Issue with Deserialization of Enum to string using System.Text.JSON

Question

I am currently using .NET 6 and System.Text.Json for serialization. I am having issues where system.text.json does not deserialize the enum to string properly when I return the response using OkObjectResult or ObjectResult

I have used the following on model

public class Customer
{
    public string? id { get; set; }

    public string? Name { get; set; }
    
    public string Address { get; set; }
    
    [JsonConverter(typeof(JsonStringEnumConverter))]
    public CustomerType Type {get; set;}
}

using System.Text.Json.Serialization;

[JsonConverter(typeof(JsonStringEnumConverter))]
public enum CustomerType
{
    NEW,
    EXISTING
}

Now the API Code

public async Task<IActionResult> GetCustomerById(string Id)
    {
        var results = await _customerService.GetData(Id);
        // The results have correct JSON data with enum as string but as soon as I pass this to OkObjectResult, it changes the enum back to int
        return new OkObjectResult(results );
           
    }

Service

public async Task<Customer> GetData(string Id)
    {
        var results = await _httpClient.SendAsync(Id);  // Get Data
        var jsonResults = await results.Content.ReadAsStringAsync();
       var options = new JsonSerializerOptions{ Converters ={
        new JsonStringEnumConverter()};

        return JsonSerializer.Deserialize<Customer>(jsonResults ,
            options ) ;  // This returns the data correctly
}

Now my question why OkObjectResult breaks the code and return the integer instead of enum string value

Answer 1

One of the reason can be related to the fact that you are registering multiple Json serialize options: Jsone & NewtonsoftJson at the same time. Keeping only one may resolve the issue.