openapi springboot 生成器 jackson no String-argument constructor/factory 方法，用于从 String 值反序列化

java nullable jackson spring-boot openapi-generator

2022-09-03 12:39:39

我正在使用生成器来生成控制器接口和模型。这将创建具有可为空字段的模型类。但是，在发送请求时，我收到类型定义错误，其值存在于可为空的字段中。OpenApiSpringBootJsonNullable<String>JacksonPOST

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.openapitools.jackson.nullable.JsonNullable` (no Creators, like default construct, exist): no String-argument constructor/factory method to deserialize from String value ('TG')
 at [Source: (PushbackInputStream); line: 3, column: 19] (through reference chain: com.example.rest.CreateRequest["displayName"])
    at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1452) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1028) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.deser.ValueInstantiator._createFromStringFallbacks(ValueInstantiator.java:371) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator.createFromString(StdValueInstantiator.java:323) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromString(BeanDeserializerBase.java:1373) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:171) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:161) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:127) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:369) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:159) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4013) ~[jackson-databind-2.9.7.jar:2.9.7]
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3084) ~[jackson-databind-2.9.7.jar:2.9.7]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:239) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:227) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:204) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:157) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:130) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:126) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]

同样的事情发生在或任何其他类型。如果请求仅包含字段，则此方法有效。Integernon-nullable

任何想法这里出了什么问题？

答案 1

OpenAPI生成器团队实现了jackson-databind-nullable模块，您应该将其包含在项目中。最新版本为 0.2.3。

<dependency>
    <groupId>org.openapitools</groupId>
    <artifactId>jackson-databind-nullable</artifactId>
    <version>0.2.3</version>
</dependency>

如果无法自动检测到模块，则需要通过以下方式手动执行此操作：

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JsonNullableModule());

或者，如果您在项目中使用Jackson，则可以通过以下方式注册它：Spring

@Bean
@Primary
public Jackson2ObjectMapperBuilder customObjectMapper() {
    return new Jackson2ObjectMapperBuilder()
            // other configs are possible
            .modules(new JsonNullableModule());
}

答案 2

正如@Micha ł Ziober所说，你必须将 jackson-databind-nullable 添加到你的 maven 依赖项中，并且需要注册 jackson 模块。不过，最简单的方法是将以下内容添加到应用程序中：

@Configuration
public class JacksonConfig {
  @Bean
  public Module jsonNullableModule() {
    return new JsonNullableModule();
  }
}

Spring会自动将Jackson Modules添加到ObjectMapper中，正如文档所说：

任何 com.fasterxml.jackson.databind.Module 类型的 bean 都会自动注册到自动配置的 Jackson2ObjectMapperBuilder 中，并应用于它创建的任何 ObjectMapper 实例。这提供了一种全局机制，用于在向应用程序添加新功能时提供自定义模块。