Problem with Empty Json

Cannot create Object, when zeit_total_daily is empty

Jugenddienst Stunden/Models/Hours.cs

@@ -1,5 +1,6 @@
 
 using CommunityToolkit.Mvvm.ComponentModel;
+using Newtonsoft.Json;
 
 namespace Jugenddienst_Stunden.Models {
 	public class Hours : ObservableObject {
@@ -9,7 +10,11 @@ namespace Jugenddienst_Stunden.Models {
 		public Dictionary<int,NominalWeek> nominal_week_api;
 		//public List<string> time_line;
 		public string zeit_total;
-		public Dictionary<int,decimal>? zeit_total_daily;
+
+		//https://stackoverflow.com/questions/29449641/deserialize-json-when-a-value-can-be-an-object-or-an-empty-array/29450279#29450279
+
+		[JsonConverter(typeof(JsonSingleOrEmptyArrayConverter<Hours>))]
+		public Dictionary<int,decimal> zeit_total_daily;
 		//public List<string> wochensumme;
 		public string overtime_month;
 		public string overtime;

Jugenddienst Stunden/Models/JsonSingleOrEmptyArrayConverter.cs

@@ -0,0 +1,70 @@
+using Newtonsoft.Json;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Jugenddienst_Stunden.Models {
+	public class JsonSingleOrEmptyArrayConverter<T> : JsonConverter where T : class {
+		public override bool CanConvert(Type objectType) {
+			return typeof(T).IsAssignableFrom(objectType);
+		}
+
+		public override bool CanWrite { get { return false; } }
+
+		public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer) {
+			var contract = serializer.ContractResolver.ResolveContract(objectType);
+			if (!(contract is Newtonsoft.Json.Serialization.JsonObjectContract || contract is Newtonsoft.Json.Serialization.JsonDictionaryContract)) {
+				throw new JsonSerializationException(string.Format("Unsupported objectType {0} at {1}.", objectType, reader.Path));
+			}
+
+			switch (reader.SkipComments().TokenType) {
+				case JsonToken.StartArray: {
+						int count = 0;
+						while (reader.Read()) {
+							switch (reader.TokenType) {
+								case JsonToken.Comment:
+									break;
+								case JsonToken.EndArray:
+									return existingValue;
+								default: {
+										count++;
+										if (count > 1)
+											throw new JsonSerializationException(string.Format("Too many objects at path {0}.", reader.Path));
+										existingValue = existingValue ?? contract.DefaultCreator();
+										serializer.Populate(reader, existingValue);
+									}
+									break;
+							}
+						}
+						// Should not come here.
+						throw new JsonSerializationException(string.Format("Unclosed array at path {0}.", reader.Path));
+					}
+
+				case JsonToken.Null:
+					return null;
+
+				case JsonToken.StartObject:
+					existingValue = existingValue ?? contract.DefaultCreator();
+					serializer.Populate(reader, existingValue);
+					return existingValue;
+
+				default:
+					throw new InvalidOperationException("Unexpected token type " + reader.TokenType.ToString());
+			}
+		}
+
+		public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) {
+			throw new NotImplementedException();
+		}
+	}
+
+	public static partial class JsonExtensions {
+		public static JsonReader SkipComments(this JsonReader reader) {
+			while (reader.TokenType == JsonToken.Comment && reader.Read())
+				;
+			return reader;
+		}
+	}
+}

Jugenddienst Stunden/ViewModels/StundenViewModel.cs

@@ -34,6 +34,11 @@ namespace Jugenddienst_Stunden.ViewModels {
 		public string OvertimeMonth {
 			get => _hour.overtime_month;
 		}
+		
+		public Dictionary<int, decimal> ZeitTotalDaily {
+			get => _hour.zeit_total_daily;
+		}
+
 		public string Title { get; set; } = Preferences.Default.Get("name", "") + " " + Preferences.Default.Get("surname", "");
 
 		public StundenViewModel() {
@@ -46,7 +51,7 @@ namespace Jugenddienst_Stunden.ViewModels {
 
 		public async Task LoadData() {
 			_hour = await Models.Stunde.LoadData();
-			Models.Hours Hours = new Models.Hours();
+			//Models.Hours Hours = new Models.Hours();
 			//Title = _hour.operator_api.name + " " + _hour.operator_api.surname;
 			RefreshProperties();
 		}
@@ -59,6 +64,7 @@ namespace Jugenddienst_Stunden.ViewModels {
 			OnPropertyChanged(nameof(ZeitDone));
 			OnPropertyChanged(nameof(Hours));
 			OnPropertyChanged(nameof(Title));
+			OnPropertyChanged(nameof(ZeitTotalDaily));
 		}