通过扭曲从 POJO 生成 Json 架构

Question

我有：

我正在从 pojo 生成 JSON 架构。我生成架构的代码如下所示：

ObjectMapper mapper = new ObjectMapper();
TitleSchemaFactoryWrapper visitor = new TitleSchemaFactoryWrapper();
mapper.acceptJsonFormatVisitor(clazz, visitor);
JsonSchema schema = visitor.finalSchema();
schemas.put(clazz, mapper.writerWithDefaultPrettyPrinter().writeValueAsString(schema));

我正在通过上述代码生成多个模式。其中一个 pojo 有一个内部嵌入式枚举来限制可能的值，如下所示：

public class MyClass {

    @JsonProperty("name")
    private String name;
    @JsonProperty("startDayOfWeek")
    private MyClass.StartDayOfWeek startDayOfWeek;
    /**
     * The ID of a timezone returned by the timezones route.
     * 
     */
    @JsonProperty("timezone")
    private String timezone;
    @JsonIgnore
    private Map<String, Object> additionalProperties = new HashMap<String, Object>();

    /**
     * 
     * @return
     *     The startDayOfWeek
     */
    @JsonProperty("startDayOfWeek")
    public MyClass.StartDayOfWeek getStartDayOfWeek() {
        return startDayOfWeek;
    }

    /**
     * 
     * @param startDayOfWeek
     *     The startDayOfWeek
     */
    @JsonProperty("startDayOfWeek")
    public void setStartDayOfWeek(MyClass.StartDayOfWeek startDayOfWeek) {
        this.startDayOfWeek = startDayOfWeek;
    }

    public static enum StartDayOfWeek {

        MONDAY("Monday"),
        TUESDAY("Tuesday"),
        WEDNESDAY("Wednesday"),
        THURSDAY("Thursday"),
        FRIDAY("Friday"),
        SATURDAY("Saturday"),
        SUNDAY("Sunday");
        private final String value;
        private static Map<String, MyClass.StartDayOfWeek> constants = new HashMap<String, MyClass.StartDayOfWeek>();

        static {
            for (MyClass.StartDayOfWeek c: values()) {
                constants.put(c.value, c);
            }
        }

        private StartDayOfWeek(String value) {
            this.value = value;
        }

        @JsonValue
        @Override
        public String toString() {
            return this.value;
        }

        @JsonCreator
        public static MyClass.StartDayOfWeek fromValue(String value) {
            MyClass.StartDayOfWeek constant = constants.get(value);
            if (constant == null) {
                throw new IllegalArgumentException(value);
            } else {
                return constant;
            }
        }

    }

}

以上代码应限制传递给 "Monday"、"Tuesday"、"Wednesday" 等的 JSON 数据中可能的字符串值

当我运行模式生成器处理有问题的代码时，我希望得到类似于以下模式的内容：

{
  "type" : "object",
  "javaType" : "my.package.MyClass",
  "properties": {
    "startDayOfWeek" : {
      "type" : "string",
      "enum" : [ "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday" ]
    }
  }
}

但我得到的是：

{
  "type" : "object",
  "id" : "urn:jsonschema:my:package:MyClass",
  "title" : "Lmy/package/MyClass;",
  "properties" : {
    "startDayOfWeek" : {
      "type" : "string"
    }
  }
}

我在 Jackson 模式模块源代码中做了一些挖掘，发现正在发生的事情是 Jackson 使用“.toString()”作为枚举类型的默认序列化方法，但我需要它来做是基于 StartDayOfWeek.values():

创建看起来像这样的行

"enum" : [ "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday" ]

有人知道怎么做吗？

Answer 1

使用我发现的使用数据绑定的说明似乎是不可能的。但是我发现了另一个 jackson 模块，它似乎可以很好地解决这个问题。奇怪的是，有几个对象的名称相同。

TLDR：使用 org.codehaus.jackson.map 包中的对象而不是 com.fasterxml.jackson.databind 包中的对象。如果您按照 this 页面上的说明进行操作，那么您做错了。只需使用 jackson-mapper 模块即可。

这是供未来 google 员工使用的代码：

private static String getJsonSchema(Class clazz) throws IOException {
    org.codehaus.jackson.map.ObjectMapper mapper = new ObjectMapper();
    //There are other configuration options you can set.  This is the one I needed.
    mapper.configure(SerializationConfig.Feature.WRITE_ENUMS_USING_TO_STRING, true);

    JsonSchema schema = mapper.generateJsonSchema(clazz);

    return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(schema);
}

Answer 2

Storme 的回答引用了 org.codehaus，这是 jackson 的旧版本。以下类似，但使用 fasterxml（较新版本）。

Pom:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.7.1</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.7.1</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-annotations</artifactId>
    <version>2.7.1</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.module</groupId>
    <artifactId>jackson-module-jsonSchema</artifactId>
    <version>2.1.0</version>
</dependency>

代码：

import ...TargetClass;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.jsonschema.JsonSchema;

import java.io.IOException;

public final class JsonSchemaGenerator {

    private JsonSchemaGenerator() { };

    public static void main(String[] args) throws IOException {
        System.out.println(JsonSchemaGenerator.getJsonSchema(TargetClass.class));
    }

    public static String getJsonSchema(Class clazz) throws IOException {
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(SerializationFeature.WRITE_ENUMS_USING_TO_STRING, true);
        JsonSchema schema = mapper.generateJsonSchema(clazz);
        return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(schema);
    }

}

Answer 3

如果有人来到这里并希望在他的代码中支持最新的草稿版本。

在此处查找您的首选语言： https://json-schema.org/implementations.html

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