Connection provider and decorators in webclient

[atarkowska]

Due to the changes in #6387, Web should have one common strategy to create connection, keep it alive and retrieve in specific use cases. That is also related to decorators.

Tickets - DRAFT ONLY!!!

Examples of common functionality that exists (and could be moved to decorators) or that we might want to provide via decorators.

• Error handling, connection & redirect or error if json.

conn = None
    try:
        conn = kwargs["conn"]
    except:
        logger.error(traceback.format_exc())
        return handlerInternalError("Connection is not available. Please contact your administrator.")

• Would be nice to allow 3rd party developers to specify templates. E.g. as in webgateway

  def full_viewer(request, iid, server_id=None, _conn=None, **kwargs):
      ....
      template = kwargs.get('template', "webgateway/omero_image.html")
      ...etc.
  

• Also we have this a lot

      t = template_loader.get_template(template)
      c = Context(request,context)
      logger.debug('TEMPLATE: '+template)
      return HttpResponse(t.render(c))
  

# check menu
    menu = request.REQUEST.get("menu")
    if menu is not None:
        request.session['nav']['menu'] = menu
    else:
        menu = request.session['nav']['menu']
    # check view
    view = request.REQUEST.get("view")
    if view is not None:
        request.session['nav']['view'] = view
    else:
        view = request.session['nav']['view']

This line (or equivalent) is needed in many views

context['nav'] = request.session['nav']

Due to various parameters added to the request in isUserConnected

def sessionHelper(request):
    ...
    request.session['nav']={"blitz": blitz, "menu": "mydata", "view": "tree", "basket": 0, "experimenter":None}

def navHelper(request, conn):
    ...
    request.session['nav']['tab_links'] = links