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Item6090: Past revisions of topic show current versions of images

Priority: Enhancement
Current State: Proposal Required
Released In: n/a
Target Release: n/a
Applies To: Engine
Component: TopicAttachment
Reported By: TWiki:Main.VickiBrown
Waiting For:
Last Change By: GeorgeClark
If I create version 1 of a TWiki topic and attach version 1 of an image, TWiki sees that, by default, as %ATTACHURL%/image.gif.

Sometime later, in version 2 of the document, I update the image to version 2 as well. Version 1 of the image is archived in CVS.

But the link doesn't change; it's still %ATTACHURL%/image.gif. And if I look at my version history, all revisions will show %ATTACHURL%/image.gif.

This makes sense; after all, it's the text that was in the topic at the time of the revision. However, a user might justifiably expect to see the image that was attached to the topic at the time of the revision being viewed.

This is a difficult problem to solve. I think TWiki would need to save some sort of meta data for attachments that would remember the rev numbers. We may need to wait until there's some database backing for TWiki.

But I want to log the problem.

-- TWiki:Main/VickiBrown - 21 Oct 2008

That makes sense. What if within a text revision lifetime there is more than one revision of the image, and then both image and text change.. what image should I see if I request the revision where more than one image revision exists?

-- TWiki:Main.GilmarSantosJr - 22 Oct 2008

its much worse than this. rev 1 of the topic was built with the assumption that it would be seen with rev 12 of AnotherTopic.. and now rev 65 of it makes rev 1 look totally wrong.

I agree that there is a problem, but asking for rev1 of a topic I suspect is the wrong question - what you are suggesting is a much more useful UI - show me TopicX as it looked at 12:43am on the 12 of November 2001 that would be a question we could reasonably be expected to show correctly. (And that would be a useful Enhancment)

Vicki - thanks for asking about it smile

-- TWiki:Main.SvenDowideit - 22 Oct 2008

IIRC this also has been discussed once and awhile on codev. Svens proposal certainly would be an useful enhancement.

-- TWiki:Main.FranzJosefGigler - 22 Oct 2008

There are two new feature here.

  • The ability to see a topic based on a date. Ie. I give TWiki a topic name and a date and in return I get the revision of the topic I would have seen on that date. This would be a cool feature that many of my users have asked for. Especially if formatted searching could be date based. That is a feature proposal in itself and one that my imagination cannot see implemented efficiently without a DB storage.
  • The ability to see the image revisions that belong to the topic revision I am seeing.

The latter is for some more a bug than a feature request and also what Vicky reported.

When someone views an old topic revision and the topic contains images that have been updated then you see a mix of the old topic and the new image revision. TWiki will not serve the old version.

I see some problems resolving this.

  • Images of an older revision cannot be served by a simple ATTACHURL tag without letting TWiki "hack" the URL into a viewfile based URL when an old topic revision is viewed. Always using viewfile creates a performance problem because each image creates a new run of TWiki code on the server. A direct image URL adds nearly zero CPU load on the Apache server.
  • Current TML does not save any revision information in the topic itself. We would have to invent something new here.
  • If you have deleted the image in a later revision there is currently no way to see the old version even with viewfile. This happens often. I have seen it happen often.

So what we are looking for is perhaps a new way in future to store topic revisions in a way that they include the images.

This is not going to be trivial. But for sure a feature users are asking for.

-- TWiki:Main.KennethLavrsen - 24 Oct 2008

it is possible that this will actually be 'almost' easy - using url re-writing as per my DistributedServersPlugin, and then the viewfile redirection as per my TWikiCompatibility work - I need to convert this to a feature request!

ItemTemplate edit

Summary Past revisions of topic show current versions of images
ReportedBy TWiki:Main.VickiBrown
SVN Range TWiki-5.0.0, Sun, 05 Oct 2008, build 17588
AppliesTo Engine
Component TopicAttachment
Priority Enhancement
CurrentState Proposal Required
TargetRelease n/a
ReleasedIn n/a
Topic revision: r8 - 16 Mar 2011, GeorgeClark
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