Spring Boot接收Angular订单数据失败：JSON反序列化错误排查

问题概述 #

从Angular应用向Spring Boot发送订单数据，客户端创建订单后发送至服务器，但服务器无法正确接收对象。

前端待发送数据（格式验证正确） #

{
    "user": {
        "username": "Yomerito",
        "address": "Aquimerito 1234, Roswell NM 88000",
        "credit": "4444-0000-0000-0001"
    },
    "cart": [
        {
            "id": 2,
            "foodName": "Tacos de Barbacoa",
            "price": 20,
            "cuisine": "MEXICAN",
            "description": "Borrego\nasado en horno de piedra ",
            "isEnabled": "Y",
            "imageUrl": "tinyurl\n.com/moleVerdeImage"
        },
        {
            "id": 1,
            "foodName": "Kebab",
            "price": 10,
            "cuisine": "ARAB",
            "description": "rico Kebab",
            "isEnabled": "Y",
            "imageUrl": "tinyurl\n.com/moleVerdeImage"
        }
    ],
    "status": "PENDING"
}

Angular 核心代码 #

1. 订单创建与提交方法 #

onSubmit(): void {
    this.purchaseService.postPurchase(this.createOrder()).subscribe({
        next: (data: any) => {
            let retVal = JSON.parse(JSON.stringify(data))
            if (retVal === ("OK")) {
                this.router.navigate(["/purchase"])
            }
        },
        error: err => {
            console.error(err.message)
            alert("onSubmit error: " + err.message);
        }
    });
}

createOrder(): IOrden {
    this.searchService.orden = {user: this.checkoutForm.value, cart: this.searchService.cart, status: "PEND"}
}

Spring Boot 后端代码 #

订单接收Controller #

package com.slbootcamp.foodbox.controller;

import com.slbootcamp.foodbox.entity.Orden;
import com.slbootcamp.foodbox.entity.User;
import com.slbootcamp.foodbox.jdbc.OrdenDao;
import com.slbootcamp.foodbox.jdbc.UserDao;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@CrossOrigin(origins ="*", allowedHeaders = "*")
@RestController
public class OrdenController {

    private Logger logger = LoggerFactory.getLogger(this.getClass());

    @Autowired
    OrdenDao ordenDao;

    @PostMapping("/cart/placeOrden")
    public int placeOrden(@RequestBody Orden orden) {
//    public int placeOrden(@ModelAttribute Orden orden) {
        logger.info("---------------> Orden: " + orden);
        return ordenDao.placeOrden(orden);
    }
}

遇到的错误 #

1. 使用@RequestBody时的反序列化错误 #

Resolved [org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot deserialize value of type `com.slbootcamp.foodbox.entity.Cart` from Array value (token `JsonToken.START_ARRAY`); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `com.slbootcamp.foodbox.entity.Cart` from Array value (token `JsonToken.START_ARRAY`)<EOL> at [Source: (org.springframework.util.StreamUtils$NonClosingInputStream); line: 1, column: 117] (through reference chain: com.slbootcamp.foodbox.entity.Orden["cart"])]

2. 使用@ModelAttribute时的属性空值问题 #

---------------> Orden: Orden(status=null, cart=null, user=null)

排查指导 #

• 修正后端实体类字段类型：错误提示明确说明无法将数组反序列化为单个Cart对象，需将Orden类中的cart字段定义改为List<Cart>或Cart[]类型。
• 修复Angular方法返回值：当前createOrder()方法没有返回值，导致传给postPurchase的是undefined。修改方法返回创建好的订单对象：

  createOrder(): IOrden {
    const orden = {user: this.checkoutForm.value, cart: this.searchService.cart, status: "PEND"};
    this.searchService.orden = orden;
    return orden;
  }
  

• 校验前后端字段一致性：检查Orden、User、Cart实体类的字段名与前端JSON键名完全匹配（包括大小写，比如前端foodName对应后端foodName而非foodname）；同时注意前端status值为PENDING，但代码中写的是PEND，需确认后端是否兼容该值。
• 确认请求头格式：确保Angular请求的Content-Type为application/json（HttpClient默认配置），若误用form-data格式，@RequestBody无法解析，@ModelAttribute也需要字段名严格对应。
• 验证实际请求体：通过浏览器开发者工具的Network标签，查看实际发送的请求体是否与控制台打印的一致，排查代码中对象序列化后的潜在差异。

内容的提问来源于stack exchange，提问作者Gianni Fontanot