Plugin / rest routing url / PicklingError -> Cache issue

[Bbillyben]

Hi,

I'm developping my 1st plugin
The plugin class inherit from PanelMixin, SettingsMixin, UrlsMixin, and InvenTreePlugin

UrlsMixin is dedicated here to some rest call to manage bootstrap table datas, the urls are defines as:

    def setup_urls(self):
        router = routers.DefaultRouter()

        router.register(r'track', SMPviews.SMPTrackViewSet, basename='track')
        return router.urls

the setting is pretty simple :

    SETTINGS = {
        'MONTH_FOLLOW': {
            'name': 'Number of Month to follow',
            'description': 'time scope in month to visualize from last entry',
            'default': 1,
            'validator': MinValueValidator(1),
        },
    }

The panel is added in StockLocation tab to display StokItemTrackin :

    def get_custom_panels(self, view, request):
        if isinstance(view, StockIndex) or isinstance(view, StockLocationDetail):
            
            if isinstance(view, StockLocationDetail):
                loc=view.get_object()
                urlTrac=reverse('plugin:stocktrack:track-location', kwargs={'loc': loc.pk})
            else:
                urlTrac=reverse('plugin:stocktrack:track-list')
                
            context={'dataUrl':urlTrac}
            
            tmpRend = render_to_string(template_name='stocktrackpanel/SMP_panel.html',context=context)

            panels = [
                {
                    # Simple panel without any actual content
                    'title': 'Stock Tracking',
                    'content': tmpRend,
                    'icon' : 'fa-thumbtack', 
                    'javascript_template': 'stocktrackpanel/SMP_panel.js'
                }
            ]
        return panels

the viewset inherit from APIDownloadMixin, rest_framework.viewsets.ModelViewSet:
with some action to filter, select location and sublocation items, ...

Every thing works fine in StockItem panel,

But I've got an error in Setting Panel :
_pickle.PicklingError: Can't pickle <function SMPTrackViewSet at 0x7fec3b80d280>: it's not the same object as plugins.StockTrackPanel_plugin.views.SMPTrackViewSet

It's linked to URL routes added and the cache system.

1/ If I route to a direct function rather than the viewset, Setting panel load fine
2/ if I disable cache system by adding in Inventree.setting.py :

CACHES = {
    'default': {
        'BACKEND': 'django.core.cache.backends.dummy.DummyCache',
    }
}

Setting panel load fine again.

I've read from gg that it could be due to some import sequence issues, that's why I've split my code in 2 files, but no effect.

=> Have you got any clue to help on that issue?

Versions :
Inventree Master last (1104e981a)
in docker dev environnement.

[matmair]

@Bbillyben can be connected to a bunch of things. I would suggest trying the following things:

• Turn of debugging - the caching system works a bit differently if caching is enabled; that causes problems sometimes
• use explicit function references or as_view pluggers - I honestly have never used viewsets with UrlMixins; once I need custom APIs I use AppMixin, there this works
• deepcopy the urlpatterns the router returns - that way they turn static

I am not really sure what you mean by `Setting panel? - could be the time of night here in Europe.
If you have a repo with the code I would be happy to take a look in the coming weeks, might be easier to debug that way.

[Bbillyben]

Thanks @matmair,

Yes we were at night here! I would mean Setting page (url /settings/).

I've spent a bit of my morning in testing.

1. Turning of debugging do not solve anything.
2. I've fast try to hard code url pattern, but viewset 'static' routing is a pain from my inexperience...
3. If i test with hard coded url, outside viewset, I it seems working => I should rewrite the whole view control.

I will post update as soon as I've move forward on it!

My code (from this night, absolutely no cleaning is available on github)

[matmair]

@Bbillyben the gh link 404s

[Bbillyben]

Rhaa excuse me, it was in private! I've just switch it

[Bbillyben]

I'm back with an ugly solution...........

Firstly : Observations

I went to a standard django.views.View, for my SMPTrackViewSet view class and route by linking .as_view() :

        SMP_URL=[
            path('track/', SMPviews.SMPTrackViewSet.as_view(), name='track-list'),
            path('track/location/<loc>/', SMPviews.SMPTrackViewSet.as_view(), name='track-location'),      
        ]

The overall process works fine, but I've got the same error in the 'Setting page' (inventreeURL/settings/)
error trace : ViewError.txt

So I test to code as basic as I can and code 'function based view', to route as :

SMP_URL=[
            path('track/', SMPviews.get_SMP_list, name='track-list'),
            path('track/location/<loc>/', get_SMP_location, name='track-location'),      
        ]

I can navigate to /settings/ without any issues

but when i'm trying to access urls, I've got the error :

Exception Type: AssertionError at /plugin/stocktrack/track/
Exception Value: Cannot apply DjangoModelPermissions on a view that does not set `.queryset` or have a `.get_queryset()` method.

error trace :FunctionViewError.txt

Solution

Set up a standard django.views.View
manage your get function.

Add a specific get_smth function to call the get, instanciating the class, eg:

    def get_track(request,*args, **kwargs):
        return SMPTrackViewSet().get(request, *args, **kwargs)

and route by :

        SMP_URL=[
            path('track/', SMPviews.SMPTrackViewSet.get_track, name='track-list'),
            path('track/location/<loc>/', SMPviews.SMPTrackViewSet.get_track, name='track-location'),      
        ]

That's Capillotracted !!!!

Some few test, and I will try to add the plugin in a prod environment!

[matmair]

@Bbillyben it might be easier to use AppMixin - interesting finds.

[Bbillyben]

@matmair , i've tested added AppMixin in the inherited class of the plugin.

I do not change anything else and I do have the PicklingError

What should I change in urls route definition in your opinion ?

[matmair]

@Bbillyben with the AppMixin you can basically just override the whole loading mechanism. I am a bit occupied with release preparations but I will try your repo once I am done with that.

[Bbillyben]

Thanks @matmair,
Ok I understand AppMixin will let a plugin define a whole app.
That would be overkill for my purpose here!
Thanks again for your answers. Don't spent much more time on it.
My main concern is a core js function override, as everything run smooth apparently, even in a prod environment!

I'm now trying to inherit from StockTrackingList to be more integrated, but I fail on the final request.is_ajax that redirect to the response instead of the JsonResponse I'm looking for, wip.

[matmair]

@Bbillyben I am currently rewriting the whole UI for #3901 - not sure how long investment in such a function would be helpful.