Add generic support for downloading list results as CSV

tailbone/templates/master/index.mako

@@ -69,6 +69,9 @@
 </%def>
 
 <%def name="context_menu_items()">
+  % if master.results_downloadable_csv and request.has_perm('{}.results_csv'.format(permission_prefix)):
+      <li>${h.link_to("Download results as CSV", url('{}.results_csv'.format(route_prefix)))}</li>
+  % endif
   % if master.creatable and request.has_perm('{}.create'.format(permission_prefix)):
       <li>${h.link_to("Create a new {}".format(model_title), url('{}.create'.format(route_prefix)))}</li>
   % endif

tailbone/views/master.py

@@ -40,6 +40,7 @@ from rattail.db.continuum import model_transaction_query
 from rattail.util import prettify
 from rattail.time import localtime #, make_utc
 from rattail.threads import Thread
+from rattail.csvutil import UnicodeDictWriter
 
 import formalchemy as fa
 from pyramid import httpexceptions
@@ -64,6 +65,7 @@ class MasterView(View):
     checkboxes = False
 
     listable = True
+    results_downloadable_csv = False
     creatable = True
     viewable = True
     editable = True
@@ -1384,6 +1386,46 @@ class MasterView(View):
         """
         return False
 
+    def results_csv(self):
+        """
+        Download current list results as CSV
+        """
+        results = self.get_effective_data()
+        fields = self.get_csv_fields()
+        data = six.StringIO()
+        writer = UnicodeDictWriter(data, fields)
+        writer.writeheader()
+        for obj in results:
+            writer.writerow(self.get_csv_row(obj, fields))
+        response = self.request.response
+        response.text = data.getvalue().decode('utf_8')
+        data.close()
+        response.content_length = len(response.text)
+        response.content_type = b'text/csv'
+        response.content_disposition = b'attachment; filename={}.csv'.format(self.get_grid_key())
+        return response
+
+    def get_csv_fields(self):
+        """
+        Return the list of fields to be written to CSV download.
+        """
+        fields = []
+        mapper = orm.class_mapper(self.model_class)
+        for prop in mapper.iterate_properties:
+            if isinstance(prop, orm.ColumnProperty):
+                fields.append(prop.key)
+        return fields
+
+    def get_csv_row(self, obj, fields):
+        """
+        Return a dict for use when writing the row's data to CSV download.
+        """
+        csvrow = {}
+        for field in fields:
+            value = getattr(obj, field)
+            csvrow[field] = '' if value is None else six.text_type(value)
+        return csvrow
+
     ##############################
     # CRUD Stuff
     ##############################
@@ -1799,6 +1841,14 @@ class MasterView(View):
                 config.add_view(cls, attr='mobile_index', route_name='mobile.{}'.format(route_prefix),
                                 permission='{}.list'.format(permission_prefix))
 
+            if cls.results_downloadable_csv:
+                config.add_tailbone_permission(permission_prefix, '{}.results_csv'.format(permission_prefix),
+                                               "Download {} as CSV".format(model_title_plural))
+                config.add_route('{}.results_csv'.format(route_prefix), '{}/csv'.format(url_prefix))
+                config.add_view(cls, attr='results_csv', route_name='{}.results_csv'.format(route_prefix),
+                                permission='{}.results_csv'.format(permission_prefix))
+
+
         # create
         if cls.creatable or cls.mobile_creatable:
             config.add_tailbone_permission(permission_prefix, '{}.create'.format(permission_prefix),