Duplicate tickets when submitting with attachment

[Benjamin Lau]

I think how ever this was fixed may have introduced another error or related issue. I created a new ticket (#10293) and checked the option to upload an attachment. When I submitted the ticket it seems to have done it twice. Once with the original ticket number which has the attachment properly associated with it. And then a second time as #10294 without the attachment. I only noticed this because I had another ticket to submit about the same plugin and thought it was odd that the ticket number had jumped by two... since I didn't think the chance someone else submitted a ticket between my two was very high (and if so I was curious to see what was submitted). The second ticket didn't have an attachment so it doesn't seem to exhibit this issue.

Hope this helps.

[Ryan J Ollos]

#10296 was closed as a duplicate, so you've managed to demonstrate the problem while creating a ticket about the problem ;)

Unintentional creation of duplicate tickets is a long-standing and common issue on trac-hacks. However, I hadn't previously considered that it had to do with checking the box to submit an attachment on creation. If we look at recent instances of duplicate tickets, we find a number of duplicate tickets with sequential numbering, and which do not have attachments. Of course, we can never be sure whether the ticket creator checked that box but didn't add attachments.

Your theory is worth investigating, and it is nice that we now have a ticket for this issue. I saw this issue recently on my own Trac instance, which is running 0.12.3. comment:1:ticket:10256 provides an interesting hint at the possible problem.

[osimons]

So the request is received and input processed as new/updated ticket, but some error occurs after the fact when further processing (like email notifications) or when preparing to render the response. The user hits "Back" in the browser and submits the data again. Duplicates arise.

As we have no form of duplicate checking or other ways of detecting such double posts, this is really a general problem. It is much less likely to occur on newer Trac installations as the core throws less errors and generally handles them more gracefully, but I don't think any Trac will be immune.

I'm not sure there is much to be done about it. Upgrade to improve reliability, perhaps?

[Ryan J Ollos]

Most likely the issue will be resolved by ​trac:#10138, which I'm aiming to make part of the Trac 1.0.2 release.

[Ryan J Ollos]

Let's reopen the ticket if this isn't resolved after upgrading to Trac 1.0.2 (which includes the fix from ​trac:#10138).