登录
当前位置： 首页 > 知识库问答 >
问题：

无法编写JSON：未能懒洋洋地初始化role集合：com.managem.model.region.pays，无法初始化代理-没有会话

丌官坚秉
2023-03-14 
WARNING: Resolved [org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: failed to lazily initialize a collection of role: com.managem.model.Region.pays, could not initialize proxy - no Session; nested exception is com.fasterxml.jackson.databind.JsonMappingException: failed to lazily initialize a collection of role: com.managem.model.Region.pays, could not initialize proxy - no Session (through reference chain: java.util.ArrayList[0]->com.managem.model.Region["pays"])]

@Entity
public class Region {

@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id_Region;

private String region;

private String description;

@OneToMany(mappedBy="region", 
        cascade= {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH, CascadeType.DETACH})
private List<Pays> pays;

public List<Pays> getPays() {
    return pays;
}
public void setPays(List<Pays> pays) {
    this.pays = pays;
}
public int getIdRegion() {
    return id_Region;
}
public void setIdRegion(int idRegion) {
    this.id_Region = idRegion;
}
public String getRegion() {
    return region;
}
public void setRegion(String region) {
    this.region = region;
}
public String getDescription() {
    return description;
}
public void setDescription(String description) {
    this.description = description;
}
public void add(Pays tempPays) {
    if (pays==null) {
        pays=new ArrayList<Pays>();
    }
    pays.add(tempPays);
    tempPays.setRegion(this);
}
@Override
public String toString() {
    return "Region [idRegion=" + id_Region + ", region=" + region + ", description=" + description + ", pays=" + pays
            + "]";
}

@Repository
public class RegionDAOImpl implements RegionDAO {

@Autowired
private SessionFactory sessionFactory;

@Override
public List<Region> listRegion() {

    //retrieve the current Session and put it the session created
    Session session = sessionFactory.getCurrentSession();

    //create a query to get all the instances
    Query<Region> query = session.createQuery("from Region", Region.class);

    //return the list of results
    return query.getResultList();

}

@Override
public Region getRegion(long id) {

    //create a horairePostes instance and fill it with the object retrieved from the database
    Region region = sessionFactory.getCurrentSession().get(Region.class, id);

    //return the instance
    return region;

}

@Override
public long save(Region region) {

    //get the current session and save the object passed in the arguments
    sessionFactory.getCurrentSession().save(region);

    //return the object's id
    return region.getIdRegion();

}

@Override
public void deleteRegion(long id) {

    //retrieve the current session
    Session session = sessionFactory.getCurrentSession();

    //create a Region instance 
    //load the object corresponding to the id in the arguments in it
    Region region = session.byId(Region.class).load(id);

    //delete the object
    session.delete(region);

}

@Override
public void updateRegion(long id, Region region) {

    //retrieve the current session
    Session session = sessionFactory.getCurrentSession();

    //create a Region instance 
    //load the object corresponding to the id in the arguments in it
    Region old_region = session.byId(Region.class).load(id);

    //update old_region with the values in the region
    old_region.setRegion(region.getRegion());
    old_region.setDescription(region.getRegion());

    //execute the changes (this changes are not committed yet)
    session.flush();

}

@Service
public class RegionServiceImpl implements RegionService {

@Autowired
private RegionDAO regionDao;

@Override
@Transactional
public List<Region> listRegion() {
    return regionDao.listRegion();
}

@Override
@Transactional
public Region getRegion(long id) {
    return regionDao.getRegion(id);
}

@Override
@Transactional
public long save(Region region) {
    return regionDao.save(region);
}

@Override
@Transactional
public void deleteRegion(long id) {
    regionDao.deleteRegion(id);
}

@Override
@Transactional
public void updateRegion(long id, Region region) {
    regionDao.updateRegion(id, region);
}

@RestController
public class RegionController {

@Autowired
private RegionService regionService;

//Get all the regions
@GetMapping("/api/region")
public ResponseEntity<List<Region>> list(){
    List<Region> list = regionService.listRegion();
    return ResponseEntity.ok().body(list);
}

<project xmlns="http://maven.apache.org/POM/4.0.0" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.managem</groupId>
<artifactId>gestionMines</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>


<dependencies>

<!-- https://mvnrepository.com/artifact/junit/junit -->
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
    <scope>test</scope>
</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-core -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-core</artifactId>
    <version>5.1.3.RELEASE</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>5.1.3.RELEASE</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.1.3.RELEASE</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-orm -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-orm</artifactId>
    <version>5.1.4.RELEASE</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework.security/spring-security-web -->
<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-web</artifactId>
    <version>5.1.2.RELEASE</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework.security/spring-security-config -->
<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-config</artifactId>
    <version>5.1.2.RELEASE</version>
</dependency>

<!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>3.1.0</version>
    <scope>provided</scope>
</dependency>

<!-- https://mvnrepository.com/artifact/javax.servlet.jsp/javax.servlet.jsp-api -->
<dependency>
    <groupId>javax.servlet.jsp</groupId>
    <artifactId>javax.servlet.jsp-api</artifactId>
    <version>2.3.1</version>
    <scope>provided</scope>
</dependency>

<!-- https://mvnrepository.com/artifact/javax.servlet/jstl -->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jstl</artifactId>
    <version>1.2</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-core</artifactId>
    <version>5.2.4.Final</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-validator -->
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-validator</artifactId>
    <version>5.2.4.Final</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-validator-cdi -->
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-validator-cdi</artifactId>
    <version>5.4.2.Final</version>
</dependency>


<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-c3p0 -->
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-c3p0</artifactId>
    <version>5.2.4.Final</version>
</dependency>   

<!-- https://mvnrepository.com/artifact/com.mchange/c3p0 -->
<dependency>
    <groupId>com.mchange</groupId>
    <artifactId>c3p0</artifactId>
    <version>0.9.5.3</version>
</dependency>

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.38</version>
</dependency>

<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.8</version>
</dependency>


</dependencies>


<build>
    <sourceDirectory>src</sourceDirectory>
    <plugins>
        <plugin> 
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.1</version>
            <configuration> 
                <source>1.8</source> 
                <target>1.8</target> 
            </configuration> 
        </plugin>

        <!-- <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-surefire-plugin</artifactId>
            <version>3.0.0-M3</version>
        </plugin> -->

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-war-plugin</artifactId>
            <version>3.2.0</version>
        </plugin>
    </plugins> 
 </build>
 </project>

我得到的错误是：

键入Rapport D'异常

Could not write JSON: failed to lazily initialize a collection of role: com.managem.model.Region.pays, could not initialize proxy - no Session; nested exception is com.fasterxml.jackson.databind.JsonMappingException: failed to lazily initialize a collection of role: com.managem.model.Region.pays, could not initialize proxy - no Session (through reference chain: java.util.ArrayList[0]-&gt;com.managem.model.Region[&quot;pays&quot;])

描述Le serveur a rencontréune erreur interne qui léa satisfaire la requute.

org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: failed to lazily initialize a collection of role: com.managem.model.Region.pays, could not initialize proxy - no Session; nested exception is com.fasterxml.jackson.databind.JsonMappingException: failed to lazily initialize a collection of role: com.managem.model.Region.pays, could not initialize proxy - no Session (through reference chain: java.util.ArrayList[0]->com.managem.model.Region["pays"])
    org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:296)
    org.springframework.http.converter.AbstractGenericHttpMessageConverter.write(AbstractGenericHttpMessageConverter.java:103)
    org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:289)
    org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(HttpEntityMethodProcessor.java:223)
    org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:82)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:119)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

com.fasterxml.jackson.databind.JsonMappingException: failed to lazily initialize a collection of role: com.managem.model.Region.pays, could not initialize proxy - no Session (through reference chain: java.util.ArrayList[0]->com.managem.model.Region["pays"])
    com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:394)
    com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:353)
    com.fasterxml.jackson.databind.ser.std.StdSerializer.wrapAndThrow(StdSerializer.java:316)
    com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:727)
    com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)
    com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:145)
    com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:107)
    com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25)
    com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480)
    com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:400)
    com.fasterxml.jackson.databind.ObjectWriter$Prefetch.serialize(ObjectWriter.java:1392)
    com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:913)
    org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:287)
    org.springframework.http.converter.AbstractGenericHttpMessageConverter.write(AbstractGenericHttpMessageConverter.java:103)
    org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:289)
    org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(HttpEntityMethodProcessor.java:223)
    org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:82)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:119)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

原因mère

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.managem.model.Region.pays, could not initialize proxy - no Session
    org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:582)
    org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:201)
    org.hibernate.collection.internal.AbstractPersistentCollection.readSize(AbstractPersistentCollection.java:145)
    org.hibernate.collection.internal.PersistentBag.size(PersistentBag.java:261)
    com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:97)
    com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25)
    com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727)
    com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719)
    com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)
    com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:145)
    com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:107)
    com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25)
    com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480)
    com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:400)
    com.fasterxml.jackson.databind.ObjectWriter$Prefetch.serialize(ObjectWriter.java:1392)
    com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:913)
    org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:287)
    org.springframework.http.converter.AbstractGenericHttpMessageConverter.write(AbstractGenericHttpMessageConverter.java:103)
    org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:289)
    org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(HttpEntityMethodProcessor.java:223)
    org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:82)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:119)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

注意La trace complète de La case mère de cette erreur est disponible dans les fichiers journaux de ce serveur。

共有1个答案

荆城
2023-03-14

错误是因为控制器的responseentity.ok().body(list)调用方法region.getpays()来获取列表中每个区域的支付，同时尝试构造JSON来填充响应。问题是，由于pays集合是惰性的（默认情况下），Hibernate试图从数据库中获取该集合。但是您的实体是分离的（您在事务的范围之外），因此出现了错误。

解决方案

您需要急切地获取pays，方法包括：

@OneToMany(mappedBy="region", 
        cascade= {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH, CascadeType.DETACH}, fetch = FetchType.EAGER)
private List<Pays> pays;

 Query<Region> query = session.createQuery("from Region r JOIN FETCH r.pays", Region.class);
 类似资料：

相关问答

Facting未能懒惰地初始化集合，无法初始化代理-没有会话未能懒惰地初始化角色集合 []，无法初始化代理 - 无会话Hibernate：LazyInitializationException：未能懒惰地初始化角色集合。无法初始化代理-没有会话无法懒惰地初始化角色集合：Usuario.autorizacoes，无法初始化代理-无会话未能延迟初始化集合…，无法初始化代理-无会话

相关文章

Hibernate无法初始化代理-没有会话Hibernate：org.hibernate.LazyInitializationException：无法初始化代理-没有会话org.hibernate.LazyInitializationException：无法初始化代理-没有会话？如何修复Hibernate LazyInitializationException：无法延迟初始化角色集合，无法初始化代理-没有会话Grails GORM：无法初始化代理-没有会话

相关阅读

九大组件利用Spring事件机制初始化初中毕业能学会编程吗？Linux初始组和附加组太初 算法工程化工程师一面洋葱学园一面凉经

相关工具

Vue-roleassume-roleansible-role-mysqlRole Playing ToolsNCMusicEngine 优化

相关文档

产品经理进化论：AI+时代产品经理的思维方法从零开始的 JSON 库教程初识 Spring Security怎样优化 Pentium 系列处理器的代码Scala 初学指南
快捷导航： 新手教程 算法原理 架构设计 Java进阶 数据库进阶 大厂专栏 面试经验 编程笔记 编程问答 所有专题 文档资料 工具软件 电子书籍 小牛导航
在线工具： 房贷计算器 个税计算器 Linux命令查询 Json格式化 正则表达式 颜色转换 AES加解密 SHA1加密 MD5加密 毒鸡汤 字数统计 随机密码生成 进制转换 Base64编解码 励志句子
Copyright © 2019-2024 小牛知识库@xnip.cn. All Rights Reserved.