[C#] support Json Serialization (#5752)

* support json serialization

* fix invalid json format.
* string must be written with double quotes.
* remove commma after the last object member.

* fix indent

* Revert "fix invalid json format."

This reverts commit d6820ed50c.

* quated string value.

* add cs-gen-json-serializer flag.

* fix preprocessor indent

* ENABLE_JSON_SERIALIZATION -> ENABLE_JSON_SERIALIZATION_TEST

* share TestBuffer method

* remove ENABLE_JSON_SERIALIZATION

* remove duplicated test data

* [windows] add nuget restore and copy test data.

* [docker mono] share msbuild settings with windows. add nuget restore and copy test data.

* add some note for json api.

tests/union_vector/Attacker.cs

@@ -50,6 +50,7 @@ public struct Attacker : IFlatbufferObject
 
 public class AttackerT
 {
+  [Newtonsoft.Json.JsonProperty("sword_attack_damage")]
   public int SwordAttackDamage { get; set; }
 
   public AttackerT() {

tests/union_vector/BookReader.cs

@@ -39,6 +39,7 @@ public struct BookReader : IFlatbufferObject
 
 public class BookReaderT
 {
+  [Newtonsoft.Json.JsonProperty("books_read")]
   public int BooksRead { get; set; }
 
   public BookReaderT() {

tests/union_vector/Character.cs

@@ -2,6 +2,7 @@
 //  automatically generated by the FlatBuffers compiler, do not modify
 // </auto-generated>
 
+[Newtonsoft.Json.JsonConverter(typeof(Newtonsoft.Json.Converters.StringEnumConverter))]
 public enum Character : byte
 {
   NONE = 0,
@@ -43,3 +44,49 @@ public class CharacterUnion {
   }
 }
 
+public class CharacterUnion_JsonConverter : Newtonsoft.Json.JsonConverter {
+  public override bool CanConvert(System.Type objectType) {
+    return objectType == typeof(CharacterUnion) || objectType == typeof(System.Collections.Generic.List<CharacterUnion>);
+  }
+  public override void WriteJson(Newtonsoft.Json.JsonWriter writer, object value, Newtonsoft.Json.JsonSerializer serializer) {
+    var _olist = value as System.Collections.Generic.List<CharacterUnion>;
+    if (_olist != null) {
+      writer.WriteStartArray();
+      foreach (var _o in _olist) { this.WriteJson(writer, _o, serializer); }
+      writer.WriteEndArray();
+    } else {
+      this.WriteJson(writer, value as CharacterUnion, serializer);
+    }
+  }
+  public void WriteJson(Newtonsoft.Json.JsonWriter writer, CharacterUnion _o, Newtonsoft.Json.JsonSerializer serializer) {
+    if (_o == null) return;
+    serializer.Serialize(writer, _o.Value);
+  }
+  public override object ReadJson(Newtonsoft.Json.JsonReader reader, System.Type objectType, object existingValue, Newtonsoft.Json.JsonSerializer serializer) {
+    var _olist = existingValue as System.Collections.Generic.List<CharacterUnion>;
+    if (_olist != null) {
+      for (var _j = 0; _j < _olist.Count; ++_j) {
+        reader.Read();
+        _olist[_j] = this.ReadJson(reader, _olist[_j], serializer);
+      }
+      reader.Read();
+      return _olist;
+    } else {
+      return this.ReadJson(reader, existingValue as CharacterUnion, serializer);
+    }
+  }
+  public CharacterUnion ReadJson(Newtonsoft.Json.JsonReader reader, CharacterUnion _o, Newtonsoft.Json.JsonSerializer serializer) {
+    if (_o == null) return null;
+    switch (_o.Type) {
+      default: break;
+      case Character.MuLan: _o.Value = serializer.Deserialize<AttackerT>(reader); break;
+      case Character.Rapunzel: _o.Value = serializer.Deserialize<RapunzelT>(reader); break;
+      case Character.Belle: _o.Value = serializer.Deserialize<BookReaderT>(reader); break;
+      case Character.BookFan: _o.Value = serializer.Deserialize<BookReaderT>(reader); break;
+      case Character.Other: _o.Value = serializer.Deserialize<string>(reader); break;
+      case Character.Unused: _o.Value = serializer.Deserialize<string>(reader); break;
+    }
+    return _o;
+  }
+}
+

tests/union_vector/Movie.cs

@@ -146,12 +146,50 @@ public struct Movie : IFlatbufferObject
 
 public class MovieT
 {
+  [Newtonsoft.Json.JsonProperty("main_character_type")]
+  private Character MainCharacterType {
+    get {
+      return this.MainCharacter != null ? this.MainCharacter.Type : Character.NONE;
+    }
+    set {
+      this.MainCharacter = new CharacterUnion();
+      this.MainCharacter.Type = value;
+    }
+  }
+  [Newtonsoft.Json.JsonProperty("main_character")]
+  [Newtonsoft.Json.JsonConverter(typeof(CharacterUnion_JsonConverter))]
   public CharacterUnion MainCharacter { get; set; }
+  [Newtonsoft.Json.JsonProperty("characters_type")]
+  private Character[] CharactersType {
+    get {
+      if (this.Characters == null) return null;
+      var _o = new Character[this.Characters.Count];
+      for (var _j = 0; _j < _o.Length; ++_j) { _o[_j] = this.Characters[_j].Type; }
+      return _o;
+    }
+    set {
+      this.Characters = new List<CharacterUnion>();
+      for (var _j = 0; _j < value.Length; ++_j) {
+        var _o = new CharacterUnion();
+        _o.Type = value[_j];
+        this.Characters.Add(_o);
+      }
+    }
+  }
+  [Newtonsoft.Json.JsonProperty("characters")]
+  [Newtonsoft.Json.JsonConverter(typeof(CharacterUnion_JsonConverter))]
   public List<CharacterUnion> Characters { get; set; }
 
   public MovieT() {
     this.MainCharacter = null;
     this.Characters = null;
   }
+
+  public static MovieT DeserializeFromJson(string jsonText) {
+    return Newtonsoft.Json.JsonConvert.DeserializeObject<MovieT>(jsonText);
+  }
+  public string SerializeToJson() {
+    return Newtonsoft.Json.JsonConvert.SerializeObject(this, Newtonsoft.Json.Formatting.Indented);
+  }
 }
 

tests/union_vector/Rapunzel.cs

@@ -39,6 +39,7 @@ public struct Rapunzel : IFlatbufferObject
 
 public class RapunzelT
 {
+  [Newtonsoft.Json.JsonProperty("hair_length")]
   public int HairLength { get; set; }
 
   public RapunzelT() {