JsonSerializer.Deserialize 返回空对象

Question

我有一个返回一些 Json 的 webapi：

{"id":9,"businessName":"dummy","address":"pluto","products":[
{"id":762,"description":"Centralized needs-based website","price":1281.24,"stock":1600,"categories":[],"factory":null},
{"id":1027,"description":"Realigned 6th generation knowledge base","price":2398.16,"stock":19583,"categories":[],"factory":null},
{"id":1392,"description":"User-centric zero administration array","price":998.07,"stock":6124,"categories":[],"factory":null},
{"id":1800,"description":"Team-oriented reciprocal core","price":4422.95,"stock":17372,"categories":[],"factory":null},
{"id":2763,"description":"Sharable needs-based hierarchy","price":4122.98,"stock":17397,"categories":[],"factory":null},
{"id":6189,"description":"Re-engineered hybrid emulation","price":395.09,"stock":532,"categories":[],"factory":null}
]}

然后我尝试使用以下方法反序列化：

using var response = await _httpClient.GetAsync($"{GetApiRouteFromEntity(entity)}/{entity.GetId()}");
        response.EnsureSuccessStatusCode();
        var responseContent = await response.Content.ReadAsStringAsync();
        T? item = JsonSerializer.Deserialize<T>(responseContent);

但这给了我一个空工厂，id为0，所有其他属性为null

工厂.cs

public class Factory : EntityBase
    {
        [DisplayName("ID")]
        public int Id { get; set; }

        [DisplayName("Nome Business")]
        public string? BusinessName { get; set; }

        [DisplayName("Indirizzo")]
        public string? Address { get; set; }

        [DisplayName("Prodotti")] 
        public virtual ICollection<Product> Products { get; set; }
        
        public override string ToString()
        {
            return $"[{Id}] {BusinessName}";
        }
    }

产品.cs

public class Product : EntityBase
    {
        [DisplayName("ID")]
        public int Id { get; set; }

        [DisplayName("Descrizione")]
        public string? Description { get; set; }

        [DisplayName("Prezzo")]
        public float Price { get; set; }

        [DisplayName("Magazzino")]
        public int Stock { get; set; }

        [DisplayName("Categorie")]
        public virtual ICollection<Category> Categories { get; set; }

        [DisplayName("Fabbrica")]
        public virtual Factory Factory { get; set; }

        public override string ToString()
        {
            return $"[{Id}] {Description}";
        }
    }

EntityBase.cs

public abstract class EntityBase
    {
        public virtual object GetId()
        {
            return GetType().GetProperty("Id").GetValue(this);
        }
    }

我猜这是因为产品中的工厂道具为空，但我不知道如何解决这个问题

Answer 1

JSON 键都是驼峰式大小写，但类中的 props 是用帕斯卡式大小写编写的。例如businessName对BusinessName.. 因此 JsonSerializer 无法匹配它们。

您可以像这样初始化序列化器以忽略大小写的差异：

var options = new JsonSerializerOptions
{
    PropertyNameCaseInsensitive = true
};
T? item = JsonSerializer.Deserialize<T>(responseContent, options);

有关更多信息，请参阅文档：https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json-character-casing

Answer 2

来自文档：

默认情况下，属性名称和字典键在 JSON 输出中保持不变，包括大小写。

您可以指定属性命名策略：

T? item = JsonSerializer.Deserialize<T>(responseContent, new JsonSerializerOptions
{
    PropertyNamingPolicy = JsonNamingPolicy.CamelCase
});

对所有 JSON 属性名称使用驼峰式大小写，或使用包含JsonPropertyNameAttibute正确名称的方式标记所有需要的属性：

public class Factory : EntityBase
{
    [DisplayName("ID")]
    [JsonPropertyName("id")] // and so on
    public int Id { get; set; }
    ....
}

或者设置JsonSerializerOptions.PropertyNameCaseInsensitive为true.