Add g.version algorithm

[AlisterH]

Description

This allows the user to check the details of the GRASS version that the GRASS processing provider is using. Useful for debugging.

[nyalldawson]

Ideally all these values would become outputs from this algorithm (so eg a model can adapt dynamically). Would you be willing to implement that?

[AlisterH]

I'm not sure I understand what you're suggesting. Whatever flags you use, g.version just produces one output. So if you want separate outputs, one for copyright message, one for citation options, etc, you would run it multiple times with different flags, which sounds like a good job for a processing model. But I'm not sure that it would be useful for adaptable models.

Surely for adaptable models all you need is to:

• parse the grass version number (which you get by running this with all the options unchecked), and/or
• parse the output of g.extension -a, which you get using g.extension.list algorithm that we committed not long ago.

My next thought was to look at a standard tool to check if a particular addon is available, and if not try to install it. I think that would be most useful.

[AlisterH]

Ideally perhaps what we should do for both g.version and g.extension.list is detect whether it is running as part of a model and if so store the results in an output variable rather than an output file. At some point I might try to see if it is possible to do that using the ext file, but it may be over my head.

[AlisterH]

I did spend quite some time looking at always saving the algorithm stdout to an output variable - I can just follow the existing code we're interacting with, but it's too complicated for me figure out the best way to do this.

[nyalldawson]

What I mean is that a html output is rather a dead end -- it's useful for a manual check of something, but restricts any use in automation (models or scripts). It would be better if we included the parsing in the algorithm so that the algorithm includes a string (or number) output value which is then super easy for use by these tools.

[AlisterH]

I've now committed changes to store the output in an output variable as well as to html. I've also changed the way outputs are printed, as I don't think pformat was acceptable for these outputs. This aspect of the implementation may be contentious, but it works.

[AlisterH]

With this it is easy enough to get the actual version number:

processing.run("grass7:g.version",{'html': 'grass_version_info.html', '-r': 0, '-e':0})['MESSAGES'].split()[1]

'7.8.7'

If we can get #53246 merged, a QGIS plugin could provide an algorithm description for e.g. r.stream.order, and simply do this to ensure the GRASS addon is installed:

alglist=processing.run("grass7:g.extension.list",{'-a': 'TRUE', 'html': 'addons_list.html'})['MESSAGES']
if 'r.stream.order' not in alglist.splitlines():
 processing.run("grass7:g.extension.manage",{'extension': 'r.stream.order', 'operation': 0})
{}

Since we don't provide any output to show whether an addon install or uninstall was successful, it might be wise for anyone doing this to then check again if it is actually installed...

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[AlisterH]

Bumping so the bot doesn't kill us.

I've now committed changes to store the output in an output variable as well as to html. I've also changed the way outputs are printed, as I don't think pformat was acceptable for these outputs. This aspect of the implementation may be contentious, but it works.

Also, I should note that there is something really inefficient about the code responsible for printing output messages to the algorithm dialog when we aren't creating an html output. Algorithms which produce a lot of output messages seem to speed up dramatically if generating an html output instead of printing to the algorithm dialog.

[github-actions[bot]]

The QGIS project highly values your contribution and would love to see this work merged! Unfortunately this PR has not had any activity in the last 14 days and is being automatically marked as "stale". If you think this pull request should be merged, please check

• that all unit tests are passing

• that all comments by reviewers have been addressed

• that there is enough information for reviewers, in particular

  • link to any issues which this pull request fixes

  • add a description of workflows which this pull request fixes

  • add screenshots if applicable

• that you have written unit tests where possible In case you should have any uncertainty, please leave a comment and we will be happy to help you proceed with this pull request. If there is no further activity on this pull request, it will be closed in a week.

[AlisterH]

.

[github-actions[bot]]

The QGIS project highly values your contribution and would love to see this work merged! Unfortunately this PR has not had any activity in the last 14 days and is being automatically marked as "stale". If you think this pull request should be merged, please check

• that all unit tests are passing

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• that you have written unit tests where possible In case you should have any uncertainty, please leave a comment and we will be happy to help you proceed with this pull request. If there is no further activity on this pull request, it will be closed in a week.

[github-actions[bot]]

The QGIS project highly values your contribution and would love to see this work merged! Unfortunately this PR has not had any activity in the last 14 days and is being automatically marked as "stale". If you think this pull request should be merged, please check

• that all unit tests are passing

• that all comments by reviewers have been addressed

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• that you have written unit tests where possible In case you should have any uncertainty, please leave a comment and we will be happy to help you proceed with this pull request. If there is no further activity on this pull request, it will be closed in a week.

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