Write lockfile before calling the "post_lock" hook

[lecardozo]

Is your feature request related to a problem? Please describe.

First, thanks for the nice work with PDM. 😄

I've been trying to come up with a way to pdm export a requirements.txt file every time an update to the lockfile happens. As some vulnerability scanning services and other CI tools do not yet support parsing/reading/interpreting pdm.lock files, this would allow us to adopt the PDM without compromising other parts of the workflow.

At first, we thought using PDM lifecycle hooks functionality would suffice. Something like

[tool.pdm.scripts]
post_lock = {shell = "pdm export -f requirements > requirements.txt"}

Unfortunately, that did not work, as the post_lock hook is called before the lockfile is written to the disk (snippet below)

pdm/pdm/cli/actions.py

Lines 120 to 125 in 7d9c0f3

	else:
	data = format_lockfile(project, mapping, dependencies)
	ui.echo(f"{termui.Emoji.LOCK} Lock successful")
	hooks.try_emit("post_lock", resolution=mapping, dry_run=dry_run)
	project.write_lockfile(data, write=not dry_run)

Describe the solution you'd like

Having the lockfile written to the disk before calling the post_lock hook would enable this functionality and make PDM's adoption easier for workflows that rely, at some point, on the standard requirements.txt file. 😃

[thiagoazeredo-quintoandar]

+1

[frostming]

I think this is a good issue for a new contributor 👍

[lecardozo]

Nice! I'll tackle that 😃