ASP.NET 核心 JSON 模型绑定 int 到枚举

Question

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。下面的代码针对问题进行了简化，实际上 MyRequest class.

上有更多字段

数据码


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
}

Answer 1

在更深入地研究这个问题并且几乎 没有微软文档 之后，我发现 this 类似的问题给了我正确的方向：实施自定义 JSONConverter.

JSON转换器

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()));

ASP.NET 核心 JSON 模型绑定 int 到枚举

ASP.NET core JSON model binding int to enum

enums

integer

model-binding

asp.net-core-3.1

场景

数据码

JSON请求

控制器代码

JSON转换器

Startup.cs