ASP .Net core web api serialization issue for property names with underscore

Question

The simplest version of the problem is shown by creating a new ASP .NET core web api project. Adding this class

public class TestClass
{
    public string AAAA_BBBB { get; set; } = "1";
}

And this controller method

[HttpGet("GetTestClass")]
public TestClass GetTestClass()
{
   return new TestClass();
}

results in this response

{
   "aaaA_BBBB": "1"
}

After experimenting, it looks like anything which has an underscore in it is treated this way. All the characters in the bit before the FIRST underscore except for the last character in that set get converted into lower case.

So

AAAA_BBBB becomes aaaA_BBBB
AAAAAAAA_BBB_CCC_DDD becomes aaaaaaaA_BBB_CCC_DDD
A_BBB becomes a_BBBB
AA_BB becomes aA_BB

Why is this happening and how do I fix it?

The default one used by WebAPI. Not doing anything special for it — Ash
– Ash, Commented Jul 8, 2022 at 1:22

Chen · Accepted Answer · 2022-07-08 02:41:37Z

2

By default Web API serializes the fields of types that have a [Serializable] attribute (e.g. Version).That's what the Web API guys wanted.

You can decorate with a property name like so:

[JsonPropertyName("AAAA_BBBB")]
public string AAAA_BBBB { get; set; } = "1";

Or,you can refer to these two links:Link1 and Link2 to stop Web API doing it in JSON.

Update

The same effect can be achieved using the following code in Startup：

services.AddControllersWithViews().
                AddJsonOptions(options =>
                {
                    options.JsonSerializerOptions.PropertyNameCaseInsensitive = true;
                    options.JsonSerializerOptions.PropertyNamingPolicy = null;
                });

edited Jul 8, 2022 at 2:41

answered Jul 7, 2022 at 9:01

Chen

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2 Comments

Ash Over a year ago

This solution works but I can't use it due to certain constraints. I'm using .net 5.0 frmaework. The code in the links you posted build if I add a reference to Microsoft.AspNet.WebAPI/5.2.9 but it looks like this is meant for projects target .netFramework4.8 because I keep getting an error I cant get around -> Could not load type "System.Web.Routing.RouteTable" This is the bit of code I'm trying to get working

var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter;              json.UseDataContractJsonSerializer = true;

Chen Over a year ago

I updated my answer, you can test it.@Ash

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