AspNet 3.1 - Collides with another property : ThrowInvalidOperationException_SerializerPropertyNameConflict

Question

My Error is that the controller is not able to map the value; I have this situation that explains how to replicate the error:

    public class FooA {
      public string Property1 { set; get; }
      public virtual string Property2 { set; get; }
    }
    
    public class FooB : FooA {
      public new string Property2 { set; get; } 
      public string Property3 { set; get; }
    }

As you know, the property Property2 is common for both classes, thereby when you are using in any controller this action:

    public async task<string> ActionA([FromBody] FooA fooA)
    {
      return string.Empty;
    }


    // The error is thrown in this unwrapping.
    public async task<string> ActionB([FromBody] FooB fooB)
    {
      return string.Empty;
    }

The payload for FooA is of the request is:

    {
      "Property1" : "abc",
      "Property2" : "def"
    }

The payload for FooB is of the request is:

    {
      "Property2" : "abc",
      "Property3" : "def"
    }

This Exception will be thrown:

    System.InvalidOperationException: The JSON property name for 'FooB' collides with another property.
       at System.Text.Json.ThrowHelper.ThrowInvalidOperationException_SerializerPropertyNameConflict(JsonClassInfo jsonClassInfo, JsonPropertyInfo jsonPropertyInfo)
       at System.Text.Json.JsonClassInfo..ctor(Type type, JsonSerializerOptions options)

I have added Attributes such as [JsonIgnore] but it fails with a payload like the first one.

or :

            services.AddControllers()
                .AddJsonOptions(options =>
                    {
                        options.JsonSerializerOptions.PropertyNamingPolicy = null;
                        options.JsonSerializerOptions.PropertyNameCaseInsensitive = false;
                    });

But it has not possible, my idea is to be SOLID and avoid to change the entire solution. It means Open Extensions (it means that extensions will solve future issues ) Closed to (already implemented) changes.

Do you have a particular setting in the AddJsonOptions to allow that conflicts by inheritences will be autoresolved using the child class always?

Notes 01: Even, when it is added the virtual ans new reserver keyword the controller throws the same exceptions.

Answer 1

you have to fix the classes, you have 2 choices

the common one

public class FooA
{
    public string Property1 { set; get; }
    public virtual string Property2 { set; get; }
}

public class FooB : FooA
{
    public override string Property2 { set; get; }
    public string Property3 { set; get; }
}

or if you want to have an access to 2 properties

public class FooA
{
    public string Property1 { set; get; }
    public string Property2 { set; get; }
}

public class FooB : FooA
{
    public new string Property2 { set; get; }
    public string Property3 { set; get; }
}

test

var json = @"{
      ""Property2"" : ""abc"",
      ""Property3"" : ""def""
    }";

var jsonDeserialized=System.Text.Json.JsonSerializer.Deserialize<FooB>(json);

test reslut (in a json format)

{
  "Property2": "abc",
  "Property3": "def",
  "Property1": null
}

but I recommend you to install Newtonsoft.Json serializer just config it in startup

using Newtonsoft.Json.Serialization;

    services.AddControllersWithViews()
    .AddNewtonsoftJson(options =>
           options.SerializerSettings.ContractResolver =
              new CamelCasePropertyNamesContractResolver());

or if you use just controllers

    services.AddControllers()
    .AddNewtonsoftJson(options =>
           options.SerializerSettings.ContractResolver =
              new CamelCasePropertyNamesContractResolver());