Angular 6: unable to make http request

问题:

In my angular application, I am trying to make the http post request to the spring restful API.. but I could not succeed.. I am not getting any error response in the browser console..

My angular code is,

addToCart(productId: number, quantity: number) {
    const headers = new HttpHeaders().set('Content-Type', 'text/plain; charset=utf-8');
    console.log("--------order.service.ts----------addToCart()-------productId:"+productId+":------quantity:"+quantity);
     this.http.post('http://localhost:8080/order/addtocart', 
              '{ "dealerId": 9, "createdBy": "-1", "productId": productId, "quantity": quantity}', 
              {headers: headers})
              .pipe(catchError(this.errorHandlerService.handleError));
    }

Spring restful API:

package com.wocs.rest.controller;

import java.io.IOException;
import java.util.Map;

import org.apache.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.wocs.services.common.ServiceException;
import com.wocs.services.order.iface.OrderServiceIface;
import com.wocs.services.userrole.model.User;

@RestController()
@RequestMapping("/order")
public class OrderController {

    static Logger logger = Logger.getLogger(OrderController.class);

    @Autowired
    private OrderServiceIface orderService;

    public void setOrderService(OrderServiceIface orderService) {
        this.orderService = orderService;
    }

    @RequestMapping(value = "/addtocart", method = RequestMethod.POST, consumes = "text/plain")
    public void addToCart(@RequestBody String stringRequestBody) throws JsonParseException, JsonMappingException, IOException, ServiceException
    {
        logger.info("addtocart:"+stringRequestBody);
        Map<String, Object> jsonMap = new ObjectMapper().readValue(stringRequestBody,
            new TypeReference<Map<String,Object>>(){});

         orderService.addToCart((Integer)jsonMap.get("dealerId"), (String) jsonMap.get("createdBy"), (Integer)jsonMap.get("productId"), (Integer)jsonMap.get("quantity"));
    }

}

Browser console:

Any help would be appreciated.. Thanks in advance..

回答1:

You missed the subscription. If you have declared addToCart in service and want to handle API response in component modify code as:

service

addToCart(productId: number, quantity: number) {
    let data = { 
        "dealerId": 9, 
        "createdBy": "-1", 
        "productId": productId, 
        "quantity": quantity
    }
    const headers = new HttpHeaders().set('Content-Type', 'text/plain; charset=utf-8');
    console.log("--------order.service.ts----------addToCart()-------productId:"+productId+":------quantity:"+quantity);
    return this.http.post('http://localhost:8080/order/addtocart', 
              JSON.stringify(data), 
              {headers: headers})
              .pipe(catchError(this.errorHandlerService.handleError));
}

component subscribe service method

this.service.addToCart(2, 4).subscribe(res => {
    console.log(res); // Response from API
})

回答2:

You are not subscribing to the this.http.post(...) function, which returns an observable.

An observable does nothing until you subscribe to it, so you code should be:

addToCart(productId: number, quantity: number) {
    const headers = new HttpHeaders().set('Content-Type', 'text/plain; charset=utf-8');

    this.http.post('http://localhost:8080/order/addtocart', 
          '{ "dealerId": 9, "createdBy": "-1", "productId": productId, "quantity": quantity}', 
          {headers: headers})
          .pipe(catchError(this.errorHandlerService.handleError))
          .subscribe(data => {
              // Handle the updated data here.
              console.log(data);
          });
}         

Alternatively you can use an async pipe to handle the subscription for you, if you get any data back which can be used in a view directly.