Conditional messages for before/after copy/update

[farhaan-shamsee]

Actual Situation

Currently the message_before_update and similar messages gets printed on every copy or update.

There can be the case where I want some specific message to be printed when a condition is met. I think this is not possible currently.

Desired Situation

In my case, I have different versions of template. So when a user is updating from 1.0.0 to 2.0.0, I want a message to be printed, for example to take backup of a file, as it will be a breaking change.

But if the user is already on 2.0.0, and runs update to change some answers, then I do not want the same message to be displayed.

Or in short the update message should be displayed on the first update only of a particular template version.

Proposed solution

As a workaround for my use-case, I was trying to get the _copier_answers._commit value from the answers file and then apply some logic to check if the version of template was changing (as it will only change if I am updating to new template version). But it seems that the _commit value changes even before the update command gets executed. So I do not have any way of getting the previous value of _commit.

[pawamoy]

Sounds like migrations. You'd have a migration between v1 and v2 that does the file backup for you and prints a message.

[yajo]

It could be done with migrations, but in reality those run at the end of the update. However the feature request is to have messages at the beginning AFAICS.

[farhaan-shamsee]

Sounds like migrations. You'd have a migration between v1 and v2 that does the file backup for you and prints a message.

Yes, this can resolve/help in my use case but partially. As mentioned by @yajo , there can be some use cases where we want the messages to be printed before also.

[yajo]

Can't you just add a message like: "If you are doing a major version update, make sure to check the template change log."?

[farhaan-shamsee]

Yes, in fact this is what we are doing currently, redirecting them to our release notes. And also looking at the migrations as mentioned above.
I believe this fulfils our requirement.