ASP.NET 核心 JSON 模型将 int 绑定到枚举

如何解决ASP.NET 核心 JSON 模型将 int 绑定到枚举

场景

我想将具有整数值的传入 JSON 请求映射到相应的枚举值。 下面的代码针对实际问题进行了简化，MyRequest 类中有更多的字段。

数据代码

public enum Policy
{
    UnkNown = 0,Policy1 = 1,Anticipated = 2
}

public enum Design
{
    UnkNown = 0,Project = 1,Days = 2
}

public class Policies
{
    public Policy? PolicyId { get; set; } 

    public Design? DesignId { get; set; } 
}

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

    public Policies Policies { get; set; }
}

JSON 请求

{
    "policies": {
        "policyId": 2,"designId": 2
    },"id": 1
}

控制器代码

[HttpPut]
public async Task<IActionResult> Put(MyRequest request)
{
    // reques.Policies.DesignId is null
    // reques.Policies.PolicyId is null
}

解决方法

在深入研究问题之后，并且几乎微软没有文档，我发现了 this 类似的问题，它给了我正确的方向：实现自定义 JSONConverter。 >

JSONConverter

public class ContractConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return typeof(Policies) == objectType;
    }

    public override object ReadJson(JsonReader reader,Type objectType,object existingValue,JsonSerializer serializer)
    {
        var rawValue = serializer.Deserialize<dynamic>(reader);
        var policyId = (Policy)(rawValue.policyId);
        var designId = (Design)(rawValue.designId);
        return new Policies(policyId,designId);
    }

    public override void WriteJson(JsonWriter writer,object value,JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }

    public override bool CanWrite => false;
}

Startup.cs

 services.AddControllers()
                .AddNewtonsoftJson(o=> o.SerializerSettings.Converters.Add(new ContractConverter()));