Angular DataService cant resolve parameters

Question

I am using Angular v.4.2.4. When I try to get data from an API I get an error I cant seem to find. The API is on my own machine and is returning data as it should in postman. The error I am getting is:

Can't resolve all parameters for DataService

Here are my files I thought would help to find the error:

app.module

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { HttpClientModule } from '@angular/common/http';    

import { AppComponent } from './app.component';
import { ProductComponent } from './shop/product.component';
import { DataService } from './shared/dataService';

@NgModule({
    declarations: [       
        AppComponent,
        ProductComponent
    ],
    imports: [
        BrowserModule,
        HttpClientModule
    ],
    providers: [DataService],
    bootstrap: [AppComponent]
})
export class AppModule { }

dataService

import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';
import 'rxjs/add/operator/map';
import { Product } from './product';

Injectable()
export class DataService {

    constructor(private http: HttpClient) { }

    public products: Product[] = [];

    loadProducts(): Observable<boolean>{
        return this.http.get('/api/products')
            .map((data: any[]) => {
                this.products = data;
                return true;
            })
    }
}

product.component

import { Component, OnInit } from "@angular/core";
import { DataService } from '../shared/dataService';
import { Product } from '../shared/product';  


@Component({
    selector: "product-list",
    templateUrl: "productList.component.html",
    styleUrls: []
})

export class ProductComponent implements OnInit {

    constructor(private data: DataService) { }

    public products: Product[] = [];

    ngOnInit(): void {
        this.data.loadProducts()
            .subscribe(success => {
                if (success) {
                    this.products = this.data.products;
                }
            });
    }
}

Tell me if you want to see anything else. Thanks for all the help.

Answer 1

you need to provide some data value as parameter in your 'product' api in your product component.

this.data.loadProducts({'url': '/api/products', 'data':{
'x': ''
}}).subscribe(success =>{
console.log(success);
})

in your dataService

loadProducts(data): Observable<boolean>{
    return this.http.get(data.url, data.data)
        .map((data: any[]) => {
            this.products = data;
            return true;
        })
}