角2無法調用節點服務器的Http調用

Question

我沒有調用到節點服務器的Http調用。

呼叫從以下組件啓動：

@Component({ 
    selector: 'app-special-value', 
    templateUrl: './special-value.component.html', 
    styleUrls: ['./special-value.component.css'] 
}) 

export class SpecialValueComponent implements OnInit { 

    constructor(private dataService: DataService) { } 

    ngOnInit() { 
    this.getSpecialValueProducts(); 
    } 

    getSpecialValueProducts() { 
    this.dataService.getSpecialValueProducts(); 
    } 

} 

服務的getSpecialValueproducts（）被調用它調用節點服務器：

@Injectable() 
export class DataService { 
private specialValueUrl = "/api/product/specialvalue"; 

    constructor(private http: Http) { } 

    getSpecialValueProducts() { 
    console.log('getSpecialValueProducts() called'); 

    return this.http.get(this.specialValueUrl) 
     .map((response: Response) => response.json()) 
     .catch(this.handleError); 
    } 
} 

到數據庫的連接是成功的。但從數據服務到節點功能的後續調用從不會被調用。

const express = require('express'); 
const router = express.Router(); 
const mongoose = require('mongoose'); 

const Product = require('../models/product'); 

module.exports = router; 

const url = "mongodb://xxxxxx:xxxxxxu@xxxxx.mlab.com:111111/xxxxxx"; 

mongoose.Promise = global.Promise; 
mongoose.createConnection(url, function(err) { 
    if(err) { 
     console.log('Error!!!' + err); 
    } else { 
     console.log('Connected to Database!'); 
    } 
}); 

router.get('/product/specialvalue', function(req, res) { 
    console.log('Get specialvalue called '); 

Product.find({'specialValue': true}) 
.sort({'price': 1}) 
.exec(function(err, products) { 
    if(err) { 
     console.error('Error retrieving special value products!'); 
    } else { 
     console.log("products = " + JSON.stringify(products)); 
     res.json(products);   
    } 
}) 

}) 

節點服務器：

const express = require('express'); 
const bodyParser = require('body-parser'); 
const path = require('path'); 

const api = require('./server/routes/api'); 
const port = 4200; 

const app = express(); 
app.use(express.static(path.join(__dirname, 'dist'))); 

app.use(bodyParser.urlencoded({extended: true})); 
app.use(bodyParser.json()); 

app.use('/api', api); 

app.get('*', (req, res) => { 
    res.sendFile(path.join(__dirname, 'dist/index.html')); 
}); 

app.listen(port, function() { 
    console.log('@@@@ nglowes01 Server running on localhost: ' + port); 
}) 

Answer 1

看起來你缺少subscribe。它不會執行http請求，直到您訂閱。這樣的事情：

@Component({ 
    selector: 'app-special-value', 
    templateUrl: './special-value.component.html', 
    styleUrls: ['./special-value.component.css'] 
}) 

export class SpecialValueComponent implements OnInit { 
    specialValue; 

    constructor(private dataService: DataService) { } 

    ngOnInit() { 
    this.getSpecialValueProducts(); 
    } 

    getSpecialValueProducts() { 
    this.dataService.getSpecialValueProducts().subscribe(value => this.specialValue = value); 
    } 

}