Let settings determine which batch handler to use for vendor catalog views.

tailbone/views/batch.py

@@ -366,7 +366,15 @@ class BatchCrud(BaseCrud):
 
     def __init__(self, request):
         self.request = request
-        self.handler = self.batch_handler_class(config=self.request.rattail_config)
+        self.handler = self.get_handler()
+
+    def get_handler(self):
+        """
+        Returns a `BatchHandler` instance for the view.  Derived classes may
+        override this as needed.  The default is to create an instance of
+        :attr:`batch_handler_class`.
+        """
+        return self.batch_handler_class(self.request.rattail_config)
 
     def fieldset(self, model):
         """

tailbone/views/vendors/catalogs.py

@@ -27,10 +27,11 @@ Views for maintaining vendor catalogs
 from __future__ import unicode_literals
 
 from rattail.db import model
-from rattail.db.api import get_vendor
+from rattail.db.api import get_setting, get_vendor
 from rattail.db.batch.vendorcatalog import VendorCatalog, VendorCatalogRow
 from rattail.db.batch.vendorcatalog.handler import VendorCatalogHandler
 from rattail.vendors.catalogs import iter_catalog_parsers, require_catalog_parser
+from rattail.util import load_object
 
 import formalchemy
 
@@ -84,6 +85,24 @@ class VendorCatalogCrud(FileBatchCrud):
     flash = {'create': "New vendor catalog has been uploaded.",
              'delete': "Vendor catalog has been deleted."}
 
+    def get_handler(self):
+        """
+        Returns a `BatchHandler` instance for the view.
+
+        Derived classes may override this, but if you only need to replace the
+        handler (i.e. and not the view logic) then you can instead subclass
+        :class:`rattail.db.batch.vendorcatalog.handler.VendorCatalogHandler`
+        and create a setting named "rattail.batch.vendorcatalog.handler" in the
+        database, the value of which should be a spec string pointed at your
+        custom handler.
+        """
+        handler = get_setting(Session, 'rattail.batch.vendorcatalog.handler')
+        if handler:
+            handler = load_object(handler)(self.request.rattail_config)
+        if not handler:
+            handler = super(VendorCatalogCrud, self).get_handler()
+        return handler
+
     def configure_fieldset(self, fs):
         parsers = sorted(iter_catalog_parsers(), key=lambda p: p.display)
         parser_options = [(p.display, p.key) for p in parsers]