[appengine-java] Re: JDO Collection of Serializables
@laserjim,
Did you figure this one out? I am running into the same issue.
On Jul 7, 10:46 am, laserjim laser...@gmail.com wrote:
Hey,
I've attached some example code for reference:
public class FooObject implements Serializable
{
private final String name;
public FooObject(String name)
{
this.name = name;
}
public String toString()
{
return name;
}
}
@PersistenceCapable
public class Entity
{
@Element(serialized=true)
ListFooObject foos = new ArrayListFooObject();
public void addFoo(FooObject foo)
{
foos.add(foo);
}
public ListFooObject getFoos()
{
return foos;
}
}
Please let me know if you see the problem.
Thanks!
On Jul 7, 10:30 am, laserjim laser...@gmail.com wrote:
Hey,
I agree that your comments above are true for serialized fields, but I
can't find any documentation indicating such a behavior for
collections (I assume supported collections here, as described in
dataclasses#Collections). My understanding is that a collection
should behave correctly (inserts, deletes, etc) unless the list its
self is serialized. Can you provide a counter-example?
With regards to the article Max Ross wrote (very good article by the
way), the trick he used (where he made a copy in order to change the
reference) was intended to dirty the state when a member is
modified. My FooObjects are immutable, so I don't think this applies
to me. Max Ross' article is completely consistent with my
understanding of the documentation, but it's entirely possible I
missed something, so let me know if this doesn't sound right to you.
I BELIEVE the issue I'm running into is rooted in the exception I get
when trying to persist a populated instance of the list: FooObject is
not a supported property type. I'm just not understanding why it
isn't supported. I would have expected that any serializable object
would be permitted, especially if the @Element(serialized=true)
annotation is specified.
Basically, I'm looking for a code fragment that demonstrates the
persistence of a collection of (more than one) non-standard
serializable objects.
Any ideas?
Thanks!
On Jul 7, 5:05 am, l.denardo lorenzo.dena...@gmail.com wrote:
Hello,
I guess your problem is the behavior of serialized fields (including
collections of them, as far as I know), which is explained in Max
Ross's post.
Or something related to that.
Anyway, some property fields are marked as updated and hence saved
in the datastore only if you update the reference to the field, and
they're not updated if you just use modifiers to operate on them.
In practice, something like
ArrayListFoo list = retrieve from datastore
list.add(Foo foo)
close persistence manager
Does not modify the list in the datastore, so if it's saved as an
empty list at creation it remains empty.
Doing
ArrayListFoo list = retrieve from datastore
ArrayList copy = new ArrayList(list);
copy.add(Foo foo)
list = copy;
close PM
Usually makes everything work, since the original list field is marked
as updated and persisted.
As far as I know this is true both for serialized fields and for many
collections.
Regards
Lorenzo
On Jul 7, 1:28 pm, laserjim laser...@gmail.com wrote:
Hello Lorenzo,
Thanks, but perhaps my question wasn't clear. I'm trying to make a
list of serialized objects, NOT a serialized list of objects.
For instance, assuming FooObject implements Serializable...
@Element(serialized=true)
ListFooObject foos = new ArrayListFooObject();
Unfortunately, the list is always empty. Not quite sure why.
Thanks!
On Jul 7, 2:59 am, l.denardo lorenzo.dena...@gmail.com wrote:
If you are using a serialized field you must add the serialized=true
clause to your annotation
@Persistent(serialized=true)
MySerializableObject serializable;
Also notice that JDO does not automatically detect if you update only
the inner fields of the object you save, so you must substitute it
with a copy to have it persisted.
See this post for a very good overview and an explanation of the fact
above:
http://groups.google.com/group/google-appengine-java/browse_thread/th...
Regards
Lorenzo
On Jul 7, 1:33 am, laserjim laser...@gmail.com wrote:
Hello,
I'm still trying to persist a list of serializable objects. I would
expect this to be a standard collection as described
here:http://code.google.com/appengine/docs/java/datastore/dataclasses.html...
FooObject is serializable, but my attempt gave me an exception:
FooObject is not a supported property type.
Everything works as expected if I replace my serializable class
(FooObject) with String.
How can I persist my list of FooObjects using JDO?
[appengine-java] Re: JDO Collection of Serializables
Are lists @Persistent by default? or is the @Element doing it for you?
On Jul 7, 12:46 pm, laserjim laser...@gmail.com wrote:
Hey,
I've attached some example code for reference:
public class FooObject implements Serializable
{
private final String name;
public FooObject(String name)
{
this.name = name;
}
public String toString()
{
return name;
}
}
@PersistenceCapable
public class Entity
{
@Element(serialized=true)
ListFooObject foos = new ArrayListFooObject();
public void addFoo(FooObject foo)
{
foos.add(foo);
}
public ListFooObject getFoos()
{
return foos;
}
}
Please let me know if you see the problem.
Thanks!
On Jul 7, 10:30 am, laserjim laser...@gmail.com wrote:
Hey,
I agree that your comments above are true for serialized fields, but I
can't find any documentation indicating such a behavior for
collections (I assume supported collections here, as described in
dataclasses#Collections). My understanding is that a collection
should behave correctly (inserts, deletes, etc) unless the list its
self is serialized. Can you provide a counter-example?
With regards to the article Max Ross wrote (very good article by the
way), the trick he used (where he made a copy in order to change the
reference) was intended to dirty the state when a member is
modified. My FooObjects are immutable, so I don't think this applies
to me. Max Ross' article is completely consistent with my
understanding of the documentation, but it's entirely possible I
missed something, so let me know if this doesn't sound right to you.
I BELIEVE the issue I'm running into is rooted in the exception I get
when trying to persist a populated instance of the list: FooObject is
not a supported property type. I'm just not understanding why it
isn't supported. I would have expected that any serializable object
would be permitted, especially if the @Element(serialized=true)
annotation is specified.
Basically, I'm looking for a code fragment that demonstrates the
persistence of a collection of (more than one) non-standard
serializable objects.
Any ideas?
Thanks!
On Jul 7, 5:05 am, l.denardo lorenzo.dena...@gmail.com wrote:
Hello,
I guess your problem is the behavior of serialized fields (including
collections of them, as far as I know), which is explained in Max
Ross's post.
Or something related to that.
Anyway, some property fields are marked as updated and hence saved
in the datastore only if you update the reference to the field, and
they're not updated if you just use modifiers to operate on them.
In practice, something like
ArrayListFoo list = retrieve from datastore
list.add(Foo foo)
close persistence manager
Does not modify the list in the datastore, so if it's saved as an
empty list at creation it remains empty.
Doing
ArrayListFoo list = retrieve from datastore
ArrayList copy = new ArrayList(list);
copy.add(Foo foo)
list = copy;
close PM
Usually makes everything work, since the original list field is marked
as updated and persisted.
As far as I know this is true both for serialized fields and for many
collections.
Regards
Lorenzo
On Jul 7, 1:28 pm, laserjim laser...@gmail.com wrote:
Hello Lorenzo,
Thanks, but perhaps my question wasn't clear. I'm trying to make a
list of serialized objects, NOT a serialized list of objects.
For instance, assuming FooObject implements Serializable...
@Element(serialized=true)
ListFooObject foos = new ArrayListFooObject();
Unfortunately, the list is always empty. Not quite sure why.
Thanks!
On Jul 7, 2:59 am, l.denardo lorenzo.dena...@gmail.com wrote:
If you are using a serialized field you must add the serialized=true
clause to your annotation
@Persistent(serialized=true)
MySerializableObject serializable;
Also notice that JDO does not automatically detect if you update only
the inner fields of the object you save, so you must substitute it
with a copy to have it persisted.
See this post for a very good overview and an explanation of the fact
above:
http://groups.google.com/group/google-appengine-java/browse_thread/th...
Regards
Lorenzo
On Jul 7, 1:33 am, laserjim laser...@gmail.com wrote:
Hello,
I'm still trying to persist a list of serializable objects. I would
expect this to be a standard collection as described
here:http://code.google.com/appengine/docs/java/datastore/dataclasses.html...
FooObject is serializable, but my attempt gave me an exception:
FooObject is not a supported property type.
Everything works as expected if I replace my serializable class
(FooObject) with String.
How can I persist my list of FooObjects using JDO?
Thanks!
[appengine-java] Re: JDO Collection of Serializables
If you are using a serialized field you must add the serialized=true clause to your annotation @Persistent(serialized=true) MySerializableObject serializable; Also notice that JDO does not automatically detect if you update only the inner fields of the object you save, so you must substitute it with a copy to have it persisted. See this post for a very good overview and an explanation of the fact above: http://groups.google.com/group/google-appengine-java/browse_thread/thread/747ceed8396c0ed8/b311227fbe4d9304?lnk=gstq=serialized+fields+snippets+work#b311227fbe4d9304 Regards Lorenzo On Jul 7, 1:33 am, laserjim laser...@gmail.com wrote: Hello, I'm still trying to persist a list of serializable objects. I would expect this to be a standard collection as described here:http://code.google.com/appengine/docs/java/datastore/dataclasses.html... FooObject is serializable, but my attempt gave me an exception: FooObject is not a supported property type. Everything works as expected if I replace my serializable class (FooObject) with String. How can I persist my list of FooObjects using JDO? Thanks! -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: JDO Collection of Serializables
Hello Lorenzo, Thanks, but perhaps my question wasn't clear. I'm trying to make a list of serialized objects, NOT a serialized list of objects. For instance, assuming FooObject implements Serializable... @Element(serialized=true) ListFooObject foos = new ArrayListFooObject(); Unfortunately, the list is always empty. Not quite sure why. Thanks! On Jul 7, 2:59 am, l.denardo lorenzo.dena...@gmail.com wrote: If you are using a serialized field you must add the serialized=true clause to your annotation @Persistent(serialized=true) MySerializableObject serializable; Also notice that JDO does not automatically detect if you update only the inner fields of the object you save, so you must substitute it with a copy to have it persisted. See this post for a very good overview and an explanation of the fact above: http://groups.google.com/group/google-appengine-java/browse_thread/th... Regards Lorenzo On Jul 7, 1:33 am, laserjim laser...@gmail.com wrote: Hello, I'm still trying to persist a list of serializable objects. I would expect this to be a standard collection as described here:http://code.google.com/appengine/docs/java/datastore/dataclasses.html... FooObject is serializable, but my attempt gave me an exception: FooObject is not a supported property type. Everything works as expected if I replace my serializable class (FooObject) with String. How can I persist my list of FooObjects using JDO? Thanks! -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: JDO Collection of Serializables
Hello, I guess your problem is the behavior of serialized fields (including collections of them, as far as I know), which is explained in Max Ross's post. Or something related to that. Anyway, some property fields are marked as updated and hence saved in the datastore only if you update the reference to the field, and they're not updated if you just use modifiers to operate on them. In practice, something like ArrayListFoo list = retrieve from datastore list.add(Foo foo) close persistence manager Does not modify the list in the datastore, so if it's saved as an empty list at creation it remains empty. Doing ArrayListFoo list = retrieve from datastore ArrayList copy = new ArrayList(list); copy.add(Foo foo) list = copy; close PM Usually makes everything work, since the original list field is marked as updated and persisted. As far as I know this is true both for serialized fields and for many collections. Regards Lorenzo On Jul 7, 1:28 pm, laserjim laser...@gmail.com wrote: Hello Lorenzo, Thanks, but perhaps my question wasn't clear. I'm trying to make a list of serialized objects, NOT a serialized list of objects. For instance, assuming FooObject implements Serializable... @Element(serialized=true) ListFooObject foos = new ArrayListFooObject(); Unfortunately, the list is always empty. Not quite sure why. Thanks! On Jul 7, 2:59 am, l.denardo lorenzo.dena...@gmail.com wrote: If you are using a serialized field you must add the serialized=true clause to your annotation @Persistent(serialized=true) MySerializableObject serializable; Also notice that JDO does not automatically detect if you update only the inner fields of the object you save, so you must substitute it with a copy to have it persisted. See this post for a very good overview and an explanation of the fact above: http://groups.google.com/group/google-appengine-java/browse_thread/th... Regards Lorenzo On Jul 7, 1:33 am, laserjim laser...@gmail.com wrote: Hello, I'm still trying to persist a list of serializable objects. I would expect this to be a standard collection as described here:http://code.google.com/appengine/docs/java/datastore/dataclasses.html... FooObject is serializable, but my attempt gave me an exception: FooObject is not a supported property type. Everything works as expected if I replace my serializable class (FooObject) with String. How can I persist my list of FooObjects using JDO? Thanks! -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: JDO Collection of Serializables
Hey, I agree that your comments above are true for serialized fields, but I can't find any documentation indicating such a behavior for collections (I assume supported collections here, as described in dataclasses#Collections). My understanding is that a collection should behave correctly (inserts, deletes, etc) unless the list its self is serialized. Can you provide a counter-example? With regards to the article Max Ross wrote (very good article by the way), the trick he used (where he made a copy in order to change the reference) was intended to dirty the state when a member is modified. My FooObjects are immutable, so I don't think this applies to me. Max Ross' article is completely consistent with my understanding of the documentation, but it's entirely possible I missed something, so let me know if this doesn't sound right to you. I BELIEVE the issue I'm running into is rooted in the exception I get when trying to persist a populated instance of the list: FooObject is not a supported property type. I'm just not understanding why it isn't supported. I would have expected that any serializable object would be permitted, especially if the @Element(serialized=true) annotation is specified. Basically, I'm looking for a code fragment that demonstrates the persistence of a collection of (more than one) non-standard serializable objects. Any ideas? Thanks! On Jul 7, 5:05 am, l.denardo lorenzo.dena...@gmail.com wrote: Hello, I guess your problem is the behavior of serialized fields (including collections of them, as far as I know), which is explained in Max Ross's post. Or something related to that. Anyway, some property fields are marked as updated and hence saved in the datastore only if you update the reference to the field, and they're not updated if you just use modifiers to operate on them. In practice, something like ArrayListFoo list = retrieve from datastore list.add(Foo foo) close persistence manager Does not modify the list in the datastore, so if it's saved as an empty list at creation it remains empty. Doing ArrayListFoo list = retrieve from datastore ArrayList copy = new ArrayList(list); copy.add(Foo foo) list = copy; close PM Usually makes everything work, since the original list field is marked as updated and persisted. As far as I know this is true both for serialized fields and for many collections. Regards Lorenzo On Jul 7, 1:28 pm, laserjim laser...@gmail.com wrote: Hello Lorenzo, Thanks, but perhaps my question wasn't clear. I'm trying to make a list of serialized objects, NOT a serialized list of objects. For instance, assuming FooObject implements Serializable... @Element(serialized=true) ListFooObject foos = new ArrayListFooObject(); Unfortunately, the list is always empty. Not quite sure why. Thanks! On Jul 7, 2:59 am, l.denardo lorenzo.dena...@gmail.com wrote: If you are using a serialized field you must add the serialized=true clause to your annotation @Persistent(serialized=true) MySerializableObject serializable; Also notice that JDO does not automatically detect if you update only the inner fields of the object you save, so you must substitute it with a copy to have it persisted. See this post for a very good overview and an explanation of the fact above: http://groups.google.com/group/google-appengine-java/browse_thread/th... Regards Lorenzo On Jul 7, 1:33 am, laserjim laser...@gmail.com wrote: Hello, I'm still trying to persist a list of serializable objects. I would expect this to be a standard collection as described here:http://code.google.com/appengine/docs/java/datastore/dataclasses.html... FooObject is serializable, but my attempt gave me an exception: FooObject is not a supported property type. Everything works as expected if I replace my serializable class (FooObject) with String. How can I persist my list of FooObjects using JDO? Thanks! -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: JDO Collection of Serializables
Hey,
I've attached some example code for reference:
public class FooObject implements Serializable
{
private final String name;
public FooObject(String name)
{
this.name = name;
}
public String toString()
{
return name;
}
}
@PersistenceCapable
public class Entity
{
@Element(serialized=true)
ListFooObject foos = new ArrayListFooObject();
public void addFoo(FooObject foo)
{
foos.add(foo);
}
public ListFooObject getFoos()
{
return foos;
}
}
Please let me know if you see the problem.
Thanks!
On Jul 7, 10:30 am, laserjim laser...@gmail.com wrote:
Hey,
I agree that your comments above are true for serialized fields, but I
can't find any documentation indicating such a behavior for
collections (I assume supported collections here, as described in
dataclasses#Collections). My understanding is that a collection
should behave correctly (inserts, deletes, etc) unless the list its
self is serialized. Can you provide a counter-example?
With regards to the article Max Ross wrote (very good article by the
way), the trick he used (where he made a copy in order to change the
reference) was intended to dirty the state when a member is
modified. My FooObjects are immutable, so I don't think this applies
to me. Max Ross' article is completely consistent with my
understanding of the documentation, but it's entirely possible I
missed something, so let me know if this doesn't sound right to you.
I BELIEVE the issue I'm running into is rooted in the exception I get
when trying to persist a populated instance of the list: FooObject is
not a supported property type. I'm just not understanding why it
isn't supported. I would have expected that any serializable object
would be permitted, especially if the @Element(serialized=true)
annotation is specified.
Basically, I'm looking for a code fragment that demonstrates the
persistence of a collection of (more than one) non-standard
serializable objects.
Any ideas?
Thanks!
On Jul 7, 5:05 am, l.denardo lorenzo.dena...@gmail.com wrote:
Hello,
I guess your problem is the behavior of serialized fields (including
collections of them, as far as I know), which is explained in Max
Ross's post.
Or something related to that.
Anyway, some property fields are marked as updated and hence saved
in the datastore only if you update the reference to the field, and
they're not updated if you just use modifiers to operate on them.
In practice, something like
ArrayListFoo list = retrieve from datastore
list.add(Foo foo)
close persistence manager
Does not modify the list in the datastore, so if it's saved as an
empty list at creation it remains empty.
Doing
ArrayListFoo list = retrieve from datastore
ArrayList copy = new ArrayList(list);
copy.add(Foo foo)
list = copy;
close PM
Usually makes everything work, since the original list field is marked
as updated and persisted.
As far as I know this is true both for serialized fields and for many
collections.
Regards
Lorenzo
On Jul 7, 1:28 pm, laserjim laser...@gmail.com wrote:
Hello Lorenzo,
Thanks, but perhaps my question wasn't clear. I'm trying to make a
list of serialized objects, NOT a serialized list of objects.
For instance, assuming FooObject implements Serializable...
@Element(serialized=true)
ListFooObject foos = new ArrayListFooObject();
Unfortunately, the list is always empty. Not quite sure why.
Thanks!
On Jul 7, 2:59 am, l.denardo lorenzo.dena...@gmail.com wrote:
If you are using a serialized field you must add the serialized=true
clause to your annotation
@Persistent(serialized=true)
MySerializableObject serializable;
Also notice that JDO does not automatically detect if you update only
the inner fields of the object you save, so you must substitute it
with a copy to have it persisted.
See this post for a very good overview and an explanation of the fact
above:
http://groups.google.com/group/google-appengine-java/browse_thread/th...
Regards
Lorenzo
On Jul 7, 1:33 am, laserjim laser...@gmail.com wrote:
Hello,
I'm still trying to persist a list of serializable objects. I would
expect this to be a standard collection as described
here:http://code.google.com/appengine/docs/java/datastore/dataclasses.html...
FooObject is serializable, but my attempt gave me an exception:
FooObject is not a supported property type.
Everything works as expected if I replace my serializable class
(FooObject) with String.
How can I persist my list of FooObjects using JDO?
Thanks!
--
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