使用 C# 9 的records作为强类型ID - JSON序列化-白红宇的个人博客

发布日期：2021-05-09 05:28:40 浏览次数：17 分类：博客文章

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��ID�� JSON ��

{    "id": {        "value": 1    },    "name": "Apple",    "unitPrice": 0.8}

��ID��record��

System.Text.Json

��ASP.NET Core��3.0��JSON��System.Text.Json��

��id�� JsonConverter��

public class StronglyTypedIdJsonConverter
   
     : JsonConverter
    
         where TStronglyTypedId : StronglyTypedId
     
          where TValue : notnull{    public override TStronglyTypedId Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)    {        if (reader.TokenType is JsonTokenType.Null)            return null;        var value = JsonSerializer.Deserialize
      
       (ref reader, options);        var factory = StronglyTypedIdHelper.GetFactory
       
        (typeToConvert);        return (TStronglyTypedId)factory(value);    }    public override void Write(Utf8JsonWriter writer, TStronglyTypedId value, JsonSerializerOptions options)    {        if (value is null)            writer.WriteNullValue();        else            JsonSerializer.Serialize(writer, value.Value, options);    }}

�� id.value, ��id��

��:

services.AddControllers()    .AddJsonOptions(options =>    {        options.JsonSerializerOptions.Converters.Add(            new StronglyTypedIdJsonConverter
   
    ());    });

��

{    "id": 1,    "name": "Apple",    "unitPrice": 0.8}

��ProductId��ID��id��(ConverterFactory),��

public class StronglyTypedIdJsonConverterFactory : JsonConverterFactory{    private static readonly ConcurrentDictionary
   
     Cache = new();    public override bool CanConvert(Type typeToConvert)    {        return StronglyTypedIdHelper.IsStronglyTypedId(typeToConvert);    }    public override JsonConverter CreateConverter(Type typeToConvert, JsonSerializerOptions options)    {        return Cache.GetOrAdd(typeToConvert, CreateConverter);    }    private static JsonConverter CreateConverter(Type typeToConvert)    {        if (!StronglyTypedIdHelper.IsStronglyTypedId(typeToConvert, out var valueType))            throw new InvalidOperationException($"Cannot create converter for '{typeToConvert}'");        var type = typeof(StronglyTypedIdJsonConverter<,>).MakeGenericType(typeToConvert, valueType);        return (JsonConverter)Activator.CreateInstance(type);    }}

��id��

��JsonConvert��Factory��ID

services.AddControllers()    .AddJsonOptions(options =>    {        options.JsonSerializerOptions.Converters.Add(            new StronglyTypedIdJsonConverterFactory());    });

Newtonsoft.Json

��Newtonsoft.Json��JSON��

��Newtonsoft.Json ��compatible JsonConverter��TypeConverter, ��TypeConverter��string��, �� TypeConverter��Newtonsoft.Json��

{    "id": "1",    "name": "Apple",    "unitPrice": 0.8}

��id��id��GUID��int��

�� System.Text.Json ��Newtonsoft.Json��ConvertFactory��

public class StronglyTypedIdNewtonsoftJsonConverter : JsonConverter{    private static readonly ConcurrentDictionary
   
     Cache = new();    public override bool CanConvert(Type objectType)    {        return StronglyTypedIdHelper.IsStronglyTypedId(objectType);    }    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)    {        var converter = GetConverter(objectType);        return converter.ReadJson(reader, objectType, existingValue, serializer);    }    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)    {        if (value is null)        {            writer.WriteNull();        }        else        {            var converter = GetConverter(value.GetType());            converter.WriteJson(writer, value, serializer);        }    }    private static JsonConverter GetConverter(Type objectType)    {        return Cache.GetOrAdd(objectType, CreateConverter);    }    private static JsonConverter CreateConverter(Type objectType)    {        if (!StronglyTypedIdHelper.IsStronglyTypedId(objectType, out var valueType))            throw new InvalidOperationException($"Cannot create converter for '{objectType}'");        var type = typeof(StronglyTypedIdNewtonsoftJsonConverter<,>).MakeGenericType(objectType, valueType);        return (JsonConverter)Activator.CreateInstance(type);    }}public class StronglyTypedIdNewtonsoftJsonConverter
    
      : JsonConverter
     
          where TStronglyTypedId : StronglyTypedId
      
           where TValue : notnull{    public override TStronglyTypedId ReadJson(JsonReader reader, Type objectType, TStronglyTypedId existingValue, bool hasExistingValue, JsonSerializer serializer)    {        if (reader.TokenType is JsonToken.Null)            return null;        var value = serializer.Deserialize
       
        (reader);        var factory = StronglyTypedIdHelper.GetFactory
        
         (objectType); return (TStronglyTypedId)factory(value); } public override void WriteJson(JsonWriter writer, TStronglyTypedId value, JsonSerializer serializer) { if (value is null) writer.WriteNull(); else writer.WriteValue(value.Value); }}

��

services.AddControllers()        .AddNewtonsoftJson(options =>        {            options.SerializerSettings.Converters.Add(                new StronglyTypedIdNewtonsoftJsonConverter());        });

��

{    "id": 1,    "name": "Apple",    "unitPrice": 0.8}

��: thomas levesque
��

��

�� QQ�� 897216102

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