Hello experts! Could you please help. I have few views that return different querysets. my goal is to export current queryset to csv when user click button in browser.
Could you please recommend what is the best algorithm for doing this ? I already did all apart save query to csv only when button is clicked in browser.
Thank you in advance!
in your view
import csv
.....
output = []
response = HttpResponse (content_type='text/csv')
writer = csv.writer(response)
query_set = User.objects.select_related('profile').all()
#Header
writer.writerow(['First Name', 'Last Name', 'Full Name', 'Short Name'])
for user in query_set:
output.append([user.first_name, user.last_name, user.get_full_name, user.profile.short_name])
#CSV Data
writer.writerows(output)
return response
This works prefectly
If you are using classed based views, its really easy (this is the sort of task where they shine). Subclass the main view, override the template and content type.
Here is an example from one of my projects
views.py
class SavedSamplesView(ListView):
"""
This is the standard view returning HTML
"""
template_name = "SavedSamples.html"
model = Sample
context_object_name = "sample_list"
def get_queryset(self) :
slug = self.kwargs['submission_slug']
return Sample.objects.filter(submission__submission_slug=slug)
class SavedSamplesCsvView(SavedSamplesView):
"""
Subclass of above view, to produce a csv file
"""
template_name = 'SavedSamples.csv'
content_type = 'text/csv'
The template SavedSamples.cvs looks like this (the formatting to get the newline is a little ugly, but it works). The first line is the headers, remove that if you don't need it:
sample.id , sample.name , ... , comments
{% for sample in sample_list %}{{ sample.id }},{{ sample.name }},....,{{sample.comments}}
{% endfor %}
urls.py
url(r'^savedsamplescsv/(?P<submission_slug>[ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890\-_]+)/', views.SavedSamplesCsvView.as_view(), name='saved_samples_csv'),
I would use a link instead of a button, and style it as button.
I use the following snippet to generate a CSV for my queryset. It also includes related fields, that you can choose to ignore or use something else to serialize the data. ( Such as the default serializers that come with Django )
import csv
def dump_to_csv(model, qs):
"""
Takes in a Django queryset and spits out a CSV file.
"""
model = qs.model
writer = ''
headers = []
# Get standard fields
for field in model._meta.get_fields():
headers.append(field) if 'extra' not in field.name else None
writer += ','.join([field.name for field in headers])
writer += '\n'
for obj in qs:
row = []
for field in headers:
# Append all general fields
if field.get_internal_type() not in ['ForeignKey', 'ManyToManyField', 'OneToOneField']:
val = getattr(obj, field.name)
if callable(val):
val = val()
if type(val) == str:
val = val.encode("utf-8")
row.append(str(val))
# Append all fk fields
elif field.get_internal_type() in ['ForeignKey', 'OneToOneField']:
from django.core import serializers
import json
value = field.value_from_object(obj)
if value not in [None, ""]:
qs = field.remote_field.model.objects.filter(pk=value)
json_data = serializers.serialize("json", qs, fields=(field.name for field
in qs.first()._meta.get_fields() if
'extra' not in field.name))
json_data = [o['fields'] for o in json.loads(json_data)]
json_data = json.dumps(json_data)
json_data = json_data.replace(",", ";")
json_data = json_data.replace("\"", "'")
row.append(json_data)
else:
row.append("[]")
# Append all m2m fields
elif field.get_internal_type() in ['ManyToManyField']:
from django.core import serializers
import json
qs = getattr(obj, field.name).all()
json_data = serializers.serialize("json", qs)
json_data = [o['fields'] for o in json.loads(json_data)]
json_data = json.dumps(json_data)
json_data = json_data.replace(",", ";")
json_data = json_data.replace("\"", "'")
row.append(json_data)
writer += ','.join(row)
writer += '\n'
return writer
The reason I have this is because my use case requires me to have a JSON dump of each related object as well.
You can then return this in the response so:
file = dump_to_csv(qs.model, qs)
response = HttpResponse(file, content_type='text/csv')
response['Content-Disposition'] = u'attachment; filename="{0}"'.format('export.csv')
return response
Im late, but this could help someone... In my case, i create a submit btn in my template to post something like this:
import pandas
[...]
if request.method == 'POST':
[...]
dataset = "ur query here"
response = HttpResponse (content_type='text/csv')
response['Content-Disposition'] = 'attachment; filename="file.csv"'
pandas.DataFrame(dataset).to_csv(response)
return response
