Tethys 2.0 uninstall apps issue

[shawncrawley]

I'm trying to migrate an existing app to Tethys 2.0. This mainly includes updating my current usage of persistent stores to the app_settings style. Anyway, I installed the app so I could troubleshoot where it breaks, and at this point it is breaking with this error:

File "/home/shawn/tethysdev/tethysapp-citywater/tethysapp/epanet/model.py", line 21, in <module>

    db_engine = EpanetApp.get_persistent_store_database('epanet')

  File "/home/shawn/tethys/src/tethys_apps/base/app_base.py", line 768, in get_persistent_store_database

    raise TethysAppSettingDoesNotExist('PersistentStoreDatabaseSetting named "{0}" does not exist.'.format(name))

tethys_apps.exceptions.TethysAppSettingDoesNotExist: PersistentStoreDatabaseSetting named "epanet" does not exist.

This is expected, since I haven't gone into the admin setting interface yet to setup these connections and plug them in. However, the server will not even start due to this error, thus preventing me from fixing it. I did the natural thing and attempted to uninstall the app, but it looks like the "tethys uninstall" command calls the app harvester for some reason, and so this command is breaking on the same error. This doesn't seem like a very good idea: having to have bug free code before you can uninstall an app. Am I missing something here?

[alansnow21]

I agree that we need to rethink this. I have run into the same problem.

[Scott Christensen]

A few of thoughts that will hopefully be helpful:

1. In order to install/uninstall your app currently you need to remove any global imports of your persistent store settings. Only import those settings within a function. The new 'as_session_maker' option should make that fairly reasonable (@alansnow21 or @swainn could explain/help with that better than I could). 
2. The plan is to catch the settings does not exist error and have it log a warning instead of it raising an error. That should prevent this situation from happening. I don't remember if this was going to make it into 2.0, but maybe we had better make sure that it does.
3. Neither of the previous thoughts really solve the heart of the problem, as you've pointed out, that if, for whatever reason, an app has buggy code that shouldn't prevent it from being uninstalled. We'll have to discuss that soon and find a way to resolve.

On Wed, Jun 14, 2017 at 6:47 PM alansnow21 <alans...@gmail.com> wrote:

I agree that we need to rethink this. I have run into the same problem.

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Scott D. Christensen, PhD

Research Civil Engineer

Information Technology Laboratory  

US Army Corps of Engineers

 

[Prasanna dahal]

I was also trying to migrate my app from Tethys 1.x to 2, and ran into same issue. Could not uninstall until I saw this suggestions from @sdc50. I wanted to share the experience- I had a few more syntax errors going from Tethys 1 to 2 which prevented uninstall, hence needed to remove almost all the imports- not just the global imports of my persistent store settings. Basically commented all the global imports (had issues with sdk.gizmos), and that was able to successfully uninstall after that.

Thanks,

Prasanna Dahal

Graduate Research Assistant

UWRL, Utah State University