在.NET Core 3中序列化Manatee.Json [英] Serializing Manatee.Json in .NET Core 3
问题描述
背景
我想从我的.NET Core 3应用程序中提供一些JsonSchema，以及序列化为JSON的其他对象.由于Manatee.Json经常更新并为JsonSchema提供良好的支持，因此它们是我的首选.同时，.NET Core 3为使用魔术返回对象(将对象转换为JSON文档)提供了出色的支持.
Background
I want to provide some JsonSchema from my .NET Core 3 application, as well as other objects serialized into JSON. Since Manatee.Json is frequently updated and provides good support for JsonSchema, they are my preferred choice. At the same time, .NET Core 3 provides excellent support for returning objects with magic that transform them into JSON documents.
示例:
public ActionResult<MyFancyClass> MyFancyAction()
{
return new MyFancyClass {
Property1 = "property 1 content",
Property2 = "property 2 content",
};
}
输出:
{
"Property1": "property 1 content",
"Property2": "property 2 content"
}
问题
.NET Core 3的System.Text.Json内部支持JSON，在上一个示例中使用了它.如果我尝试序列化Manatee.Json.Schema.JsonSchema，它的内部结构将被序列化，而不是json模式本身.
Problem
.NET Core 3 has internal support for JSON with its System.Text.Json which is used in the previous example. If I try to serialize Manatee.Json.Schema.JsonSchema, its internal structure are serialized, not the json schema itself.
示例:
public ActionResult<MyFancyClass2> MyFancyAction2()
{
return new MyFancyClass2 {
Property1 = "property 1 content",
Property1Schema = new JsonSchema()
.Type(JsonSchemaType.String)
};
}
输出:
{
"Property1": "property 1 content",
"Property1Schema": [{
"name":"type",
"supportedVersions":15,
"validationSequence":1,
"vocabulary": {
"id":"https://json-schema.org/draft/2019-09/vocab/validation",
"metaSchemaId":"https://json-schema.org/draft/2019-09/meta/validation"
}
}]
}
我希望这样:
{
"Property1": "property 1 content",
"Property1Schema": {
"type": "string",
}
}
Manatee.Json.JsonValue的内部结构也有冲突，其中System.Text.Json.JsonSerializer无法正确访问内部get方法，例如，我得到以下异常消息:
Manatee.Json.JsonValue also have a conflicting inner structure, where System.Text.Json.JsonSerializer fails to access internal get methods correctly and I get for instance this exception message:
Cannot access value of type Object as type Boolean.
发现
Manatee.Json.Schema.JsonSchema有一个.ToJson()方法，可用于获取作为JsonValue的正确json模式，但随后出现了我刚才提到的序列化Manatee.Json.JsonValue的问题.
Discovery
Manatee.Json.Schema.JsonSchema has a .ToJson() method that can be used to get the correct json schema as a JsonValue, but then I get the problem I just mentioned with serializing Manatee.Json.JsonValue.
问题
有谁知道使System.Text.Json序列化Manatee.Json结构的方法吗?
Question
Does anyone know a way to enable System.Text.Json to serialize Manatee.Json structures?
侧边标记
另一种前进的方式是完全替换System.Text.Json(请查看此问题).
Sidemark
Another way forward is to replace System.Text.Json altogether (take a look at this question).
推荐答案
.NET Core 3 json序列化带有许多配置选项.其中之一是添加指定应如何序列化不同类型的转换器.前进的一种方法是为JsonSchema创建一个JsonConverter，为JsonValue创建另一个.
.NET Core 3 json serialization comes with a lot of configuration options. One of them is to add converters that specify how different types should be serialized. One way forward is to create a JsonConverter for JsonSchema and another for JsonValue.
对于JsonSchema，我们可以实现JsonSchemaConverter，当序列化/写入时，将json模式提取为JsonValue，然后要求序列化程序序列化该JsonValue.像这样:
For JsonSchema we can implement a JsonSchemaConverter that when serializing/writing, extracts the json schema as a JsonValue and ask the serializer to serialize that JsonValue instead. Like this:
public class JsonSchemaConverter : JsonConverter<JsonSchema>
{
public JsonSchemaConverter()
{
_manateeSerializer = new ManateeSerializer();
}
private ManateeSerializer _manateeSerializer { get; set; }
public override JsonSchema Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
{
var jsonText = reader.GetString();
var jsonValue = JsonValue.Parse(jsonText);
return _manateeSerializer.Deserialize<JsonSchema>(jsonValue);
}
public override void Write(Utf8JsonWriter writer, JsonSchema value, JsonSerializerOptions options)
{
var schemaAsJson = value.ToJson(_manateeSerializer);
try
{
System.Text.Json.JsonSerializer.Serialize<JsonValue>(writer, schemaAsJson, options);
}
catch (Exception e)
{
Log.Information($"Failed to serialize JsonSchema ({e.Message});");
writer.WriteNullValue();
}
}
}
对于JsonValue，我们可以将其更改为System.Text.Json可以理解的内容，因为它毕竟是json.一种不幸的方法是将JsonValue序列化为string，并使用例如JsonDocument.Parse(string)对其进行解析并序列化其RootElement属性.感觉没有必要通过JsonDocument，因此，如果有人找到更好的解决方案，那就太好了！
可能的实现如下所示:
For JsonValue we can change it into something System.Text.Json understands, since it is json after all. One unfortunate approach is to serialize the JsonValue to a string, parsing it with for instance JsonDocument.Parse(string) and serialize its RootElement property. It feels so unnecessary to go via JsonDocument, so if anyone finds a better solution that would be great!
A possible implementation can look like this:
public class JsonValueConverter : JsonConverter<JsonValue>
{
public override JsonValue Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
{
var json = reader.GetString();
return JsonValue.Parse(json);
}
public override void Write(Utf8JsonWriter writer, JsonValue value, JsonSerializerOptions options)
{
string content = value.ToString();
try
{
var jsonDocument = JsonDocument.Parse(content);
JsonSerializer.Serialize<JsonElement>(writer, jsonDocument.RootElement, options);
}
catch (Exception e)
{
Log.Warning($"JsonDocument.Parse(JsonValue) failed in JsonValueConverter.Write(,,).\n{e.Message}");
writer.WriteNullValue();
}
}
}
它们必须在Startup.cs处这样注册:
They must be registered at Startup.cs like this:
public void ConfigureServices(IServiceCollection services)
{
services.AddControllers()
.AddJsonOptions(options =>
{
options.JsonSerializerOptions.Converters.Add(new JsonValueConverter());
options.JsonSerializerOptions.Converters.Add(new JsonSchemaConverter());
});
}
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