openapi springboot generator jackson 没有 String-argument constructor/factory 方法从 String 值反序列化

Question

我正在使用 OpenApi SpringBoot 生成器来生成控制器接口和模型。这将为可为空的字段创建模型类和 JsonNullable<String>。但是，我收到 Jackson 类型定义错误，而 POST 请求发送时值存在于可空字段中。

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]

Integer 或任何其他类型也会发生同样的事情。如果请求仅包含 non-nullable 个字段，它会起作用。

知道这里出了什么问题吗？

Answer 1

OpenAPI Generator team implemented jackson-databind-nullable module which you should include to your project. The newest version is 0.2.1.

<dependency>
    <groupId>org.openapitools</groupId>
    <artifactId>jackson-databind-nullable</artifactId>
    <version>0.2.1</version>
</dependency>

如果无法自动检测到模块，您需要通过以下方式手动检测：

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

或者如果你在Spring项目中使用Jackson，那么你可以通过以下方式注册：

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

Answer 2

正如@Michał Ziober 所说，您必须将 jackson-databind-nullable 添加到您的 Maven 依赖项中，并且需要注册 jackson 模块。最简单的方法是将以下内容添加到您的应用程序中：

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

Spring 自动将 Jackson 模块添加到 ObjectMapper，如文档所述：

Any beans of type com.fasterxml.jackson.databind.Module are automatically registered with the auto-configured Jackson2ObjectMapperBuilder and are applied to any ObjectMapper instances that it creates. This provides a global mechanism for contributing custom modules when you add new features to your application.

Answer 3

从 openapi-generator v5.1.1 开始，您可以在 config.json:

中使用

{
  "openApiNullable": false
}

删除该依赖项。大多数时候不需要它（如果你检查生成的代码），所以能够不在你的 class 路径中添加不需要的依赖是很酷的。

或者直接在 build.gradle 的 gradle 插件中，您可以：

openApiGenerate {
    generatorName = "spring"
    inputSpec = "$rootDir/specs/petstore-v3.0.yaml"
    outputDir = "$buildDir/generated"
    apiPackage = "org.openapi.example.api"
    modelPackage = "org.openapi.example.model"
    configOptions = [
        openApiNullable: "false"
    ]
}

Answer 4

适用于我的解决方案（除了来自 openapi yaml 的 self-generated 代码）：

<dependency>
    <groupId>org.openapitools</groupId>
    <artifactId>jackson-databind-nullable</artifactId>
    <version>0.2.1</version>
</dependency>

然后在@Configuration中class/es:

@Bean
public JsonNullableModule jsonNullableModule() {
    return new JsonNullableModule();
}

和

@Bean
public RestTemplate restTemplate(ObjectMapper objectMapper) {
    var converter = new MappingJackson2HttpMessageConverter();
    converter.setObjectMapper(objectMapper);
    return new RestTemplateBuilder().additionalMessageConverters(converter).build();
}

Answer 5

这是唯一对我有用的解决方案，它不会破坏在 ObjectMapper

中添加的 post 序列化程序模块

@Configuration
public class WebApplicationConfig implements WebMvcConfigurer {
    
    @Bean
    public MappingJackson2HttpMessageConverter jackson2HttpMessageConverter() {
        return new MappingJackson2HttpMessageConverter(objectMapper());
    }

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.add(new StringHttpMessageConverter());
        converters.add(jackson2HttpMessageConverter());
        converters.add(new ByteArrayHttpMessageConverter());
    }

    public ObjectMapper objectMapper() {
        val mapper = new ObjectMapper();
        mapper.setSerializationInclusion(JsonInclude.Include.ALWAYS);
        mapper.registerModule(new JsonNullableModule());
        mapper.registerModule(new JavaTimeModule());
        mapper.registerModule(new Jdk8Module());
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        return mapper;
    }

}

openapi springboot generator jackson 没有 String-argument constructor/factory 方法从 String 值反序列化

openapi springboot generator jackson no String-argument constructor/factory method to deserialize from String value

java

nullable

jackson

spring-boot

openapi-generator