Get path to newly created subproject before merge

[lhupfeldt]

I'm trying to have a templated file which can be "taken over" by the subproject user, and a corresponding example file which starts out the same. By "taken over" I mean that if any modification was made by the user, then any furher changes in the template file will be ignored, but as long as the file has not been modified in the subproject, it will be updated as normal. The reason for this is an automated update of subprojects where there is nobody to handle merge conflicts.
The example file will (should) never be modified in the subproject, so it will never cause conflicts.
I would like to avoid having two source files in the template which must be kept the same.
I thought I could achieve this with migration tasks and have been looking at https://copier.readthedocs.io/en/latest/updating/#how-the-update-works. However it seems impossible to copy the expanded templates before merge.

It seems that I would need a migration task call somehere in the middle of the large box?
Are the paths to the tmp directories exposed to tasks?

[yajo]

Sorry, that use case is not supported. 🫤

You can only decide between including updates for a file or not.

The hooks you ask for also don't exist AFAICR.

[lhupfeldt]

My scenario is quite difficult to implement without access to tmp directories and maybe that is not even enough, depending on the state of them when hooks are called. As I see it, it is possible with a duplicate file in the template or by doing a copy operation and comparing the expanded file with the one from the update operation, both not very appealing.
Would it be difficult to support it directly in copier?
I think this could be generally useful for anybody using copier in 'hands off' automation.

[yajo]

It is a very weird use of copier.

Usually you care or you don't care about updates on a file.

I would just use the skip if exists feature. So if the user wants to reset the file to the template default, just remove it and recopy. It will be reset. Otherwise or just ignores updates.

To be supported here we'd need to understand why is it required.

[lhupfeldt]

Using skip if exists is not really an option for us. We currently have about 50 projects where we instantiate subprojects from the same template. This is part of a completely automated flow. If we use skip if exists we drop updating for the 90% of users that never modify this file (many of them will not even know how the setup is done).
Would you be willing consider a skip if modified feature if you got a PR? (not promising that I will do it though :)

[yajo]

Yes, I'd review that and merge if it fits our standards 😊