jerinisready · February 2, 2022 05:29 · Feb 2, 2022
diff --git a/django_model_to_csv.py b/django_model_to_csv.py
@@ -0,0 +1,104 @@
+import csv
+from collections import defaultdict
+
+from django.db.models import Prefetch
+from django.utils.datetime_safe import datetime
+
+
+class Property(models.Model):
+    # id = ...           # primary key in model
+    pass
+
+
+class SubProperty(models.Model):
+    # id = ...           # primary key in model
+    # property = Property()
+    ## property_id = Property.id
+    pass
+
+
+class GetDataAsCSV(object):
+    # defined values
+    _prop_pk_field = 'id'             # the primary_key_field_name in property model ; ie Property.pk is 'id'
+                                      # the SubProperty.pk in property model should be _prop_pk_field; SubProperty.pk = 'id'
+    _prop_field_name = 'property'     # the property field name in sub-property model
+    _file_name = None
+
+    # required vars
+    _fields = []
+    _generated_data = None
+
+    @staticmethod
+    def get_property_ids():
+        return Property.objects.all().filter(
+            # if you have any global filter such as user specific properties or datetime or anything.
+        ).values_list('id', flat=True)
+
+    def get_properties(self, fields):
+        return Property.objects.all().filter(
+            # if you have any global filter such as user specific properties or datetime or anything.
+        ).values(self._prop_pk_field, *fields)
+
+    def get_sub_properties(self, property_id_set, fields):
+
+        filter_for_selected_props = {
+            self._prop_field_name: property_id_set
+        }
+
+        return SubProperty.objects.all().filter(
+            # if you have any global filter such as user specific properties or datetime or anything,
+        ).filter(**filter_for_selected_props).values(self._sub_prop_pk_field, self._prop_field_name, *fields)
+
+    @property
+    def file_name(self):
+        if self._file_name:
+            return self._file_name
+        now = datetime.now()
+        return "PropertyData_{day}_{month}_{year}_{timestamp}.csv".format(day=now.day, month=now.month, year=now.year, timestamp=now.timestamp())
+
+    def __init__(self, fields=None, file_name=None, prop_field_name=None):
+        self.properties_dataset = None
+        self.intermediate_data_form = None
+        self._fields = fields or []
+        self._prop_field_name = prop_field_name or self._prop_field_name
+        self.generate_data()
+
+    def generate_data(self):
+        if not self._fields: return
+        property_ids = self.get_property_ids()      # as values_list with flat=True
+        sub_properties_qs = self.get_sub_properties(property_ids, self._fields)
+
+        intermediate_data_form = defaultdict(list)
+        for sub_prop in sub_properties_qs:
+            prop_id = sub_prop[self._prop_field_name]
+            intermediate_data_form[prop_id].append(sub_prop)
+
+        self.intermediate_data_form = intermediate_data_form
+        self.properties_dataset = list(self.get_properties(fields=self._fields))
+        for prop in self.properties_dataset:
+            prop[self._prop_field_name] = ''
+	self.write_to_csv()
+
+    def write_to_csv(self):
+        outfile = self.file_name
+        ordered_fieldnames = [
+            self._prop_field_name,
+            *self._fields
+        ]
+        ordered_data = []
+        for prop in self.properties_dataset:
+            ordered_data.append(prop)
+            prop_id = prop['id']
+            if prop_id in self.intermediate_data_form:
+                ordered_data.extend(self.intermediate_data_form[prop_id])
+
+        with open(outfile, 'wb') as fou:
+            dw = csv.DictWriter(fou, delimiter=',', fieldnames=ordered_fieldnames)
+            dw.writeheader()
+            dw.writerows(ordered_data)
+
+
+
+if __name__ == "__main__":
+    GetDataAsCSV(fields=('field_01', 'field_02', 'field_03', 'field_04', ))
+