Home » Modeling » EMF » Deleting a non-containment reference to an object but not the associated object
| Deleting a non-containment reference to an object but not the associated object [message #416641] |
Fri, 08 February 2008 20:07  |
Eclipse User |
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Originally posted by: udaykabe.hotmail.com
I have several questions regarding the following EMF model:
I have 3 EClasses A, B and C. A has a multiplicity-many containment
reference to C, while B has a non-containment reference to C. Both A and B
display these references as children in my view. I can DND an instance of C
from A into B. Undo and Redo operations for the DND seem to work fine. My
questions are:
1. How do I delete a reference child in B without deleting the contained
reference in A. Currently the Delete action deletes the containment child
in A and retains the non-contained child reference in B. I did an override
of createRemoveCommand for both A and B, but it did not seem to get called,
hence the reason for this post.
2. How do I do both if the user so wishes, ie., delete all references as
well as the object that is referenced.
3. How does copy and paste differ from DND? Do the out-of-box
implementations of copy and paste work the same as drag and drop, ie, does
dragging and dropping an object of type C from A into B accomplish the same
thing as copying the same object form A and pasting it into B?
I should mention that at this point EClass B only has the multiplicity-many
reference feature and no other.
Thanx in advance.
Uday
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| Re: Deleting a non-containment reference to an object but not the associated object [message #416643 is a reply to message #416641] |
Fri, 08 February 2008 23:20  |
 David Steinberg
Messages: 489
Registered: July 2009 |
Senior Member |
|
|
Uday Kabe wrote:
> I have several questions regarding the following EMF model:
>
> I have 3 EClasses A, B and C. A has a multiplicity-many containment
> reference to C, while B has a non-containment reference to C. Both A and B
> display these references as children in my view. I can DND an instance of C
> from A into B. Undo and Redo operations for the DND seem to work fine. My
> questions are:
>
> 1. How do I delete a reference child in B without deleting the contained
> reference in A. Currently the Delete action deletes the containment child
> in A and retains the non-contained child reference in B. I did an override
> of createRemoveCommand for both A and B, but it did not seem to get called,
> hence the reason for this post.
Hi Uday,
The reason you're seeing this is because, by default, EMF.Edit is using
DeleteCommand, instead of RemoveCommand, to back the delete action. This
means that objects are totally deleted, removed from all references to
them. You can switch to using RemoveCommand simply by overriding
removeAllReferencesOnDelete() in your generated action bar contributor
class to return false. This will cause objects to be removed only from
the relevant reference that's being visualized in the tree.
Of course, this also means that, if you "delete" a C from its container,
its cross-references from any Bs will be left intact. This can leave you
with dangling references (i.e. cross-references to an object that is not
contained by anything).
> 2. How do I do both if the user so wishes, ie., delete all references as
> well as the object that is referenced.
The easiest thing to do would be to hook up two different actions:
a DeleteAction(false) to do removes, and a DeleteAction(true) to do true
deletes.
> 3. How does copy and paste differ from DND? Do the out-of-box
> implementations of copy and paste work the same as drag and drop, ie, does
> dragging and dropping an object of type C from A into B accomplish the same
> thing as copying the same object form A and pasting it into B?
Nope, they're completely different for a non-containment reference. By
default, a drag and drop does a "link" (notice the icon), which is
implemented simply by adding the object directly to the non-containment
reference.
Copy-paste actually creates a copy of the object on the clipboard and
then adds it to the reference. The result is a dangling reference.
Cheers,
Dave
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| Re: Deleting a non-containment reference to an object but not the associated object [message #417270 is a reply to message #416643] |
Tue, 04 March 2008 13:22 |
| Eclipse User |
|
|
|
Originally posted by: udaykabe.hotmail.com
Dave,
Thanks much for your response. I did read it as soon as you sent it, but I
got side-tracked by another pressing problem. I have walked through all the
RemoveCommand, DeleteCommand, and command creation code again.
In my case the, RemoveCommand is being created (removeAllReferences is
false), but the ItemProviderAdapter's getParent(target) returns the
target's (ie the object to be deleted) eContainer() as the parent which is
then set as the target's owner in the CommandParameter that is passed to the
RemoveCommand. Hence, the contained object gets deleted, and not the
non-containment reference. Is it truly possible to delete a selected
reference with the out-of-the-box delete mechanism? What am I missing?
Thanks again.
Uday
"Dave Steinberg" <davidms@ca.ibm.com> wrote in message
news:foio8f$6no$1@build.eclipse.org...
> Uday Kabe wrote:
>> I have several questions regarding the following EMF model:
>>
>> I have 3 EClasses A, B and C. A has a multiplicity-many containment
>> reference to C, while B has a non-containment reference to C. Both A and
>> B display these references as children in my view. I can DND an instance
>> of C from A into B. Undo and Redo operations for the DND seem to work
>> fine. My questions are:
>>
>> 1. How do I delete a reference child in B without deleting the contained
>> reference in A. Currently the Delete action deletes the containment
>> child in A and retains the non-contained child reference in B. I did an
>> override of createRemoveCommand for both A and B, but it did not seem to
>> get called, hence the reason for this post.
>
> Hi Uday,
>
> The reason you're seeing this is because, by default, EMF.Edit is using
> DeleteCommand, instead of RemoveCommand, to back the delete action. This
> means that objects are totally deleted, removed from all references to
> them. You can switch to using RemoveCommand simply by overriding
> removeAllReferencesOnDelete() in your generated action bar contributor
> class to return false. This will cause objects to be removed only from the
> relevant reference that's being visualized in the tree.
>
> Of course, this also means that, if you "delete" a C from its container,
> its cross-references from any Bs will be left intact. This can leave you
> with dangling references (i.e. cross-references to an object that is not
> contained by anything).
>
>> 2. How do I do both if the user so wishes, ie., delete all references as
>> well as the object that is referenced.
>
> The easiest thing to do would be to hook up two different actions:
> a DeleteAction(false) to do removes, and a DeleteAction(true) to do true
> deletes.
>
>> 3. How does copy and paste differ from DND? Do the out-of-box
>> implementations of copy and paste work the same as drag and drop, ie,
>> does dragging and dropping an object of type C from A into B accomplish
>> the same thing as copying the same object form A and pasting it into B?
>
> Nope, they're completely different for a non-containment reference. By
> default, a drag and drop does a "link" (notice the icon), which is
> implemented simply by adding the object directly to the non-containment
> reference.
>
> Copy-paste actually creates a copy of the object on the clipboard and then
> adds it to the reference. The result is a dangling reference.
>
> Cheers,
> Dave
|
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| Re: Deleting a non-containment reference to an object but not the associated object [message #417272 is a reply to message #417270] |
Tue, 04 March 2008 13:30 |
Ed Merks
Messages: 33142
Registered: July 2009 |
Senior Member |
|
|
This is a multi-part message in MIME format.
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Content-Transfer-Encoding: 7bit
Uday,
Have a look at the thread "Deleting child reference deletes referent?"
dated 2/25/2008 10:59 AM. The solution is to ensure you are using
wrappers to display the non-contained children...
Uday Kabe wrote:
> Dave,
>
> Thanks much for your response. I did read it as soon as you sent it, but I
> got side-tracked by another pressing problem. I have walked through all the
> RemoveCommand, DeleteCommand, and command creation code again.
>
> In my case the, RemoveCommand is being created (removeAllReferences is
> false), but the ItemProviderAdapter's getParent(target) returns the
> target's (ie the object to be deleted) eContainer() as the parent which is
> then set as the target's owner in the CommandParameter that is passed to the
> RemoveCommand. Hence, the contained object gets deleted, and not the
> non-containment reference. Is it truly possible to delete a selected
> reference with the out-of-the-box delete mechanism? What am I missing?
>
> Thanks again.
>
> Uday
>
>
> "Dave Steinberg" <davidms@ca.ibm.com> wrote in message
> news:foio8f$6no$1@build.eclipse.org...
>
>> Uday Kabe wrote:
>>
>>> I have several questions regarding the following EMF model:
>>>
>>> I have 3 EClasses A, B and C. A has a multiplicity-many containment
>>> reference to C, while B has a non-containment reference to C. Both A and
>>> B display these references as children in my view. I can DND an instance
>>> of C from A into B. Undo and Redo operations for the DND seem to work
>>> fine. My questions are:
>>>
>>> 1. How do I delete a reference child in B without deleting the contained
>>> reference in A. Currently the Delete action deletes the containment
>>> child in A and retains the non-contained child reference in B. I did an
>>> override of createRemoveCommand for both A and B, but it did not seem to
>>> get called, hence the reason for this post.
>>>
>> Hi Uday,
>>
>> The reason you're seeing this is because, by default, EMF.Edit is using
>> DeleteCommand, instead of RemoveCommand, to back the delete action. This
>> means that objects are totally deleted, removed from all references to
>> them. You can switch to using RemoveCommand simply by overriding
>> removeAllReferencesOnDelete() in your generated action bar contributor
>> class to return false. This will cause objects to be removed only from the
>> relevant reference that's being visualized in the tree.
>>
>> Of course, this also means that, if you "delete" a C from its container,
>> its cross-references from any Bs will be left intact. This can leave you
>> with dangling references (i.e. cross-references to an object that is not
>> contained by anything).
>>
>>
>>> 2. How do I do both if the user so wishes, ie., delete all references as
>>> well as the object that is referenced.
>>>
>> The easiest thing to do would be to hook up two different actions:
>> a DeleteAction(false) to do removes, and a DeleteAction(true) to do true
>> deletes.
>>
>>
>>> 3. How does copy and paste differ from DND? Do the out-of-box
>>> implementations of copy and paste work the same as drag and drop, ie,
>>> does dragging and dropping an object of type C from A into B accomplish
>>> the same thing as copying the same object form A and pasting it into B?
>>>
>> Nope, they're completely different for a non-containment reference. By
>> default, a drag and drop does a "link" (notice the icon), which is
>> implemented simply by adding the object directly to the non-containment
>> reference.
>>
>> Copy-paste actually creates a copy of the object on the clipboard and then
>> adds it to the reference. The result is a dangling reference.
>>
>> Cheers,
>> Dave
>>
>
>
>
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<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
Uday,<br>
<br>
Have a look at the thread "Deleting child reference deletes referent?"
dated 2/25/2008 10:59 AM. The solution is to ensure you are using
wrappers to display the non-contained children...<br>
<br>
<br>
Uday Kabe wrote:
<blockquote cite="mid:fqjif5$o5s$1@build.eclipse.org" type="cite">
<pre wrap="">Dave,
Thanks much for your response. I did read it as soon as you sent it, but I
got side-tracked by another pressing problem. I have walked through all the
RemoveCommand, DeleteCommand, and command creation code again.
In my case the, RemoveCommand is being created (removeAllReferences is
false), but the ItemProviderAdapter's getParent(target) returns the
target's (ie the object to be deleted) eContainer() as the parent which is
then set as the target's owner in the CommandParameter that is passed to the
RemoveCommand. Hence, the contained object gets deleted, and not the
non-containment reference. Is it truly possible to delete a selected
reference with the out-of-the-box delete mechanism? What am I missing?
Thanks again.
Uday
"Dave Steinberg" <a class="moz-txt-link-rfc2396E" href="mailto:davidms@ca.ibm.com"><davidms@ca.ibm.com></a> wrote in message
<a class="moz-txt-link-freetext" href="news:foio8f$6no$1@build.eclipse.org">news:foio8f$6no$1@build.eclipse.org</a>...
</pre>
<blockquote type="cite">
<pre wrap="">Uday Kabe wrote:
</pre>
<blockquote type="cite">
<pre wrap="">I have several questions regarding the following EMF model:
I have 3 EClasses A, B and C. A has a multiplicity-many containment
reference to C, while B has a non-containment reference to C. Both A and
B display these references as children in my view. I can DND an instance
of C from A into B. Undo and Redo operations for the DND seem to work
fine. My questions are:
1. How do I delete a reference child in B without deleting the contained
reference in A. Currently the Delete action deletes the containment
child in A and retains the non-contained child reference in B. I did an
override of createRemoveCommand for both A and B, but it did not seem to
get called, hence the reason for this post.
</pre>
</blockquote>
<pre wrap="">Hi Uday,
The reason you're seeing this is because, by default, EMF.Edit is using
DeleteCommand, instead of RemoveCommand, to back the delete action. This
means that objects are totally deleted, removed from all references to
them. You can switch to using RemoveCommand simply by overriding
removeAllReferencesOnDelete() in your generated action bar contributor
class to return false. This will cause objects to be removed only from the
relevant reference that's being visualized in the tree.
Of course, this also means that, if you "delete" a C from its container,
its cross-references from any Bs will be left intact. This can leave you
with dangling references (i.e. cross-references to an object that is not
contained by anything).
</pre>
<blockquote type="cite">
<pre wrap="">2. How do I do both if the user so wishes, ie., delete all references as
well as the object that is referenced.
</pre>
</blockquote>
<pre wrap="">The easiest thing to do would be to hook up two different actions:
a DeleteAction(false) to do removes, and a DeleteAction(true) to do true
deletes.
</pre>
<blockquote type="cite">
<pre wrap="">3. How does copy and paste differ from DND? Do the out-of-box
implementations of copy and paste work the same as drag and drop, ie,
does dragging and dropping an object of type C from A into B accomplish
the same thing as copying the same object form A and pasting it into B?
</pre>
</blockquote>
<pre wrap="">Nope, they're completely different for a non-containment reference. By
default, a drag and drop does a "link" (notice the icon), which is
implemented simply by adding the object directly to the non-containment
reference.
Copy-paste actually creates a copy of the object on the clipboard and then
adds it to the reference. The result is a dangling reference.
Cheers,
Dave
</pre>
</blockquote>
<pre wrap=""><!---->
</pre>
</blockquote>
<br>
</body>
</html>
--------------010106020904040008050402--
Ed Merks
Professional Support: https://www.macromodeling.com/
|
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| Re: Deleting a non-containment reference to an object but not the associated object [message #417273 is a reply to message #417272] |
Tue, 04 March 2008 13:51 |
| Eclipse User |
|
|
|
Originally posted by: udaykabe.hotmail.com
This is a multi-part message in MIME format.
------=_NextPart_000_005B_01C87DCC.80A29C40
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Ed,
Thanks so much. I was wondering where you went; I was somewhat dismayed =
to think that your term on this group might be done. You cannot imagine =
how thankful I am to your EMF team for the quick responses you deliver =
to the posts on your newsgroups.
I will check on that thread.
Thanks again.
"Ed Merks" <merks@ca.ibm.com> wrote in message =
news:fqjiua$vvb$1@build.eclipse.org...
Uday,
Have a look at the thread "Deleting child reference deletes referent?" =
dated 2/25/2008 10:59 AM. The solution is to ensure you are using =
wrappers to display the non-contained children...
Uday Kabe wrote:=20
Dave,
Thanks much for your response. I did read it as soon as you sent it, =
but I=20
got side-tracked by another pressing problem. I have walked through all =
the=20
RemoveCommand, DeleteCommand, and command creation code again.
In my case the, RemoveCommand is being created (removeAllReferences is=20
false), but the ItemProviderAdapter's getParent(target) returns the=20
target's (ie the object to be deleted) eContainer() as the parent which =
is=20
then set as the target's owner in the CommandParameter that is passed to =
the=20
RemoveCommand. Hence, the contained object gets deleted, and not the=20
non-containment reference. Is it truly possible to delete a selected=20
reference with the out-of-the-box delete mechanism? What am I =
missing?
Thanks again.
Uday
"Dave Steinberg" <davidms@ca.ibm.com> wrote in message=20
news:foio8f$6no$1@build.eclipse.org...
Uday Kabe wrote:
I have several questions regarding the following EMF model:
I have 3 EClasses A, B and C. A has a multiplicity-many containment=20
reference to C, while B has a non-containment reference to C. Both A =
and=20
B display these references as children in my view. I can DND an =
instance=20
of C from A into B. Undo and Redo operations for the DND seem to work=20
fine. My questions are:
1. How do I delete a reference child in B without deleting the =
contained=20
reference in A. Currently the Delete action deletes the containment=20
child in A and retains the non-contained child reference in B. I did an =
override of createRemoveCommand for both A and B, but it did not seem to =
get called, hence the reason for this post.
Hi Uday,
The reason you're seeing this is because, by default, EMF.Edit is using=20
DeleteCommand, instead of RemoveCommand, to back the delete action. This =
means that objects are totally deleted, removed from all references to=20
them. You can switch to using RemoveCommand simply by overriding=20
removeAllReferencesOnDelete() in your generated action bar contributor=20
class to return false. This will cause objects to be removed only from =
the=20
relevant reference that's being visualized in the tree.
Of course, this also means that, if you "delete" a C from its container, =
its cross-references from any Bs will be left intact. This can leave you =
with dangling references (i.e. cross-references to an object that is not =
contained by anything).
2. How do I do both if the user so wishes, ie., delete all =
references as=20
well as the object that is referenced.
The easiest thing to do would be to hook up two different actions:
a DeleteAction(false) to do removes, and a DeleteAction(true) to do true =
deletes.
3. How does copy and paste differ from DND? Do the out-of-box=20
implementations of copy and paste work the same as drag and drop, ie,=20
does dragging and dropping an object of type C from A into B accomplish=20
the same thing as copying the same object form A and pasting it into B?
Nope, they're completely different for a non-containment =
reference. By=20
default, a drag and drop does a "link" (notice the icon), which is=20
implemented simply by adding the object directly to the non-containment=20
reference.
Copy-paste actually creates a copy of the object on the clipboard and =
then=20
adds it to the reference. The result is a dangling reference.
Cheers,
Dave=20
=20
=20
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charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<META http-equiv=3DContent-Type =
content=3Dtext/html;charset=3DISO-8859-1>
<META content=3D"MSHTML 6.00.6000.16608" name=3DGENERATOR>
<STYLE></STYLE>
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<BODY text=3D#000000 bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>Ed,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Thanks so much. I was wondering =
where you=20
went; I was somewhat dismayed to think that your term on =
this=20
group might be done. You cannot imagine how thankful I =
am to=20
your EMF team for the quick responses you deliver to the posts on =
your=20
newsgroups.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I will check on that =
thread.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Thanks again.</FONT></DIV>
<BLOCKQUOTE=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV>"Ed Merks" <<A =
href=3D"mailto:merks@ca.ibm.com">merks@ca.ibm.com</A>>=20
wrote in message <A=20
=
href=3D"news:fqjiua$vvb$1@build.eclipse.org">news:fqjiua$vvb$1@build.ecli=
pse.org</A>...</DIV>Uday,<BR><BR>Have=20
a look at the thread "Deleting child reference deletes =
referent?" dated=20
2/25/2008 10:59 AM. The solution is to ensure you are using =
wrappers to=20
display the non-contained children...<BR><BR><BR>Uday Kabe wrote:=20
<BLOCKQUOTE cite=3Dmid:fqjif5$o5s$1@build.eclipse.org =
type=3D"cite"><PRE wrap=3D"">Dave,
Thanks much for your response. I did read it as soon as you sent it, =
but I=20
got side-tracked by another pressing problem. I have walked through all =
the=20
RemoveCommand, DeleteCommand, and command creation code again.
In my case the, RemoveCommand is being created (removeAllReferences is=20
false), but the ItemProviderAdapter's getParent(target) returns the=20
target's (ie the object to be deleted) eContainer() as the parent which =
is=20
then set as the target's owner in the CommandParameter that is passed to =
the=20
RemoveCommand. Hence, the contained object gets deleted, and not the=20
non-containment reference. Is it truly possible to delete a selected=20
reference with the out-of-the-box delete mechanism? What am I =
missing?
Thanks again.
Uday
"Dave Steinberg" <A class=3Dmoz-txt-link-rfc2396E =
href=3D"mailto:davidms@ca.ibm.com"><davidms@ca.ibm.com></A> wrote =
in message=20
<A class=3Dmoz-txt-link-freetext =
href=3D"news:foio8f$6no$1@build.eclipse.org">news:foio8f$6no$1@build.ecli=
pse.org</A>...
</PRE>
<BLOCKQUOTE type=3D"cite"><PRE wrap=3D"">Uday Kabe wrote:
</PRE>
<BLOCKQUOTE type=3D"cite"><PRE wrap=3D"">I have several questions =
regarding the following EMF model:
I have 3 EClasses A, B and C. A has a multiplicity-many containment=20
reference to C, while B has a non-containment reference to C. Both A =
and=20
B display these references as children in my view. I can DND an =
instance=20
of C from A into B. Undo and Redo operations for the DND seem to work=20
fine. My questions are:
1. How do I delete a reference child in B without deleting the =
contained=20
reference in A. Currently the Delete action deletes the containment=20
child in A and retains the non-contained child reference in B. I did an =
override of createRemoveCommand for both A and B, but it did not seem to =
get called, hence the reason for this post.
</PRE></BLOCKQUOTE><PRE wrap=3D"">Hi Uday,
The reason you're seeing this is because, by default, EMF.Edit is using=20
DeleteCommand, instead of RemoveCommand, to back the delete action. This =
means that objects are totally deleted, removed from all references to=20
them. You can switch to using RemoveCommand simply by overriding=20
removeAllReferencesOnDelete() in your generated action bar contributor=20
class to return false. This will cause objects to be removed only from =
the=20
relevant reference that's being visualized in the tree.
Of course, this also means that, if you "delete" a C from its container, =
its cross-references from any Bs will be left intact. This can leave you =
with dangling references (i.e. cross-references to an object that is not =
contained by anything).
</PRE>
<BLOCKQUOTE type=3D"cite"><PRE wrap=3D"">2. How do I do both if =
the user so wishes, ie., delete all references as=20
well as the object that is referenced.
</PRE></BLOCKQUOTE><PRE wrap=3D"">The easiest thing to do would be =
to hook up two different actions:
a DeleteAction(false) to do removes, and a DeleteAction(true) to do true =
deletes.
</PRE>
<BLOCKQUOTE type=3D"cite"><PRE wrap=3D"">3. How does copy and =
paste differ from DND? Do the out-of-box=20
implementations of copy and paste work the same as drag and drop, ie,=20
does dragging and dropping an object of type C from A into B accomplish=20
the same thing as copying the same object form A and pasting it into B?
</PRE></BLOCKQUOTE><PRE wrap=3D"">Nope, they're completely =
different for a non-containment reference. By=20
default, a drag and drop does a "link" (notice the icon), which is=20
implemented simply by adding the object directly to the non-containment=20
reference.
Copy-paste actually creates a copy of the object on the clipboard and =
then=20
adds it to the reference. The result is a dangling reference.
Cheers,
Dave=20
</PRE></BLOCKQUOTE><PRE wrap=3D""><!---->
</PRE></BLOCKQUOTE><BR></BLOCKQUOTE></BODY></HTML>
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