Add support fo nullable foreign keys in CSVexport plugin

binder/plugins/views/csvexport.py

@@ -284,7 +284,12 @@ def get_datum(data, key, prefix=''):
 					else:
 						# Assume that we have a mapping now
 						fk_ids = data[head_key]
-						if type(fk_ids) != list:
+
+						if fk_ids is None:
+							# This case happens if we have a nullable foreign key that is null. Treat this as a many
+							# to one relation with no values. 
+							fk_ids = []
+						elif type(fk_ids) != list:
 							fk_ids = [fk_ids]
 
 						# if head_key not in key_mapping:

tests/plugins/test_csvexport.py

@@ -7,7 +7,7 @@
 from django.core.files import File
 from django.contrib.auth.models import User
 
-from ..testapp.models import Picture, Animal
+from ..testapp.models import Picture, Animal, PictureBook
 import csv
 import openpyxl
 
@@ -31,8 +31,10 @@ def setUp(self):
 
 		self.pictures = []
 
+		picture_book = PictureBook.objects.create(name='Holiday 2012')
+
 		for i in range(3):
-			picture = Picture(animal=animal)
+			picture = Picture(animal=animal, picture_book=picture_book)
 			file = CsvExportTest.temp_imagefile(50, 50, 'jpeg')
 			picture.file.save('picture.jpg', File(file), save=False)
 			picture.original_file.save('picture_copy.jpg', File(file), save=False)
@@ -48,6 +50,7 @@ def setUp(self):
 
 	def test_csv_download(self):
 		response = self.client.get('/picture/download_csv/')
+		print(response.content)
 		self.assertEqual(200, response.status_code)
 		response_data = csv.reader(io.StringIO(response.content.decode("utf-8")))
 
@@ -123,4 +126,25 @@ def test_context_aware_download_xlsx(self):
 			self.assertEqual(list(_values[2]),
 							 [self.pictures[1].id, str(self.pictures[1].animal_id), (self.pictures[1].id ** 2)])
 			self.assertEqual(list(_values[3]),
-							 [self.pictures[2].id, str(self.pictures[2].animal_id), (self.pictures[2].id ** 2)])
+							 [self.pictures[2].id, str(self.pictures[2].animal_id), (self.pictures[2].id ** 2)])
+
+	def test_none_foreign_key(self):
+		"""
+		If we have a relation that we have to include which is nullable, and we have a foreign key, we do not want the
+		csv export to crash. I.e. we also want for a picture to export the picture book name, even though not all pioctures
+		belong to a picture book
+		:return:
+		"""
+		self.pictures[0].picture_book = None
+		self.pictures[0].save()
+
+		response = self.client.get('/picture/download/')
+		self.assertEqual(200, response.status_code)
+		response_data = csv.reader(io.StringIO(response.content.decode("utf-8")))
+
+		data = list(response_data)
+		content = data[1:]
+
+		picture_books = [c[-1] for c in content]
+
+		self.assertEqual(['', 'Holiday 2012', 'Holiday 2012'], picture_books)

tests/testapp/models/__init__.py

@@ -9,7 +9,7 @@
 from .gate import Gate
 from .nickname import Nickname, NullableNickname
 from .lion import Lion
-from .picture import Picture
+from .picture import Picture, PictureBook
 from .zoo import Zoo
 from .zoo_employee import ZooEmployee
 from .city import City, CityState, PermanentCity

tests/testapp/models/picture.py

@@ -13,6 +13,18 @@ def delete_files(sender, instance=None, **kwargs):
 			except Exception:
 				pass
 
+
+class PictureBook(BinderModel):
+	"""
+	Sometimes customers like to commemorate their visit to the zoo. Of course there are always some shitty pictures that
+	we do not want in a picture album
+
+	"""
+
+	name = models.TextField()
+
+
+
 # At the website of the zoo there are some pictures of animals. This model links the picture to an animal.
 #
 # A picture has two files, the original uploaded file, and the modified file. This model is used for testing the
@@ -21,6 +33,7 @@ class Picture(BinderModel):
 	animal = models.ForeignKey('Animal', on_delete=models.CASCADE, related_name='picture')
 	file = models.ImageField(upload_to='floor-plans')
 	original_file = models.ImageField(upload_to='floor-plans')
+	picture_book = models.ForeignKey('PictureBook', on_delete=models.CASCADE, null=True, blank=True)
 
 	def __str__(self):
 		return 'picture %d: (Picture for animal %s)' % (self.pk or 0, self.animal.name)

tests/testapp/views/__init__.py

@@ -15,7 +15,7 @@
 from .gate import GateView
 from .lion import LionView
 from .nickname import NicknameView
-from .picture import PictureView
+from .picture import PictureView, PictureBookView
 from .user import UserView
 from .zoo import ZooView
 from .zoo_employee import ZooEmployeeView

tests/testapp/views/picture.py

@@ -3,16 +3,19 @@
 from binder.views import ModelView
 from binder.plugins.views import ImageView, CsvExportView
 
-from ..models import Picture
+from ..models import Picture, PictureBook
 
+class PictureBookView(ModelView):
+	model = PictureBook
 
 class PictureView(ModelView, ImageView, CsvExportView):
 	model = Picture
 	file_fields = ['file', 'original_file']
-	csv_settings = CsvExportView.CsvExportSettings(['animal'], [
+	csv_settings = CsvExportView.CsvExportSettings(['animal', 'picture_book'], [
 		('id', 'picture identifier'),
 		('animal.id', 'animal identifier'),
 		('id', 'squared picture identifier', lambda id, row, mapping: id**2),
+		('picture_book.name', 'Picturebook name')
 	])
 
 	@list_route(name='download_csv', methods=['GET'])