{"id":834,"date":"2024-11-03T17:57:27","date_gmt":"2024-11-04T01:57:27","guid":{"rendered":"https:\/\/devblogs.microsoft.com\/dotnet-ch\/?p=834"},"modified":"2024-11-03T17:57:27","modified_gmt":"2024-11-04T01:57:27","slug":"net-9-%e4%b8%adsystem-text-json-%e7%9a%84%e6%96%b0%e5%a2%9e%e5%8a%9f%e8%83%bd","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/dotnet-ch\/net-9-%e4%b8%adsystem-text-json-%e7%9a%84%e6%96%b0%e5%a2%9e%e5%8a%9f%e8%83%bd\/","title":{"rendered":".NET 9 \u4e2dSystem.Text.Json \u7684\u65b0\u589e\u529f\u80fd\u00a0"},"content":{"rendered":"

\u672c\u7bc7\u7ffb\u8bd1\u4e8eEirik Tsarpalis\u7684\u00a0What’s new in System.Text.Json in .NET 9 – .NET Blog<\/a>\u00a0<\/em><\/p>\n

System.Text.Json<\/span>\u7684<\/span>9.0 <\/span>\u7248\u672c\u5305\u542b\u8bb8\u591a\u529f\u80fd\uff0c\u4e3b\u8981\u4fa7\u91cd\u4e8e<\/span> JSON <\/span>\u67b6\u6784\u548c\u667a\u80fd\u5e94\u7528\u7a0b\u5e8f\u652f\u6301\u3002\u5b83\u8fd8\u5305\u62ec\u4e00\u4e9b\u5907\u53d7\u671f\u5f85\u7684\u589e\u5f3a\u529f\u80fd\uff0c\u4f8b\u5982\u53ef\u7a7a\u5f15\u7528\u7c7b\u578b\u652f\u6301\u3001\u81ea\u5b9a\u4e49\u679a\u4e3e\u6210\u5458\u540d\u79f0\u3001\u65e0\u5e8f\u5143\u6570\u636e\u53cd\u5e8f\u5217\u5316\u548c\u81ea\u5b9a\u4e49\u5e8f\u5217\u5316\u7f29\u8fdb<\/span>\u3002<\/span>\u00a0<\/span><\/p>\n

\u83b7\u53d6\u6700\u65b0\u4fe1\u606f<\/span><\/b>\u00a0<\/span><\/h3>\n

\u60a8\u53ef\u4ee5\u901a\u8fc7\u5f15\u7528<\/span> System.Text.Json NuGet <\/span>\u5305<\/span><\/a>\u7684\u6700\u65b0\u7248\u672c\u6216<\/span> .NET 9 <\/span>\u7684\u6700\u65b0<\/span> SDK<\/span><\/a> \u6765\u5c1d\u8bd5\u65b0\u529f\u80fd<\/span>\u3002<\/span>\u00a0<\/span><\/p>\n

JSON <\/span><\/b>\u67b6\u6784\u5bfc\u51fa\u5668<\/span><\/b>\u00a0<\/span><\/h2>\n

\u65b0\u7684<\/span> JsonSchemaExporter <\/span>\u7c7b\u53ef\u4ee5\u4f7f\u7528<\/span> JsonSerializerOptions <\/span>\u6216<\/span> JsonTypeInfo <\/span>\u5b9e\u4f8b\u4ece<\/span> .NET <\/span>\u7c7b\u578b\u4e2d\u63d0\u53d6<\/span> JSON <\/span>\u67b6\u6784<\/span><\/a>\u6587\u6863<\/span>\uff1a<\/span>\u00a0<\/span><\/p>\n

using System.Text.Json.Schema;\r\n\r\nJsonSerializerOptions options = JsonSerializerOptions.Default;\r\nJsonNode schema = options.GetJsonSchemaAsNode(typeof(Person));\r\nConsole.WriteLine(schema.ToString());\r\n\/\/{\r\n\/\/  \"type\": [\"object\", \"null\"],\r\n\/\/  \"properties\": {\r\n\/\/    \"Name\": { \"type\": \"string\" },\r\n\/\/    \"Age\": { \"type\": \"integer\" },\r\n\/\/    \"Address\": { \"type\": [\"string\", \"null\"], \"default\": null }\r\n\/\/  },\r\n\/\/  \"required\": [\"Name\", \"Age\"]\r\n\/\/}\r\n\r\nrecord Person(string Name, int Age, string? Address = null);<\/code><\/pre>\n
\u751f\u6210\u7684\u6a21\u5f0f\u4e3a\u8be5\u7c7b\u578b\u63d0\u4f9b\u4e86<\/span>JSON<\/span>\u5e8f\u5217\u5316\u5951\u7ea6\u7684\u89c4\u8303\u3002\u4ece\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\u53ef\u4ee5\u770b\u51fa\uff0c\u5b83\u533a\u5206\u4e86\u53ef\u7a7a\u5c5e\u6027\u548c\u4e0d\u53ef\u7a7a\u5c5e\u6027\uff0c\u5e76\u6839\u636e\u6784\u9020\u51fd\u6570\u53c2\u6570\u662f\u5426\u53ef\u9009\u6765\u586b\u5145<\/span>\u201crequired\u201d<\/span>\u5173\u952e\u5b57\u3002\u6a21\u5f0f\u7684\u8f93\u51fa\u53ef\u4ee5\u901a\u8fc7\u5728<\/span> JsonSerializerOptions <\/span>\u6216<\/span> JsonTypeInfo <\/span>\u5b9e\u4f8b\u4e2d\u6307\u5b9a\u7684\u914d\u7f6e\u8fdb\u884c\u5f71\u54cd<\/span>:<\/span>\u00a0<\/span><\/p>\n
JsonSerializerOptions options = new(JsonSerializerOptions.Default)\r\n{\r\n    PropertyNamingPolicy = JsonNamingPolicy.KebabCaseUpper,\r\n    NumberHandling = JsonNumberHandling.WriteAsString,\r\n    UnmappedMemberHandling = JsonUnmappedMemberHandling.Disallow,\r\n};\r\n\r\nJsonNode schema = options.GetJsonSchemaAsNode(typeof(MyPoco));\r\nConsole.WriteLine(schema.ToString());\r\n\/\/{\r\n\/\/  \"type\": [\"object\", \"null\"],\r\n\/\/  \"properties\": {\r\n\/\/    \"NUMERIC-VALUE\": {\r\n\/\/      \"type\": [\"string\", \"integer\"],\r\n\/\/      \"pattern\": \"^-?(?:0|[1-9]\\\\d*)$\"\r\n\/\/    }\r\n\/\/  },\r\n\/\/  \"additionalProperties\": false\r\n\/\/}\r\n\r\nclass MyPoco\r\n{\r\n    public int NumericValue { get; init; }\r\n}<\/code><\/pre>\n
\u7528\u6237\u53ef\u4ee5\u4f7f\u7528<\/span> JsonSchemaExporterOptions <\/span>\u914d\u7f6e\u7c7b\u578b\u8fdb\u4e00\u6b65\u63a7\u5236\u751f\u6210\u7684\u6a21\u5f0f\uff1a<\/span>\u00a0<\/span><\/p>\n
JsonSerializerOptions options = JsonSerializerOptions.Default;\r\nJsonSchemaExporterOptions exporterOptions = new()\r\n{\r\n    \/\/ Marks root-level types as non-nullable\r\n    TreatNullObliviousAsNonNullable = true,\r\n};\r\n\r\nJsonNode schema = options.GetJsonSchemaAsNode(typeof(Person), exporterOptions);\r\nConsole.WriteLine(schema.ToString());\r\n\/\/{\r\n\/\/  \"type\": \"object\",\r\n\/\/  \"properties\": {\r\n\/\/    \"Name\": { \"type\": \"string\" }\r\n\/\/  },\r\n\/\/  \"required\": [\"Name\"]\r\n\/\/}\r\n\r\nrecord Person(string Name);<\/code><\/pre>\n
\u6700\u540e\uff0c\u7528\u6237\u53ef\u4ee5\u901a\u8fc7\u6307\u5b9a<\/span> TransformSchemaNode <\/span>\u59d4\u6258<\/span>,<\/span> \u5bf9\u751f\u6210\u7684\u67b6\u6784\u8282\u70b9\u5e94\u7528\u81ea\u5df1\u7684\u8f6c\u6362\u3002\u4ee5\u4e0b\u662f\u5305\u542b\u6765\u81ea<\/span> DescriptionAttribute <\/span>\u6ce8\u91ca\u7684\u6587\u672c\u7684\u793a\u4f8b<\/span>\uff1a<\/span>\u00a0<\/span><\/p>\n
JsonSchemaExporterOptions exporterOptions = new()\r\n{\r\n    TransformSchemaNode = (context, schema) =>\r\n    {\r\n        \/\/ Determine if a type or property and extract the relevant attribute provider\r\n        ICustomAttributeProvider? attributeProvider = context.PropertyInfo is not null\r\n            ? context.PropertyInfo.AttributeProvider\r\n            : context.TypeInfo.Type;\r\n\r\n        \/\/ Look up any description attributes\r\n        DescriptionAttribute? descriptionAttr = attributeProvider?\r\n            .GetCustomAttributes(inherit: true)\r\n            .Select(attr => attr as DescriptionAttribute)\r\n            .FirstOrDefault(attr => attr is not null);\r\n\r\n        \/\/ Apply description attribute to the generated schema\r\n        if (descriptionAttr != null)\r\n        {\r\n            if (schema is not JsonObject jObj)\r\n            {\r\n                \/\/ Handle the case where the schema is a boolean\r\n                JsonValueKind valueKind = schema.GetValueKind();\r\n                Debug.Assert(valueKind is JsonValueKind.True or JsonValueKind.False);\r\n                schema = jObj = new JsonObject();\r\n                if (valueKind is JsonValueKind.False)\r\n                {\r\n                    jObj.Add(\"not\", true);\r\n                }\r\n            }\r\n\r\n            jObj.Insert(0, \"description\", descriptionAttr.Description);\r\n        }\r\n\r\n        return schema;\r\n    }\r\n};<\/code><\/pre>\n
\u7efc\u5408\u4ee5\u4e0a\u5185\u5bb9\uff0c\u6211\u4eec\u73b0\u5728\u53ef\u4ee5\u751f\u6210\u4e00\u4e2a\u5305\u542b\u6765\u81ea\u5c5e\u6027\u6ce8\u91ca\u7684<\/span>description<\/span>\u5173\u952e\u5b57\u6e90\u7684\u6a21\u5f0f<\/span>\uff1a<\/span>\u00a0<\/span><\/p>\n
JsonNode schema = options.GetJsonSchemaAsNode(typeof(Person), exporterOptions);\r\nConsole.WriteLine(schema.ToString());\r\n\/\/{\r\n\/\/  \"description\": \"A person\",\r\n\/\/  \"type\": [\"object\", \"null\"],\r\n\/\/  \"properties\": {\r\n\/\/    \"Name\": { \"description\": \"The name of the person\", \"type\": \"string\" }\r\n\/\/  },\r\n\/\/  \"required\": [\"Name\"]\r\n\/\/}\r\n\r\n[Description(\"A person\")]\r\nrecord Person([property: Description(\"The name of the person\")] string Name);<\/code><\/pre>\n
\u5728\u4e3a<\/span> .NET <\/span>\u65b9\u6cd5\u6216<\/span> API <\/span>\u751f\u6210\u67b6\u6784\u65f6\uff0c\u8fd9\u662f\u4e00\u4e2a\u7279\u522b\u6709\u7528\u7684\u7ec4\u4ef6\uff1b\u5b83\u88ab\u7528\u4e8e\u652f\u6301<\/span> ASP.NET Core <\/span>\u6700\u65b0\u53d1\u5e03\u7684<\/span> OpenAPI <\/span>\u7ec4\u4ef6\uff0c\u5e76\u4e14\u6211\u4eec\u5df2\u5c06\u5176\u90e8\u7f72\u5230\u8bb8\u591a\u5177\u6709\u5de5\u5177\u8c03\u7528\u8981\u6c42\u7684<\/span> AI <\/span>\u76f8\u5173\u5e93\u548c\u5e94\u7528\u7a0b\u5e8f\u4e2d\uff0c\u4f8b\u5982<\/span> Semantic Kernel\u3001Visual Studio Copilot <\/span>\u548c\u6700\u65b0\u53d1\u5e03\u7684<\/span> Microsoft.Extensions.AI <\/span>\u5e93<\/span>\u3002<\/span>\u00a0<\/span><\/p>\n
\u6d41\u5f0f\u5904\u7406\u591a\u4e2a<\/span><\/b> JSON <\/span><\/b>\u6587\u6863<\/span><\/b>\u00a0<\/span><\/h2>\n
Utf8JsonReader <\/span>\u73b0\u5728\u652f\u6301\u4ece\u5355\u4e2a\u7f13\u51b2\u533a\u6216\u6d41\u4e2d\u8bfb\u53d6\u591a\u4e2a\u4ee5\u7a7a\u683c\u5206\u9694\u7684<\/span> JSON <\/span>\u6587\u6863\u3002\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0c\u5982\u679c<\/span> Utf8JsonReader <\/span>\u68c0\u6d4b\u5230\u7b2c\u4e00\u4e2a\u9876\u7ea7\u6587\u6863\u540e\u9762\u6709\u4efb\u4f55\u975e\u7a7a\u683c\u5b57\u7b26\uff0c\u5b83\u5c06\u629b\u51fa<\/span> \u5f02\u5e38\u3002\u8fd9\u53ef\u4ee5\u4f7f\u7528<\/span> JsonReaderOptions.AllowMultipleValues <\/span>\u6807\u5fd7\u6765\u6539\u53d8<\/span>\uff1a<\/span>\u00a0<\/span><\/p>\n
JsonReaderOptions options = new() { AllowMultipleValues = true };\r\nUtf8JsonReader reader = new(\"null {} 1 \\r\\n [1,2,3]\"u8, options);\r\n\r\nreader.Read();\r\nConsole.WriteLine(reader.TokenType); \/\/ Null\r\n\r\nreader.Read();\r\nConsole.WriteLine(reader.TokenType); \/\/ StartObject\r\nreader.Skip();\r\n\r\nreader.Read();\r\nConsole.WriteLine(reader.TokenType); \/\/ Number\r\n\r\nreader.Read();\r\nConsole.WriteLine(reader.TokenType); \/\/ StartArray\r\nreader.Skip();\r\n\r\nConsole.WriteLine(reader.Read()); \/\/ False<\/code><\/pre>\n
\u6b64\u5916\uff0c\u8fd9\u8fd8\u4f7f\u5f97\u4ece\u53ef\u80fd\u5305\u542b\u65e0\u6548<\/span> JSON <\/span>\u5c3e\u90e8\u6570\u636e\u7684\u6709\u6548\u8d1f\u8f7d\u4e2d\u8bfb\u53d6<\/span> JSON <\/span>\u6210\u4e3a\u53ef\u80fd<\/span>\uff1a<\/span>\u00a0<\/span><\/p>\n
Utf8JsonReader reader = new(\"[1,2,3]    <NotJson\/>\"u8, new() { AllowMultipleValues = true });\r\n\r\nreader.Read();\r\nreader.Skip(); \/\/ Success\r\nreader.Read(); \/\/ throws JsonReaderException<\/code><\/pre>\n
\u5728\u6d41\u5f0f\u53cd\u5e8f\u5217\u5316\u65b9\u9762\uff0c\u6211\u4eec\u6dfb\u52a0\u4e86\u65b0\u7684<\/span> JsonSerializer.DeserializeAsyncEnumerable <\/span>\u91cd\u8f7d\uff0c\u4f7f\u6d41\u5f0f\u5904\u7406\u591a\u4e2a\u9876\u7ea7\u503c\u6210\u4e3a\u53ef\u80fd\u3002\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0c<\/span>DeserializeAsyncEnumerable <\/span>\u5c06\u5c1d\u8bd5\u6d41\u5f0f\u5904\u7406\u9876\u7ea7<\/span> JSON <\/span>\u6570\u7ec4\u4e2d\u5305\u542b\u7684\u5143\u7d20\u3002\u8fd9\u53ef\u4ee5\u4f7f\u7528\u65b0\u7684<\/span> topLevelValues <\/span>\u6807\u5fd7\u5207\u6362<\/span>\uff1a<\/span>\u00a0<\/span><\/p>\n
ReadOnlySpan<byte> utf8Json = \"\"\"[0] [0,1] [0,1,1] [0,1,1,2] [0,1,1,2,3]\"\"\"u8;\r\nusing var stream = new MemoryStream(utf8Json.ToArray());\r\n\r\nawait foreach (int[] item in JsonSerializer.DeserializeAsyncEnumerable<int[]>(stream, topLevelValues: true))\r\n{\r\n    Console.WriteLine(item.Length);\r\n}<\/code><\/pre>\n
\u9075\u5faa\u53ef<\/span><\/b>null<\/span><\/b>\u6ce8\u91ca<\/span><\/b>\u00a0<\/span><\/h2>\n
JsonSerializer <\/span>\u73b0\u5728\u4e3a\u5e8f\u5217\u5316\u548c\u53cd\u5e8f\u5217\u5316\u4e2d\u7684\u975e\u7a7a\u5f15\u7528\u7c7b\u578b\u5f3a\u5236\u589e\u52a0\u4e86\u6709\u9650\u7684\u652f\u6301\u3002\u8fd9\u53ef\u4ee5\u4f7f\u7528<\/span> RespectNullableAnnotations <\/span>\u6807\u5fd7\u8fdb\u884c\u5207\u6362<\/span>\uff1a<\/span>\u00a0<\/span><\/code><\/p>\n
#nullable enable\r\nJsonSerializerOptions options = new() { RespectNullableAnnotations = true };\r\n\r\nMyPoco invalidValue = new(Name: null!);\r\nJsonSerializer.Serialize(invalidValue, options);\r\n\/\/ System.Text.Json.JsonException: The property or field 'Name'\r\n\/\/ on type 'MyPoco' doesn't allow getting null values. Consider\r\n\/\/ updating its nullability annotation. \r\n\r\nrecord MyPoco(string Name);<\/code>\r\n<\/code><\/pre>\n
JsonSerializerOptions options = new() { RespectNullableAnnotations = true };\r\nstring json = \"\"\"{\"Name\":null}\"\"\";\r\nJsonSerializer.Deserialize<MyPoco>(json, options);\r\n\/\/ System.Text.Json.JsonException: The constructor parameter 'Name'\r\n\/\/ on type 'MyPoco' doesn't allow null values. Consider updating\r\n\/\/ its nullability annotation.<\/code><\/pre>\n
\u9650\u5236<\/span><\/b>\u00a0<\/span><\/h3>\n
\u7531\u4e8e\u975e\u7a7a\u5f15\u7528\u7c7b\u578b\u7684\u5b9e\u73b0\u65b9\u5f0f\uff0c\u6b64\u529f\u80fd\u5e26\u6709\u4e00\u4e9b\u91cd\u8981\u7684\u9650\u5236\uff0c\u7528\u6237\u5728\u542f\u7528\u4e4b\u524d\u9700\u8981\u719f\u6089\u8fd9\u4e9b\u9650\u5236\u3002\u95ee\u9898\u7684\u6839\u6e90\u5728\u4e8e\u5f15\u7528\u7c7b\u578b\u53ef\u7a7a\u6027\u5728<\/span> IL <\/span>\u4e2d\u6ca1\u6709\u4e00\u6d41\u7684\u8868\u793a\u5f62\u5f0f<\/span>\uff0c<\/span>\u4f8b\u5982\u4ece\u8fd0\u884c\u65f6\u53cd\u5c04\u7684\u89d2\u5ea6\u6765\u770b\uff0c\u8868\u8fbe\u5f0f<\/span> MyPoco <\/span>\u548c<\/span> MyPoco? <\/span>\u662f<\/span>\u65e0\u6cd5\u533a\u5206\u7684<\/span><\/a>\u3002\u867d\u7136\u7f16\u8bd1\u5668\u4f1a\u5c3d<\/span>\u53ef\u80fd\u901a\u8fc7<\/span>\u53d1\u51fa\u5c5e\u6027\u5143\u6570\u636e<\/span><\/a>\u6765\u5f25\u8865\u8fd9\u4e00\u70b9\uff0c\u4f46\u8fd9\u4ec5\u9650\u4e8e\u7279\u5b9a\u7c7b\u578b\u5b9a\u4e49\u8303\u56f4\u5185\u7684\u975e\u6cdb\u578b\u6210\u5458\u6ce8\u89e3\u3002\u6b63\u662f\u51fa\u4e8e\u8fd9\u4e2a\u539f\u56e0\uff0c\u8be5\u6807\u5fd7\u4ec5\u9a8c\u8bc1\u975e\u6cdb\u578b\u5c5e\u6027\u3001\u5b57\u6bb5\u548c\u6784\u9020\u51fd\u6570\u53c2\u6570\u4e0a\u5b58\u5728\u7684\u53ef\u7a7a\u6027\u6ce8\u91ca\u3002<\/span>System.Text.Json <\/span>\u4e0d\u652f\u6301\u5bf9<\/span>\u00a0<\/span><\/p>\n