, if you know something that could do to repair, I tried several solutions that I found through the internet, but none worked.
Thanks in advance.
The problem is the last argument in the component's constructor, private id. Angular will try to resolve this dependency, but can't find an injectable class for id. When looking at the code, I think there is no need to inject id into the constructor. Just define it as a property on your component:
// ... import statements
#Component({
moduleId: module.id,
selector: 'app-game-edit',
templateUrl: './game-edit.component.html',
styleUrls: ['./game-edit.component.css', '../styles.css' ]
})
export class GameEditComponent implements OnInit {
private id; // put the declaration of id here
// remove id declaration from the constructor, no need to inject it
constructor(private activatedRoute: ActivatedRoute,
private gameEditService: GameEditService) { // ...constructor code}
// other code
}
I solved it otherwise: My problem was that the HttpClient has a rare condition, it's not the same "import" line on the component that on the app.module...
On the Component is this:
import { HttpClient } from '#angular/common/http';
in app module is this:
import { HttpClientModule } from '#angular/common/http';
I've created an angular app which gets data from a json file. But I'm having issues with showing the data in html. A lot of variables are in dutch, I'm sorry for that. I'm also a bit new to all of this :)
This is my service:
import {Injectable} from '#angular/core';
import {Http, RequestOptions, Response, Headers} from '#angular/http';
import {Observable} from "rxjs";
import {Afdelingen} from "./models";
#Injectable()
export class AfdelingService {
private afdelingenUrl = '/assets/backend/afdelingen.json';
constructor(private http: Http) {
}
getAfdelingen(): Observable<Afdelingen[]> {
return this.http.get(this.afdelingenUrl)
.map(this.extractData)
.catch(this.handleError);
}
private extractData(res: Response) {
let body = <Afdelingen[]>res.json();
return body || {};
}
private handleError(error: any): Promise<any> {
console.error('An error occurred', error);
return Promise.reject(error.message || error);
}
addAfdeling(afdelingsNaam: string, afdeling: any): Observable<Afdelingen> {
let body = JSON.stringify({"afdelingsNaam": afdelingsNaam, afdeling: afdeling});
let headers = new Headers({'Content-Type': 'application/json'});
let options = new RequestOptions({headers: headers});
return this.http.post(this.afdelingenUrl, body, options)
.map(res => <Afdelingen> res.json())
.catch(this.handleError)
}
}
This is part of my json file:
{
"afdelingen": [
{
"afdelingsNaam": "pediatrie",
"kamernummer": 3.054,
"patientid": 10001,
"patientennaam": "Joske Vermeulen",
"reden": "Appendicitis",
"opname": "12/05/2017",
"ontslag": "28/06/2017",
"behandelingstype": "nazorg",
"behandelingsomschrijving": "wondverzorging",
"behandelingsdatum": "10/06/2017",
"behandelingstijd": "10:20",
"vegitarisch": false,
"Opmerkingen": "",
"sanitair": true,
"kinderverzorgingsruimte": false,
"salon": true,
"hulp": true,
"width": 5,
"height": 5
},
{
"afdelingsNaam": "pediatrie",
"kamernummer": 3.055,
"patientid": 10002,
"patientennaam": "Agnes Vermeiren",
"reden": "Beenbreuk",
"opname": "18/05/2017",
"ontslag": "30/06/2017",
"behandelingstype": "nazorg",
"behandelingsomschrijving": "wondverzorging",
"behandelingsdatum": "10/06/2017",
"behandelingstijd": "10:20",
"vegitarisch": true,
"Opmerkingen": "",
"sanitair": true,
"kinderverzorgingsruimte": false,
"salon": true,
"hulp": false,
"width": 5,
"height": 5
}]}
The Component:
import {Component, OnInit, Input} from '#angular/core';
import {Afdelingen} from "../models";
import {AfdelingService} from "../afdeling.service";
import {PatientService} from "../patient.service";
#Component({
selector: 'app-afdeling',
templateUrl: './afdeling.component.html',
styleUrls: ['./afdeling.component.css']
})
export class AfdelingComponent implements OnInit {
afdeling: Afdelingen[];
errorMessage:string;
constructor(private afdelingService: AfdelingService, private patientService: PatientService) { }
ngOnInit() {
this.getData()
}
getData() {
this.afdelingService.getAfdelingen()
.subscribe(
data => {
this.afdeling = data;
console.log(this.afdeling);
}, error => this.errorMessage = <any> error);
}
}
and the html:
<ul>
<li *ngFor="let afd of afdeling">
{{afd.patientid}}
</li>
</ul>
As the error messages stated, ngFor only supports Iterables such as Array, so you cannot use it for Object.
change
private extractData(res: Response) {
let body = <Afdelingen[]>res.json();
return body || {}; // here you are return an object
}
to
private extractData(res: Response) {
let body = <Afdelingen[]>res.json().afdelingen; // return array from json file
return body || []; // also return empty array if there is no data
}
Remember to pipe Observables to async, like *ngFor item of items$ | async, where you are trying to *ngFor item of items$ where items$ is obviously an Observable because you notated it with the $ similar to items$: Observable<IValuePair>, and your assignment may be something like this.items$ = this.someDataService.someMethod<IValuePair>() which returns an Observable of type T.
Adding to this... I believe I have used notation like *ngFor item of (items$ | async)?.someProperty
You only need the async pipe:
<li *ngFor="let afd of afdeling | async">
{{afd.patientid}}
</li>
always use the async pipe when dealing with Observables directly without explicitly unsubscribe.
I was the same problem and as Pengyy suggest, that is the fix. Thanks a lot.
My problem on the Browser Console:
PortafolioComponent.html:3 ERROR Error: Error trying to diff '[object
Object]'. Only arrays and iterables are allowed(…)
In my case my code fix was:
//productos.service.ts
import { Injectable } from '#angular/core';
import { Http } from '#angular/http';
#Injectable()
export class ProductosService {
productos:any[] = [];
cargando:boolean = true;
constructor( private http:Http) {
this.cargar_productos();
}
public cargar_productos(){
this.cargando = true;
this.http.get('https://webpage-88888a1.firebaseio.com/productos.json')
.subscribe( res => {
console.log(res.json());
this.cargando = false;
this.productos = res.json().productos; // Before this.productos = res.json();
});
}
}
I need to generate sanitized css property to use with my component template to set the background image of the div:
<div *ngFor="let Item of Items"
[style.background-image]="Item.imageStyle
(click)="gotoDetail(Item.iditems)">
</div>
using data obtained through a data service. The component is:
import { Component } from '#angular/core';
import { Router } from '#angular/router';
import { DomSanitizer } from '#angular/platform-browser';
import { OnInit } from '#angular/core';
import { Item } from '../models/Item';
import { CollectionDataService } from '../services/CollectionData.service';
#Component({
selector: 'mainpage',
templateUrl: 'app/mainpage/mainpage.component.html',
styleUrls: ['app/mainpage/mainpage.component.css']
})
export class MainpageComponent implements OnInit {
Items: Item[];
ngOnInit() {
this.collectionDataService.getItems().subscribe(
Items => this.Items = Items
);
// Generates and sanitizes image links
this.Items.map(
(LItem) => LItem.imageStyle = this.sanitizer.bypassSecurityTrustStyle("url(template/images/"+LItem.iditems+".jpg)")
)
}
constructor(
private router: Router,
private sanitizer: DomSanitizer,
private collectionDataService: CollectionDataService
) {
}
gotoDetail($iditems: number): void {
this.router.navigate(['/viewer', $iditems]);
}
}
But it doesn't work because the statement that generates the sanitized property
this.Items.map(
(LItem) => LItem.imageStyle = this.sanitizer.bypassSecurityTrustStyle("url(template/images/"+LItem.iditems+".jpg)")
)
doesn't find the loaded data. The error that I'm seeing in the browser console is:
core.umd.js:3070 EXCEPTION: Uncaught (in promise): Error: Error in ./MainpageComponent class MainpageComponent_Host - inline template:0:0 caused by: Cannot read property 'map' of undefined
TypeError: Cannot read property 'map' of undefined
The data service is:
import { Injectable } from '#angular/core'
import { Http } from '#angular/http'
import { Item } from '../models/Item';
import { DomSanitizer } from '#angular/platform-browser';
#Injectable()
export class CollectionDataService {
constructor(
private http: Http,
private sanitizer: DomSanitizer
) { }
getItems() {
return this.http.get('app/mocksdata/items.json').map(
response => <Item[]>response.json().items
)
}
}
And the provided items.json:
{
"items": [{
"iditems": 1,
"imageStyle": ""
}, {
"iditems": 2,
"imageStyle": ""
}]
}
If I set static data in the component, instead of using the data service, everything works:
export class MainpageComponent implements OnInit {
Items: Item[];
ngOnInit() {
this.Items = [{
"iditems": 1,
"imageStyle": ""
}, {
"iditems": 2,
"imageStyle": ""
}]
// Generates and sanitizes image links
this.Items.map(
(LItem) => LItem.imageStyle = this.sanitizer.bypassSecurityTrustStyle("url(template/images/"+LItem.iditems+".jpg)")
)
}
How can I force the sanitizer statement to wait that the async data are fully loaded? Alternatively how can I generate sanitized properties directly in the service?
EDIT
The best answer comes from PatrickJane below:
Items: Item[] = [];
ngOnInit() {
this.collectionDataService.getItems().subscribe(Items => {
this.Items = Items;
this.Items.map(LItem => LItem.imageStyle = this.sanitizer.bypassSecurityTrustStyle("url(template/images/"+LItem.iditems+".jpg)"))}
});
}
I also solved this problem working directly in the service method (credits), but it is more verbose:
return this.http.get('app/mocksdata/items.json')
.map( (responseData) => {
return responseData.json().items;
})
.map(
(iitems: Array<any>) => {
let result:Array<Item> = [];
if (iitems) {
iitems.forEach((iitem) => {
iitem.imageStyle = this.sanitizer.bypassSecurityTrustStyle("url(template/images/"+iitem.iditems+".jpg)");
result.push(<Item>iitem);
});
}
return result;
}
)
The subscribe function is async so your map function called before the subscribe function run. So in this phase the array is undefined because you doesn't set any initial value.
The solution is to do this inside the subscribe function and to initialize the Items with empty array.
Items: Item[] = [];
ngOnInit() {
this.collectionDataService.getItems().subscribe(Items => {
this.Items = Items;
this.Items.map(LItem => LItem.imageStyle = this.sanitizer.bypassSecurityTrustStyle("url(template/images/"+LItem.iditems+".jpg)"))}
});
}
I'm struggling to do a http get request with Angular 2. I've made a file with the JSON information that I want to "get" with my TeacherInfo class and use it to display information by the account component which is used in a routing.
If I click in the routerLink for this element nothing is displayed and if I switch to another routerLink there is neither ( there was before, all routerLinks worked just fine )
file: TeacherInfo.service.ts
import {Injectable, OnInit} from '#angular/core';
import { Http, Response , Headers} from '#angular/http';
import { account } from '../components/account.component';
import {Observable} from "rxjs";
#Injectable()
export class TeacherInfo {
constructor ( private http : Http) {}
private url = '../test.json';
getInfo(){
return this.http.get(this.url)
.toPromise()
.then(response => response.json().data as account );
}
}
file: account.component.ts
import {Component, OnInit} from '#angular/core';
import { TeacherInfo } from '../services/TecherInfo.service';
#Component({
template:`
<h2>This is not ready jet!</h2>
<p>
Willkommen {{name}}! <br/>
E-mail: {{email}}<br/>
</p>
`
})
export class account implements OnInit{
public id : number;
public name : string;
public email: string;
private acc : account;
constructor(private accountinfoservice : TeacherInfo) {
}
getInfo() {
this.accountinfoservice.getInfo()
.then(( info : account ) => this.acc = info );
}
ngOnInit () {
this.getInfo();
if ( this.acc != null ) {
this.id = this.acc.id;
this.name = this.acc.name;
this.email = this.acc.email;
}else {
console.log("there is no data! ");
}
}
and finally test.json :
{
"id" : "1",
"name": "testname",
"email": "testemail"
}
I'm using the latest versions of node and npm and I get no compilation errors and just unrelated errors in the browser console ( other SPA's parts which aren't ready yet). The observable implementations are there because at first I tried to do it that way and came to the conclusion it's easier at first to use a promise.
I subscribe for simple json gets
Calling code
ngOnInit(): void {
this._officerService.getOfficers()
.subscribe(officers => this.officers = officers),
error => this.errorMessage = <any> error;
}
And service code
import { Injectable } from 'angular2/core';
import { Http, Response } from 'angular2/http';
import { Observable } from 'rxjs/Observable';
import { Officer } from '../shared/officer';
#Injectable()
export class OfficerService{
private _officerUrl = 'api/officers.json';
constructor(private _http: Http){ }
getOfficers() : Observable<Officer[]>{
return this._http.get(this._officerUrl)
.map((response: Response) => <Officer[]>response.json())
.catch(this.handleError);
}
private handleError(error: Response){
console.error(error);
return Observable.throw(error.json().error || 'Server error');
}
}
That is returning the data as an array and casting it to the correct type though you can also use any and return [0] if you just expect one.
Hope that helps