c#asp.net-core dotnet-httpclient system.text.json .net-8.0

.NET 8 Httpclient post parameter changing it's case to camel

I have a strange issue using IhttpClientFactory named client.
The "POST" body parameter are changing it's case to camel "initCap". I have written some Handlers (delegate handler) for adding "http headers", "exception handling" and "audit logging".
The parameters are changing the case to camelcase.

My Model class

 public class PostRequest
 {
    [DataMember(Name = "Request", EmitDefaultValue = false)]
    public Request? Request { get; set; }
 }

I know that the attribute is for Newtonsof json but tried JsonProperty as well but not working. .....

to get the response of the post call (inside a generic calss method

var httpContent = await client.PostAsJsonAsync(resource, requestBody, cancellationToken);
return await httpContent.Content.ReadFromJsonAsync<T>(cancellationToken: cancellationToken);

Anyone faced similar issue?

Solution

PostAsJsonAsync uses JsonSerializerDefaults.Web for serializer options by default which will result in Camel case property names and data contracts (DataMemeberAttribute) are not supported by System.Text.Json. If you want use another set of settings for serialization (i.e. Pascal case default serialization) - you can provide them. For example:

var httpContent = await client.PostAsJsonAsync(
    resource, 
    requestBody,
    new JsonSerializerOptions(), // TODO: configure as needed and reuse the options
    cancellationToken);

Or use the JsonPropertyNameAttribute (will need to mark all properties which require "non-default" handling). For example:

public class PostRequest
{
    [JsonPropertyName("Request")] // should be Pascal case no matter which System.Text.Json settings used
    public Request? Request { get; set; } 
}