Salesforce Apex调用外部API反序列化失败，对象数据为空

核心问题总结 #

导致反序列化后字段全为null的原因有以下4点：

• JSON结构不匹配：返回的JSON根对象包含Product_Catagories数组，而非单个Product_Catagories实例，直接反序列化到单个对象会完全无法匹配数据
• 字段大小写不匹配：Apex JSON反序列化默认区分大小写，JSON中的ProductFamily、RelatedProducts与类中定义的productFamily、relatedProducts大小写不一致，导致字段无法映射
• 数据类型不匹配：JSON中productfeatures是数组类型，但Apex类中定义为单个POCProductfeature对象，类型不匹配导致赋值失败
• 请求头拼写错误：Content-Type写成了application/jsson，正确应为application/json，可能引发API返回异常或格式错误

修正步骤 #

1. 定义外层包装类 #

创建匹配JSON根结构的包装类，用来承载Product_Catagories数组：

public class POCResponseWrapper {
    public List<Product_Catagories> Product_Catagories;
}

2. 修正字段匹配与类型 #

有两种方式解决大小写匹配问题，同时修正productfeatures的类型：

• 方式一：直接修改Apex字段名，与JSON键名完全一致（简单直接）

  public class Product_Catagories {
      public String id;
      public String name;
      public String description;
      public String region;
      public String category; 
      public String ProductFamily; // 与JSON键名一致
      public String RelatedProducts; // 与JSON键名一致
      public List<POCProductfeature> productfeatures; // 改为数组类型
  }
  

• 方式二：使用@JsonProperty注解指定JSON键名（适合无法修改字段名的场景）

  public class Product_Catagories {
      public String id;
      public String name;
      public String description;
      public String region;
      public String category; 
      @JsonProperty('ProductFamily')
      public String productFamily;
      @JsonProperty('RelatedProducts')
      public String relatedProducts;
      public List<POCProductfeature> productfeatures; // 改为数组类型
  }
  

3. 修正反序列化与请求逻辑 #

调整反序列化目标类型为包装类，同时修正请求头拼写：

private static List<Product_Catagories> getPOCProducts(){
    Http h = new Http();
    String method = 'GET';
    String url = 'https://externalapi';
    HttpRequest req = new HttpRequest();

    req.setEndpoint(url);
    req.setMethod(method);      
    req.setTimeout(120000);
    req.setHeader('Content-Type', 'application/json'); // 修正拼写错误
    req.setHeader('subscription-Key','db163fc326d***');
    HttpResponse res = h.send(req);
    
    // 先反序列化为包装类，再提取数组数据
    POCResponseWrapper responseWrapper = (POCResponseWrapper)System.JSON.deserialize(res.getBody(), POCResponseWrapper.class);
    system.debug('Data: ' + responseWrapper.Product_Catagories);
    return responseWrapper.Product_Catagories;
}

4. 修正getPOCCats方法 #

因为getPOCProducts现在直接返回数组，无需再包装：

public static List<Product_Catagories> getPOCCats(){
    return getPOCProducts();
}

完整修正代码 #

public class POCGetCategories {
    
    public static List<Product_Catagories> getPOCCats(){
        return getPOCProducts();
    }
    
    // 外层包装类，匹配JSON根结构
    public class POCResponseWrapper {
        public List<Product_Catagories> Product_Catagories;
    }

    public class Product_Catagories {
        public String id;
        public String name;
        public String description;
        public String region;
        public String category; 
        public String ProductFamily; // 与JSON键名一致
        public String RelatedProducts; // 与JSON键名一致
        public List<POCProductfeature> productfeatures; // 改为数组类型
    }

    public class POCProductfeature {
        public String id;
        public String name;
        public String code;
        public String status;
        public String description;
    }

    private static List<Product_Catagories> getPOCProducts(){
        Http h = new Http();
        String method = 'GET';
        String url = 'https://externalapi';
        HttpRequest req = new HttpRequest();

        req.setEndpoint(url);
        req.setMethod(method);      
        req.setTimeout(120000);
        req.setHeader('Content-Type', 'application/json'); // 修正拼写错误
        req.setHeader('subscription-Key','db163fc326d***');
        HttpResponse res = h.send(req);
        
        POCResponseWrapper responseWrapper = (POCResponseWrapper)System.JSON.deserialize(res.getBody(), POCResponseWrapper.class);
        system.debug('Data: ' + responseWrapper.Product_Catagories);
        return responseWrapper.Product_Catagories;
    }
}

内容的提问来源于stack exchange，提问作者Hasan Zubairi