LazyInitializationException on an entity with ManyToMany, pagination and mapstruct

Overview of the issue

Hibernate throws an exception when trying to get all Job entities after creating a Job entity.

Exception in com.jhipster.web.rest.JobResource.getAllJobs() with cause = 'NULL' and exception = 'failed to lazily initialize a collection of role: com.jhipster.domain.Job.tasks, could not initialize proxy - no Session'

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.jhipster.domain.Job.tasks, could not initialize proxy - no Session
	at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:582)
	at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:201)
	at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:561)
	at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:132)
	at org.hibernate.collection.internal.PersistentSet.iterator(PersistentSet.java:163)
	at com.jhipster.service.mapper.JobMapperImpl.taskSetToTaskDTOSet(JobMapperImpl.java:140)
	at com.jhipster.service.mapper.JobMapperImpl.jobToJobDTO(JobMapperImpl.java:58)
	at com.jhipster.service.mapper.JobMapperImpl.jobsToJobDTOs(JobMapperImpl.java:81)

Motivation for or Use Case

This issue only appears when having an entity with a ManyToMany relationship, being paginated (pager, pagination or infinite-scroll) and dto generated with mapstruct. It’s a little specific but if you use the default JDL from JDL Studio you will have the issue.

Reproduce the error

Use the JDL below to generate entities. Create a Job entity with no Task. An exception will be thrown when displaying all Job.

Related issues

Found nothing related.

Suggest a Fix

Maybe by doing an eager load on the ManyToMany relationship like it’s done when Job is not paginated.

JHipster Version(s)

4.3.0

JHipster configuration

JHipster Version(s)

jhipster@0.0.0 /Users/Theo/Documents/perso/jhipster-issues
└── generator-jhipster@4.3.0

JHipster configuration, a .yo-rc.json file generated in the root folder

{
  "generator-jhipster": {
    "promptValues": {
      "packageName": "com.jhipster"
    },
    "jhipsterVersion": "4.3.0",
    "baseName": "jhipster",
    "packageName": "com.jhipster",
    "packageFolder": "com/jhipster",
    "serverPort": "8080",
    "authenticationType": "session",
    "hibernateCache": "ehcache",
    "clusteredHttpSession": false,
    "websocket": false,
    "databaseType": "sql",
    "devDatabaseType": "h2Disk",
    "prodDatabaseType": "mysql",
    "searchEngine": false,
    "messageBroker": false,
    "serviceDiscoveryType": false,
    "buildTool": "maven",
    "enableSocialSignIn": false,
    "rememberMeKey": "2b4523900caffa3f139b0240dc516cfd9735ba18",
    "clientFramework": "angular1",
    "useSass": false,
    "clientPackageManager": "yarn",
    "applicationType": "monolith",
    "testFrameworks": [],
    "jhiPrefix": "jhi",
    "enableTranslation": false
  }
}

Entity configuration(s) entityName.json files generated in the .jhipster directory

Job.json

{
    "fluentMethods": true,
    "relationships": [
        {
            "relationshipType": "many-to-many",
            "otherEntityRelationshipName": "job",
            "relationshipName": "task",
            "otherEntityName": "task",
            "otherEntityField": "id",
            "ownerSide": true
        }
    ],
    "fields": [
        {
            "fieldName": "jobTitle",
            "fieldType": "String"
        }
    ],
    "changelogDate": "20170420032832",
    "entityTableName": "job",
    "dto": "mapstruct",
    "pagination": "pagination",
    "service": "no"
}

Task.json

{
    "fluentMethods": true,
    "relationships": [
        {
            "relationshipType": "many-to-many",
            "relationshipName": "job",
            "otherEntityName": "job",
            "ownerSide": false,
            "otherEntityRelationshipName": "task"
        }
    ],
    "fields": [
        {
            "fieldName": "title",
            "fieldType": "String"
        }
    ],
    "changelogDate": "20170420032831",
    "entityTableName": "task",
    "dto": "mapstruct",
    "pagination": "no",
    "service": "no"
}

Browsers and Operating System

java version “1.8.0_92” Java™ SE Runtime Environment (build 1.8.0_92-b14) Java HotSpot™ 64-Bit Server VM (build 25.92-b14, mixed mode)

git version 2.10.1 (Apple Git-78)

node: v7.8.0

npm: 4.2.0

bower: 1.8.0

gulp: [23:47:04] CLI version 1.2.2 [23:47:04] Local version 3.9.1

yeoman: 1.8.5

yarn: 0.22.0

Docker version 17.03.1-ce, build c6d412e

docker-compose version 1.11.2, build dfed245

Entity configuration(s) entityName.json files generated in the .jhipster directory

JDL

entity Task {
	title String
}

entity Job {
	jobTitle String
}

relationship ManyToMany {
	Job{task} to Task{job}
}

paginate Job with pagination
dto * with mapstruct

Browsers and Operating System

Chrome 57 on OS X El Capitan

• Checking this box is mandatory (this is just to show you read everything)

[deepu105]

@gzsombor @jdubois what you think of showing DTO and Filter option only when Service is selected? it will atleast solve these kind of issues

[gzsombor]

The better solution is to fix the transaction handling :

• either put the mapper code inside the service (which already has @Transactional annotation)
• or if you insist on not using services, put @Transactional annotation on your rest methods.

Basically, you need to access your database from a code block, which is in a ‘JPA/hibernate session’