Simple tool for making dart source code out of JSON files. (depends on Newtonsoft.Json and Humanizer)

Json2Dart.cs

using System;
using System.IO;
using System.Linq;
using System.Text;
using Humanizer;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace Json2Dart
{
	public static class Program
	{
		public static void Main(string[] args)
		{
			var outputMode = args.Contains("--output") || args.Contains("-o");
			
			const string inputFilePath = "input.json";
			const string outputFilePath = "output.dart";

			while (true)
			{
				Console.Write("Enter class name: ");
				var className = Console.ReadLine();

				// Console.Clear();
				// Console.WriteLine("Enter JSON (press Alt+Enter to return):");
				// var json = ReadLines();
				
				if (!File.Exists(inputFilePath))
				{
					Console.WriteLine("Couldn't find input file");
					Environment.Exit(1);
				}

				var json = File.ReadAllText(inputFilePath);
				var jObject = GetJObject(json);
				
				Console.WriteLine("Converting...");
				var dart = ToDart(jObject, className);

				if (outputMode)
				{
					File.WriteAllText(outputFilePath, dart);
					return;
				}

				Console.WriteLine("===== copy here~");
				Console.WriteLine(dart);

				Console.ReadLine();
			}
		}

		private static JObject GetJObject(string json)
		{

			Console.WriteLine("Deserializing...");
			var serializerSettings = new JsonSerializerSettings()
			{
				NullValueHandling = NullValueHandling.Ignore,
			};
			
			var jObject = (JObject) JsonConvert.DeserializeObject(json, serializerSettings);
			return jObject;
		}

		private static string ToDart(JObject jObject, string className)
		{
			var stringBuilder = new StringBuilder();

			stringBuilder.AppendLine($"class {className} {{");
			
			foreach (var pair in jObject)
			{
				var key = pair.Key.Camelize();
				var dartType = ToDartType(pair.Value);
				var supported = IsJsonTypeSupported(pair.Value.Type);

				AppendLine(stringBuilder, $"{dartType} {key};", 1, !supported);
			}

			stringBuilder.AppendLine();
			
			AppendLine(stringBuilder, $"{className}.fromJson(Map<String, dynamic> json) {{", 1);
			
			foreach (var pair in jObject)
			{
				var key = pair.Key.Camelize();
				var supported = IsJsonTypeSupported(pair.Value.Type);
				
				AppendLine(stringBuilder, $"{key} = json[\"{pair.Key}\"];", 2, !supported);
			}

			AppendLine(stringBuilder, "}", 1);
			
			AppendLine(stringBuilder, "}");
			
			return stringBuilder.ToString();
		}

		private static void AppendLine(StringBuilder sb, string value, int indent = 0, bool comment = false)
		{
			if (comment)
				sb.Append("//");
			
			sb.Append('\t', indent);
			sb.AppendLine(value);
		}

		private static string ToDartType(JToken token)
		{
			return token.Type switch
			{
				JTokenType.Integer   => "int",
				JTokenType.Float     => "float",
				JTokenType.String    => "String",
				JTokenType.Boolean   => "bool",
				JTokenType.Array     => $"List<{(token.HasValues ? ToDartType(token.Values().First()) : "dynamic")}>",
				_				     => "dynamic"
			};
		}

		private static bool IsJsonTypeSupported(JTokenType type)
		{
			var supportedTokenTypes = new[]
			{
				JTokenType.Integer,
				JTokenType.Float,
				JTokenType.String,
				JTokenType.Boolean,
			};
			
			return supportedTokenTypes.Contains(type);
		}

		[Obsolete("Seems to skip characters, therefore unreliable.")]
		private static string ReadLines()
		{
			var stringBuilder = new StringBuilder();
			
			while (true)
			{
				var key = Console.ReadKey(true);

				if (key.Modifiers == ConsoleModifiers.Alt && key.Key == ConsoleKey.Enter)
					break;
				
				if (key.Key == ConsoleKey.Backspace)
				{
					stringBuilder.Remove(stringBuilder.Length - 1, 1);
					Console.CursorLeft--;
					continue;
				}
				
				stringBuilder.Append(key.KeyChar);
				Console.Write(key.KeyChar);
			}

			return stringBuilder.ToString();
		}
	}
}