C#-模型总是获取其默认值

我有一个

ASP.Net Core 2.1

应用程序

下面是我的DTO

public class Movie
{
  public int Id { get; set;}

  public bool IsSpecial {get; set;}

  public IEnumerable<Ticket> Tickets { get; set; }

    public Movie()
    {
        if(IsSpecial)
        {
            this.Tickets = new List<TicketSpecial>();
        }
        else
        {
            this.Tickets = new List<Ticket>();
        }
    }}}

TicketsSpecial（子类/派生类）

WebAPI控制器

public class MovieController : ControllerBase
{

  public IActionResult Post([FromBody]Movie movie)
  {
  }
}

邮递员（HTTPPost-Req有效负载

Content-Type=application/json

）

当我通过Postman&debug在Movie-ctor调用上述API时，它总是捕获

IsSpecial=false

&所有字段的默认值（例如字符串类型null）

谢谢

将“Isspecial”更改为“Isspecial”，与其他属性相同

---

另一个问题是，您正在检查构造函数中的“IsSpecial”，此时它无论如何都应该为false。

当前实现中存在两个问题。首先，您的请求json对于嵌套属性无效，json反序列化程序不会使用

TicketsSpecial

为您反序列化

按照以下步骤进行解决方法：

电影

public class Movie
{
        public int Id { get; set; }

        public bool IsSpecial { get; set; }

        public IEnumerable<Ticket> Tickets { get; set; }

}

注册

MyJsonInputFormatter

public class MyJsonInputFormatter : JsonInputFormatter
{
        public MyJsonInputFormatter(ILogger logger, JsonSerializerSettings serializerSettings, ArrayPool<char> charPool, ObjectPoolProvider objectPoolProvider, MvcOptions options, MvcJsonOptions jsonOptions) : base(logger, serializerSettings, charPool, objectPoolProvider, options, jsonOptions)
        {

        }
        public override async Task<InputFormatterResult> ReadRequestBodyAsync(InputFormatterContext context)
        {
        var result = await base.ReadRequestBodyAsync(context);
        if (result.Model is Movie movie && movie.IsSpecial)
        {
                context.HttpContext.Request.Body.Position = 0;
                string request = await new StreamReader(context.HttpContext.Request.Body).ReadToEndAsync();
                var tickets = JObject.Parse(request)["Tickets"].ToObject<List<TicketSpecial>>();
                movie.Tickets = tickets;
        }
        return result;
        }
}

services.AddMvc(o =>
{
        var serviceProvider = services.BuildServiceProvider();
        var customJsonInputFormatter = new MyJsonInputFormatter(
                        serviceProvider.GetRequiredService<ILoggerFactory>().CreateLogger<MyJsonInputFormatter>(),
                        serviceProvider.GetRequiredService<IOptions<MvcJsonOptions>>().Value.SerializerSettings,
                        serviceProvider.GetRequiredService<ArrayPool<char>>(),
                        serviceProvider.GetRequiredService<ObjectPoolProvider>(),
                        o,
                        serviceProvider.GetRequiredService<IOptions<MvcJsonOptions>>().Value
                );

        o.InputFormatters.Insert(0, customJsonInputFormatter);
})

---

IsSpecial

在构造期间将始终为false，您需要将其值传递给构造函数或更改属性的setter来构建集合。您正在发出的http请求是什么？显示您如何通过PostMani调用它如果我是您，我就不会费心创建模型类的层次结构，只需创建一个处理这两种情况的票据模型（标准和正常）。它与创建请求的方式无关，

IsSpecial

在执行

if（IsSpecial）

时尚未初始化

public class Movie
{
        public int Id { get; set; }

        public bool IsSpecial { get; set; }

        public IEnumerable<Ticket> Tickets { get; set; }

}

public class MyJsonInputFormatter : JsonInputFormatter
{
        public MyJsonInputFormatter(ILogger logger, JsonSerializerSettings serializerSettings, ArrayPool<char> charPool, ObjectPoolProvider objectPoolProvider, MvcOptions options, MvcJsonOptions jsonOptions) : base(logger, serializerSettings, charPool, objectPoolProvider, options, jsonOptions)
        {

        }
        public override async Task<InputFormatterResult> ReadRequestBodyAsync(InputFormatterContext context)
        {
        var result = await base.ReadRequestBodyAsync(context);
        if (result.Model is Movie movie && movie.IsSpecial)
        {
                context.HttpContext.Request.Body.Position = 0;
                string request = await new StreamReader(context.HttpContext.Request.Body).ReadToEndAsync();
                var tickets = JObject.Parse(request)["Tickets"].ToObject<List<TicketSpecial>>();
                movie.Tickets = tickets;
        }
        return result;
        }
}

services.AddMvc(o =>
{
        var serviceProvider = services.BuildServiceProvider();
        var customJsonInputFormatter = new MyJsonInputFormatter(
                        serviceProvider.GetRequiredService<ILoggerFactory>().CreateLogger<MyJsonInputFormatter>(),
                        serviceProvider.GetRequiredService<IOptions<MvcJsonOptions>>().Value.SerializerSettings,
                        serviceProvider.GetRequiredService<ArrayPool<char>>(),
                        serviceProvider.GetRequiredService<ObjectPoolProvider>(),
                        o,
                        serviceProvider.GetRequiredService<IOptions<MvcJsonOptions>>().Value
                );

        o.InputFormatters.Insert(0, customJsonInputFormatter);
})

        {
                "IsSpecial": true,
                "Tickets":  [
                                {"SpecialProp1": "Mumbai Test"}
                        ]
        }