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spring -boot-start -data-rest OneToMany和ManyToOne和收集空指针异常POS



我有这个有趣的问题，试图POST一个JSON字符串到一个我正在工作的HATEOAS REST服务。

当我发布这个

{
    "type" : "Ladies",
    "name" : "Pants",
    "description" : "This is a test category
}

没有Product Collection，我得到所需的响应201,Created.

但是当我试图发布这个

{
    "type" : "Ladies",
    "name" : "Pants",
    "description" : "This is a test category",
    "products" : [
        {
            "type" : "some type",
            "name" : "Super shoes"
        },
        {
            "type" : "some type 2",
            "name" : "Super shoes 2"
        }
    ]
}

我得到以下错误:

[qtp655641627-165] ERROR org.springframework.data.rest.webmvc.AbstractRepositoryRestController - Could not read JSON: (was java.lang.NullPointerException) (through reference chain: test.Category["products"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: test.Category["products"])
org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: (was java.lang.NullPointerException) (through reference chain: test.Category["products"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: test.Category["products"])
    at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readJavaType(MappingJackson2HttpMessageConverter.java:228)
    at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readInternal(MappingJackson2HttpMessageConverter.java:212)
    at org.springframework.http.converter.AbstractHttpMessageConverter.read(AbstractHttpMessageConverter.java:159)
    at org.springframework.data.rest.webmvc.config.PersistentEntityResourceHandlerMethodArgumentResolver.resolveArgument(PersistentEntityResourceHandlerMethodArgumentResolver.java:100)
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:79)
    at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:157)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:124)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:751)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1666)
    at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:110)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1636)
    at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextFilterConfiguration$1.doFilterInternal(EndpointWebMvcAutoConfiguration.java:257)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1636)
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1636)
    at org.springframework.boot.actuate.autoconfigure.MetricFilterAutoConfiguration$MetricsFilter.doFilterInternal(MetricFilterAutoConfiguration.java:85)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1636)
    at org.springframework.boot.context.web.ErrorPageFilter.doFilter(ErrorPageFilter.java:101)
    at org.springframework.boot.context.web.ErrorPageFilter.doFilter(ErrorPageFilter.java:89)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1636)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:564)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
    at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:578)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:221)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1111)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:498)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:183)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1045)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
    at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:199)
    at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:109)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:98)
    at org.eclipse.jetty.server.Server.handle(Server.java:461)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:284)
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:244)
    at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:534)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:607)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:536)
    at java.lang.Thread.run(Thread.java:744)
Caused by: com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: test.Category["products"])
    at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:232)
    at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:197)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.wrapAndThrow(BeanDeserializerBase.java:1420)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:244)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:118)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2993)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2158)
    at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readJavaType(MappingJackson2HttpMessageConverter.java:225)
    ... 53 more
Caused by: java.lang.NullPointerException
    at java.net.URI$Parser.parse(URI.java:3023)
    at java.net.URI.<init>(URI.java:595)
    at java.net.URI.create(URI.java:857)
    at org.springframework.data.rest.webmvc.json.PersistentEntityJackson2Module$UriStringDeserializer.deserialize(PersistentEntityJackson2Module.java:359)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:227)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:204)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:23)
    at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:525)
    at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:99)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:242)
    ... 57 more
[qtp655641627-165] ERROR org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver - Failed to invoke @ExceptionHandler method: public org.springframework.http.ResponseEntity<org.springframework.data.rest.webmvc.support.ExceptionMessage> org.springframework.data.rest.webmvc.AbstractRepositoryRestController.handleNotReadable(org.springframework.http.converter.HttpMessageNotReadableException)
org.springframework.web.HttpMediaTypeNotAcceptableException: Could not find acceptable representation
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:121)
    at org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(HttpEntityMethodProcessor.java:125)
    at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:71)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:122)
    at org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver.doResolveHandlerMethodException(ExceptionHandlerExceptionResolver.java:340)
    at org.springframework.web.servlet.handler.AbstractHandlerMethodExceptionResolver.doResolveException(AbstractHandlerMethodExceptionResolver.java:60)
    at org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver.resolveException(AbstractHandlerExceptionResolver.java:138)
    at org.springframework.web.servlet.handler.HandlerExceptionResolverComposite.resolveException(HandlerExceptionResolverComposite.java:75)
    at org.springframework.web.servlet.DispatcherServlet.processHandlerException(DispatcherServlet.java:1161)
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:998)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:952)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:751)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1666)
    at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:110)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1636)
    at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextFilterConfiguration$1.doFilterInternal(EndpointWebMvcAutoConfiguration.java:257)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1636)
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1636)
    at org.springframework.boot.actuate.autoconfigure.MetricFilterAutoConfiguration$MetricsFilter.doFilterInternal(MetricFilterAutoConfiguration.java:85)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1636)
    at org.springframework.boot.context.web.ErrorPageFilter.doFilter(ErrorPageFilter.java:101)
    at org.springframework.boot.context.web.ErrorPageFilter.doFilter(ErrorPageFilter.java:89)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1636)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:564)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
    at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:578)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:221)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1111)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:498)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:183)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1045)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
    at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:199)
    at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:109)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:98)
    at org.eclipse.jetty.server.Server.handle(Server.java:461)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:284)
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:244)
    at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:534)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:607)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:536)
    at java.lang.Thread.run(Thread.java:744)
以下是我的ORM模型: 
package test;
import java.io.Serializable;
import java.math.BigInteger;
import javax.persistence.Cacheable;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import lombok.Data;
import lombok.EqualsAndHashCode;
import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;
@Data
@Entity
@Cacheable
@Table(name = "PRODUCT")
@EqualsAndHashCode(of = {"id"})
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE, region = "sorElements")
public class Product implements Serializable {
    private static final long serialVersionUID = 8969734693918596364L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private BigInteger id;
    private String name;
    private String type;
    @ManyToOne(optional = false)
    @JoinColumn(name = "parent_id", referencedColumnName = "id")
    private Category category;
}

package test;
import java.io.Serializable;
import java.math.BigInteger;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.Cacheable;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import lombok.Data;
import lombok.EqualsAndHashCode;
import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;
@Data
@Entity
@Cacheable
@Table(name = "CATEGORY")
@EqualsAndHashCode(of = {"id"})
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE, region = "sorElements")
public class Category implements Serializable {
    private static final long serialVersionUID = 1131387462609255626L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private BigInteger id;
    private String name;
    private String description;
    @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, mappedBy = "category", fetch = FetchType.EAGER)
    private Set<Product> products = new HashSet<Product>();
}

package test;
import java.math.BigInteger;
import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.data.rest.core.annotation.RepositoryRestResource;
@RepositoryRestResource(collectionResourceRel = "cats", path = "cats")
public interface CategoryRepository extends PagingAndSortingRepository<Category, BigInteger>{
}

我很确定我在这里错过了一些东西，提前感谢

如果您查看堆栈跟踪，您会得到一个提示，Spring正在等待一个URI，而不是一个产品集合。这意味着您应该首先发布产品，然后包含这些产品的uri列表，而不是它们的实际内容。

它曾经可以选择是否发布嵌套/嵌入实体表示或发布链接到已经存在的资源，但沿着这条路的某个地方(我希望是无意的)停止工作。

你可以尝试覆盖spring-data-rest-webmvc版本并降级到2.1.0。RELEASE，以便验证。我还认为这与Spring Data REST中的一个(尚未解决的)bug密切相关:https://jira.spring.io/browse/DATAREST-377.

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