ASP.NET Core Optional Json Fields
Also featured in this article is enum to string converter.
ASP.NET Backend
builder.Services.AddControllersWithViews(options => {
options.Conventions.Add(new RouteTokenTransformerConvention(
new SlugifyParameterTransformer()));
}).AddJsonOptions(options => {
options.JsonSerializerOptions.NumberHandling = JsonNumberHandling.AllowReadingFromString;
options.JsonSerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase; // JSON response is in camelCase
options.JsonSerializerOptions.DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull; // null not serialized
options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter()); // enums to string
// options.JsonSerializerOptions.IncludeFields = true; // if you want to [de]serialize fields (i.e. get or set are omitted in the class)
});
Client Side
internal class Api {
// Insert variables below here
protected static HttpClient _client;
protected static string BASE_URL = "http://10.0.2.2:5284/";
// protected static string BASE_URL = "https://api.domain.com/";
private static readonly ILogger _logger = typeof(Api).Log();
private static JsonSerializerOptions _serializerOptions;
static Api() {
_client = new HttpClient();
_serializerOptions = new() {
PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
};
_serializerOptions.Converters.Add(new JsonStringEnumConverter());
}
public string serializePayload<T>(T value) {
return JsonSerializer.Serialize(value, _serializerOptions);
}
public T deserializePayload<T>(string payload) {
return JsonSerializer.Deserialize<T>(payload, _serializerOptions);
}
}
Generalized
Fields
Since System.Text.Json is only
| Field | Description |
|---|---|
| Always | Property is always ignored. |
| Never | Property is always serialized and deserialized, regardless of IgnoreNullValues configuration. |
| WhenWritingDefault | Property is ignored only if it equals the default value for its type. |
| WhenWritingNull | Property is ignored if its value is null. This is applied only to reference-type properties and fields. |
For readers in a decade or so, see JsonIgnoreCondition
using System.Text.Json.Serialization;
namespace MyApi.Models;
public enum LoginErrors {
InvalidEmail,
TooManyRequests,
}
public class StartLoginResponse {
[JsonConverter(typeof(JsonStringEnumConverter))]
// this right here:
[JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
public LoginErrors? Error { get; set; }
}