Does JPA/Hibernate save even when not calling persist
em.getTransaction().begin();
StringData sd = em.find(StringData.class, key);
System.out.println("Old value: " + sd.getData());
sd.setData(newValue);
// em.persist(sd);
em.getTransaction().commit();
As you can see, I'm not calling persist, it's commented out, because I'm dry running this code first. However, as it turns out it's not so very dry. Upon inspecting the database, I see the data is changed (fortunately it's a test database).
Apparently my understanding of Hibernate/JPA is flawed. Isn't calling persist always required to change data? And if not, what are the rules on when something is saved?
java hibernate jpa
asked Feb 8 '12 at 16:15
Bart van HeukelomBart van Heukelom
20.8k47154270
add a comment |
em.getTransaction().begin();
StringData sd = em.find(StringData.class, key);
System.out.println("Old value: " + sd.getData());
sd.setData(newValue);
// em.persist(sd);
em.getTransaction().commit();
As you can see, I'm not calling persist, it's commented out, because I'm dry running this code first. However, as it turns out it's not so very dry. Upon inspecting the database, I see the data is changed (fortunately it's a test database).
Apparently my understanding of Hibernate/JPA is flawed. Isn't calling persist always required to change data? And if not, what are the rules on when something is saved?
java hibernate jpa
asked Feb 8 '12 at 16:15
Bart van HeukelomBart van Heukelom
20.8k47154270
but you are calling commit?
– Sergey Benner
Feb 8 '12 at 16:20
add a comment |
em.getTransaction().begin();
StringData sd = em.find(StringData.class, key);
System.out.println("Old value: " + sd.getData());
sd.setData(newValue);
// em.persist(sd);
em.getTransaction().commit();
As you can see, I'm not calling persist, it's commented out, because I'm dry running this code first. However, as it turns out it's not so very dry. Upon inspecting the database, I see the data is changed (fortunately it's a test database).
Apparently my understanding of Hibernate/JPA is flawed. Isn't calling persist always required to change data? And if not, what are the rules on when something is saved?
java hibernate jpa
asked Feb 8 '12 at 16:15
Bart van HeukelomBart van Heukelom
20.8k47154270
em.getTransaction().begin();
StringData sd = em.find(StringData.class, key);
System.out.println("Old value: " + sd.getData());
sd.setData(newValue);
// em.persist(sd);
em.getTransaction().commit();
As you can see, I'm not calling persist, it's commented out, because I'm dry running this code first. However, as it turns out it's not so very dry. Upon inspecting the database, I see the data is changed (fortunately it's a test database).
Apparently my understanding of Hibernate/JPA is flawed. Isn't calling persist always required to change data? And if not, what are the rules on when something is saved?
java hibernate jpa
java hibernate jpa
asked Feb 8 '12 at 16:15
Bart van HeukelomBart van Heukelom
20.8k47154270
asked Feb 8 '12 at 16:15
Bart van HeukelomBart van Heukelom
20.8k47154270
asked Feb 8 '12 at 16:15
Bart van HeukelomBart van Heukelom
20.8k47154270
asked Feb 8 '12 at 16:15
Bart van HeukelomBart van Heukelom
20.8k47154270
asked Feb 8 '12 at 16:15
Bart van HeukelomBart van Heukelom
20.8k47154270
20.8k47154270
but you are calling commit?
– Sergey Benner
Feb 8 '12 at 16:20
add a comment |
but you are calling commit?
– Sergey Benner
Feb 8 '12 at 16:20
but you are calling commit?
– Sergey Benner
Feb 8 '12 at 16:20
but you are calling commit?
– Sergey Benner
Feb 8 '12 at 16:20
add a comment |
2 Answers
2
active
oldest
votes
Yes, managed entities are saved when a flush (flush are also done with a commit) is done if any change is detected, it's called dirty checking.
answered Feb 8 '12 at 16:19
PabloPablo
3,39622443
Good to know. Can that be relied upon, or is apersistcall still wise?
– Bart van Heukelom
Feb 8 '12 at 16:25
@Bart Only managed entities are saved this way, managed means that the entity manager used to load those entities is not closed yet, so be careful. And persist works to create a new entity. If you use it in an already existing entity (like here) it will throw an exception. Take a look at the API: link
– Pablo
Feb 8 '12 at 16:32
But I usepersiston loaded entities all the time, without exceptions.
– Bart van Heukelom
Feb 8 '12 at 16:43
@Bart Strange, in the API for persist: "EntityExistsException - if the entity already exists. (If the entity already exists, the EntityExistsException may be thrown when the persist operation is invoked, or the EntityExistsException or another PersistenceException may be thrown at flush or commit time.) "
– Pablo
Feb 8 '12 at 16:47
1
@Bart OK, it seems that the API is not very accurate, look at the accepted answer: link
– Pablo
Feb 8 '12 at 16:53
add a comment |
StringData sd = em.find(StringData.class, key);
That line of code retrieves the StringData instance sd from the em session, any changes you make will be saved on flush (when transactions ends) because the object instance is associated with the em session (ie managed).
You could detach it, or return it from the method. Outside of the transaction it is not associated with em session and changes will not be persisted until it is re-attached via merge.
answered Feb 8 '12 at 16:26
NimChimpskyNimChimpsky
33.2k46168276
The important part is not that the transaction is commited, the important part is that the entity manager is closed. If the transaction is commited but the entity manager is not closed, the entity is still associated with the entity manager.
– Pablo
Feb 8 '12 at 16:38
@Pablo So what happens if the entity is changed outside the transaction, but within the entity manager?
– Bart van Heukelom
Feb 8 '12 at 17:28
@Bart The entity manager will try to save it the next time that a flush() or commit() is called.
– Pablo
Feb 8 '12 at 17:50
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f9197160%2fdoes-jpa-hibernate-save-even-when-not-calling-persist%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Yes, managed entities are saved when a flush (flush are also done with a commit) is done if any change is detected, it's called dirty checking.
answered Feb 8 '12 at 16:19
PabloPablo
3,39622443
Good to know. Can that be relied upon, or is apersistcall still wise?
– Bart van Heukelom
Feb 8 '12 at 16:25
@Bart Only managed entities are saved this way, managed means that the entity manager used to load those entities is not closed yet, so be careful. And persist works to create a new entity. If you use it in an already existing entity (like here) it will throw an exception. Take a look at the API: link
– Pablo
Feb 8 '12 at 16:32
But I usepersiston loaded entities all the time, without exceptions.
– Bart van Heukelom
Feb 8 '12 at 16:43
@Bart Strange, in the API for persist: "EntityExistsException - if the entity already exists. (If the entity already exists, the EntityExistsException may be thrown when the persist operation is invoked, or the EntityExistsException or another PersistenceException may be thrown at flush or commit time.) "
– Pablo
Feb 8 '12 at 16:47
1
@Bart OK, it seems that the API is not very accurate, look at the accepted answer: link
– Pablo
Feb 8 '12 at 16:53
add a comment |
Yes, managed entities are saved when a flush (flush are also done with a commit) is done if any change is detected, it's called dirty checking.
answered Feb 8 '12 at 16:19
PabloPablo
3,39622443
Good to know. Can that be relied upon, or is apersistcall still wise?
– Bart van Heukelom
Feb 8 '12 at 16:25
@Bart Only managed entities are saved this way, managed means that the entity manager used to load those entities is not closed yet, so be careful. And persist works to create a new entity. If you use it in an already existing entity (like here) it will throw an exception. Take a look at the API: link
– Pablo
Feb 8 '12 at 16:32
But I usepersiston loaded entities all the time, without exceptions.
– Bart van Heukelom
Feb 8 '12 at 16:43
@Bart Strange, in the API for persist: "EntityExistsException - if the entity already exists. (If the entity already exists, the EntityExistsException may be thrown when the persist operation is invoked, or the EntityExistsException or another PersistenceException may be thrown at flush or commit time.) "
– Pablo
Feb 8 '12 at 16:47
1
@Bart OK, it seems that the API is not very accurate, look at the accepted answer: link
– Pablo
Feb 8 '12 at 16:53
add a comment |
Yes, managed entities are saved when a flush (flush are also done with a commit) is done if any change is detected, it's called dirty checking.
answered Feb 8 '12 at 16:19
PabloPablo
3,39622443
Yes, managed entities are saved when a flush (flush are also done with a commit) is done if any change is detected, it's called dirty checking.
answered Feb 8 '12 at 16:19
PabloPablo
3,39622443
answered Feb 8 '12 at 16:19
PabloPablo
3,39622443
answered Feb 8 '12 at 16:19
PabloPablo
3,39622443
answered Feb 8 '12 at 16:19
PabloPablo
3,39622443
3,39622443
Good to know. Can that be relied upon, or is apersistcall still wise?
– Bart van Heukelom
Feb 8 '12 at 16:25
@Bart Only managed entities are saved this way, managed means that the entity manager used to load those entities is not closed yet, so be careful. And persist works to create a new entity. If you use it in an already existing entity (like here) it will throw an exception. Take a look at the API: link
– Pablo
Feb 8 '12 at 16:32
But I usepersiston loaded entities all the time, without exceptions.
– Bart van Heukelom
Feb 8 '12 at 16:43
@Bart Strange, in the API for persist: "EntityExistsException - if the entity already exists. (If the entity already exists, the EntityExistsException may be thrown when the persist operation is invoked, or the EntityExistsException or another PersistenceException may be thrown at flush or commit time.) "
– Pablo
Feb 8 '12 at 16:47
1
@Bart OK, it seems that the API is not very accurate, look at the accepted answer: link
– Pablo
Feb 8 '12 at 16:53
add a comment |
Good to know. Can that be relied upon, or is apersistcall still wise?
– Bart van Heukelom
Feb 8 '12 at 16:25
@Bart Only managed entities are saved this way, managed means that the entity manager used to load those entities is not closed yet, so be careful. And persist works to create a new entity. If you use it in an already existing entity (like here) it will throw an exception. Take a look at the API: link
– Pablo
Feb 8 '12 at 16:32
But I usepersiston loaded entities all the time, without exceptions.
– Bart van Heukelom
Feb 8 '12 at 16:43
@Bart Strange, in the API for persist: "EntityExistsException - if the entity already exists. (If the entity already exists, the EntityExistsException may be thrown when the persist operation is invoked, or the EntityExistsException or another PersistenceException may be thrown at flush or commit time.) "
– Pablo
Feb 8 '12 at 16:47
1
@Bart OK, it seems that the API is not very accurate, look at the accepted answer: link
– Pablo
Feb 8 '12 at 16:53
Good to know. Can that be relied upon, or is a
persist call still wise?– Bart van Heukelom
Feb 8 '12 at 16:25
Good to know. Can that be relied upon, or is a
persist call still wise?– Bart van Heukelom
Feb 8 '12 at 16:25
@Bart Only managed entities are saved this way, managed means that the entity manager used to load those entities is not closed yet, so be careful. And persist works to create a new entity. If you use it in an already existing entity (like here) it will throw an exception. Take a look at the API: link
– Pablo
Feb 8 '12 at 16:32
@Bart Only managed entities are saved this way, managed means that the entity manager used to load those entities is not closed yet, so be careful. And persist works to create a new entity. If you use it in an already existing entity (like here) it will throw an exception. Take a look at the API: link
– Pablo
Feb 8 '12 at 16:32
But I use
persist on loaded entities all the time, without exceptions.– Bart van Heukelom
Feb 8 '12 at 16:43
But I use
persist on loaded entities all the time, without exceptions.– Bart van Heukelom
Feb 8 '12 at 16:43
@Bart Strange, in the API for persist: "EntityExistsException - if the entity already exists. (If the entity already exists, the EntityExistsException may be thrown when the persist operation is invoked, or the EntityExistsException or another PersistenceException may be thrown at flush or commit time.) "
– Pablo
Feb 8 '12 at 16:47
@Bart Strange, in the API for persist: "EntityExistsException - if the entity already exists. (If the entity already exists, the EntityExistsException may be thrown when the persist operation is invoked, or the EntityExistsException or another PersistenceException may be thrown at flush or commit time.) "
– Pablo
Feb 8 '12 at 16:47
1
1
@Bart OK, it seems that the API is not very accurate, look at the accepted answer: link
– Pablo
Feb 8 '12 at 16:53
@Bart OK, it seems that the API is not very accurate, look at the accepted answer: link
– Pablo
Feb 8 '12 at 16:53
add a comment |
StringData sd = em.find(StringData.class, key);
That line of code retrieves the StringData instance sd from the em session, any changes you make will be saved on flush (when transactions ends) because the object instance is associated with the em session (ie managed).
You could detach it, or return it from the method. Outside of the transaction it is not associated with em session and changes will not be persisted until it is re-attached via merge.
answered Feb 8 '12 at 16:26
NimChimpskyNimChimpsky
33.2k46168276
The important part is not that the transaction is commited, the important part is that the entity manager is closed. If the transaction is commited but the entity manager is not closed, the entity is still associated with the entity manager.
– Pablo
Feb 8 '12 at 16:38
@Pablo So what happens if the entity is changed outside the transaction, but within the entity manager?
– Bart van Heukelom
Feb 8 '12 at 17:28
@Bart The entity manager will try to save it the next time that a flush() or commit() is called.
– Pablo
Feb 8 '12 at 17:50
add a comment |
StringData sd = em.find(StringData.class, key);
That line of code retrieves the StringData instance sd from the em session, any changes you make will be saved on flush (when transactions ends) because the object instance is associated with the em session (ie managed).
You could detach it, or return it from the method. Outside of the transaction it is not associated with em session and changes will not be persisted until it is re-attached via merge.
answered Feb 8 '12 at 16:26
NimChimpskyNimChimpsky
33.2k46168276
The important part is not that the transaction is commited, the important part is that the entity manager is closed. If the transaction is commited but the entity manager is not closed, the entity is still associated with the entity manager.
– Pablo
Feb 8 '12 at 16:38
@Pablo So what happens if the entity is changed outside the transaction, but within the entity manager?
– Bart van Heukelom
Feb 8 '12 at 17:28
@Bart The entity manager will try to save it the next time that a flush() or commit() is called.
– Pablo
Feb 8 '12 at 17:50
add a comment |
StringData sd = em.find(StringData.class, key);
That line of code retrieves the StringData instance sd from the em session, any changes you make will be saved on flush (when transactions ends) because the object instance is associated with the em session (ie managed).
You could detach it, or return it from the method. Outside of the transaction it is not associated with em session and changes will not be persisted until it is re-attached via merge.
answered Feb 8 '12 at 16:26
NimChimpskyNimChimpsky
33.2k46168276
StringData sd = em.find(StringData.class, key);
That line of code retrieves the StringData instance sd from the em session, any changes you make will be saved on flush (when transactions ends) because the object instance is associated with the em session (ie managed).
You could detach it, or return it from the method. Outside of the transaction it is not associated with em session and changes will not be persisted until it is re-attached via merge.
answered Feb 8 '12 at 16:26
NimChimpskyNimChimpsky
33.2k46168276
answered Feb 8 '12 at 16:26
NimChimpskyNimChimpsky
33.2k46168276
answered Feb 8 '12 at 16:26
NimChimpskyNimChimpsky
33.2k46168276
answered Feb 8 '12 at 16:26
NimChimpskyNimChimpsky
33.2k46168276
33.2k46168276
The important part is not that the transaction is commited, the important part is that the entity manager is closed. If the transaction is commited but the entity manager is not closed, the entity is still associated with the entity manager.
– Pablo
Feb 8 '12 at 16:38
@Pablo So what happens if the entity is changed outside the transaction, but within the entity manager?
– Bart van Heukelom
Feb 8 '12 at 17:28
@Bart The entity manager will try to save it the next time that a flush() or commit() is called.
– Pablo
Feb 8 '12 at 17:50
add a comment |
The important part is not that the transaction is commited, the important part is that the entity manager is closed. If the transaction is commited but the entity manager is not closed, the entity is still associated with the entity manager.
– Pablo
Feb 8 '12 at 16:38
@Pablo So what happens if the entity is changed outside the transaction, but within the entity manager?
– Bart van Heukelom
Feb 8 '12 at 17:28
@Bart The entity manager will try to save it the next time that a flush() or commit() is called.
– Pablo
Feb 8 '12 at 17:50
The important part is not that the transaction is commited, the important part is that the entity manager is closed. If the transaction is commited but the entity manager is not closed, the entity is still associated with the entity manager.
– Pablo
Feb 8 '12 at 16:38
The important part is not that the transaction is commited, the important part is that the entity manager is closed. If the transaction is commited but the entity manager is not closed, the entity is still associated with the entity manager.
– Pablo
Feb 8 '12 at 16:38
@Pablo So what happens if the entity is changed outside the transaction, but within the entity manager?
– Bart van Heukelom
Feb 8 '12 at 17:28
@Pablo So what happens if the entity is changed outside the transaction, but within the entity manager?
– Bart van Heukelom
Feb 8 '12 at 17:28
@Bart The entity manager will try to save it the next time that a flush() or commit() is called.
– Pablo
Feb 8 '12 at 17:50
@Bart The entity manager will try to save it the next time that a flush() or commit() is called.
– Pablo
Feb 8 '12 at 17:50
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f9197160%2fdoes-jpa-hibernate-save-even-when-not-calling-persist%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
but you are calling commit?
– Sergey Benner
Feb 8 '12 at 16:20