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DRF - Optimizing ModelViewSet queries

Using Django REST Framework for Model views there is always the issue of making duplicated queries without either prefetching the objects that will be accessed using the serializer and as such will lead to large number of queries being made to the database. This will help in optimizing the queryset used for the viewset by accessing the `_meta.fields` property of the serializer.

  • django
  • rest
  • rest-api
  • django-rest-framework
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Reset Postgres Sequences On Every Migrate

If you create alot of data via fixtures or by inserting the pk you will more than likely see alot of issues with the sequences being out in postgres when creating new records. Similar to: Foo with the pk(x) already exists This you have to fix by updating the postgres sequences to start at the correct number. The below will ensure after every migrate all sequences in predefined apps get reset.

  • postgres
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Generic CBV Permissions Helper

A permission helper that can be included in any generic CBV, it uses the model attribute of the class to load all the permissions and tests a user can perform that action before dispatching the view.

  • permissions
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inline forms for deeply nested models

I had a problem trying to display my model would have a foreign key and that model would have one too etc. Now there was a point I wanted to display the foreign keys of that field and display its fields and so on so forth. This pretty much expands the models by getting the base form that worked best for me. It is intended to only work alongside `Forms`. I haven't been able to get it to work with `ModelForm`. Example usage: forms.py class AddressForm(forms.Form): address_0 = forms.CharField(label="address", max_length=64) address_1 = forms.CharField( label="address cont'd", max_length=64, required=False) city = forms.CharField(max_length=64) state = USStateField(widget=USStateSelect) # django_localflavor_us.forms zip_code = USZipCodeField(label='zipcode') # django_localflavor_us.forms class ContactInfoForm(ForeignKeyFormMixin, forms.Form): name = forms.CharField(max_length=50) # address = model.ForeignKey(Address) # is a foreignkey in my model for Address phone = PhoneNumberField() # phonenumber_field.formfields (irrelevant could very well be forms.CharField) fax = PhoneNumberField(required=False) # phonenumber_field.formfields (irrelevant could very well be forms.CharField) email = forms.EmailField() foreign_keys = {'address': AddressForm} # foreign forms I want to introduce, key acts as a related_name def __init__(self, *args, **kwargs): super(ContactInfoForm, self).__init__(*args, **kwargs) class GenerationForm(ForeignKeyFormMixin, forms.Form): company = forms.CharField(max_length=50) code = forms.CharField(max_length=50, required=False) # contact = model.ForeignKey(ContactInfo) # is a foreignkey in my model for Contact # facility_address = model.ForeignKey(AddressForm, related_name='facility') # is a foreignkey in my model for Address # mailing_address = model.ForeignKey(AddressForm, related_name='mailing') # is a foreignkey in my model for Address foreign_keys = {'contact': ContactInfoForm, 'facility_address': AddressForm, 'mailing_address': AddressForm} view.py def generation_create_view(self): if self.request.method == 'POST': generator_form = GenerationForm(self.request.POST) if generator_form.is_valid(): cleaned_data = generator_form.cleaned_data (contact_address, created) = Address.objects.get_or_create( address_0=cleaned_data['contact_address_address_0'], # notice naming. trying to keep it orgnized as possible and reuse the "foreign key" you want to expand address_1=cleaned_data['contact_address_address_1'], city=cleaned_data['contact_address_city'].title(), state=cleaned_data['contact_address_state'][:2].upper(), zip_code=cleaned_data['contact_address_zip_code'], ) print contact_address (contact_info, created) = ContactInfo.objects.get_or_create( name=cleaned_data['contact_name'], address=contact_address, phone=cleaned_data['contact_fax'], email=cleaned_data['contact_email'], ) print contact_info # ... # (assuming you have created other models as above) (generator, created) = Generator.objects.get_or_create( contact=contact_info, company=cleaned_data['company'], facility_address=facility_address, mailing_address=mailing_address, code=cleaned_data['code'], ) return redirect('to some where') else: generator_form = GenerationForm() return render(request, 'generation_create.html', {'generator_form': generator_form, }) generator_form.html # assuming your standard form tags are setup `<form class="form"...>...`. you would access form and display as follows # I am using https://django-bootstrap.readthedocs.io/en/latest/index.html # to help display forms in bootstrap <p class="lead">Contact</p> {% bootstrap_form generator_form.contact %} # can also just do {{ generator_form.contact }} {% bootstrap_field generator_form.company %} # can also just do {{ generator_form.company }} <p class="lead">Facility:</p> {% bootstrap_form generator_form.facility_address %} # can also just do {{ generator_form.facility_address }} <p class="lead">Mailing:</p> {% bootstrap_form generator_form.mailing_address %} # can also just do {{ generator_form.mailing_address }} {% bootstrap_field generator_form.code %} # can also just do {{ generator_form.code }}

  • django
  • django-forms
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Do Not Escape Characters When Using dumpdata Command (Tested in Django 1.11)

Adds `--pretty` option to django `./manage.py dumpdata` command, which produces pretty utf-8 strings instead of ugly unicode-escaped s**t: > $ ./manage.py dumpdata app.pricingplan --indent=1 <pre> <code>[ { "pk": 1, "model": "app.pricingplan", "fields": { "name": "\u0411\u0430\u0437\u043e\u0432\u044b\u0439", } }, { "pk": 2, "model": "app.pricingplan", "fields": { "name": "\u0425\u0443\u044f\u0437\u043e\u0432\u044b\u0439", } } ] </code> </pre> > ./manage.py dumpdata app.pricingplan --indent=1 --pretty <pre> <code>[ { "pk": 1, "model": "app.pricingplan", "fields": { "name": "Базовый", } }, { "pk": 2, "model": "app.pricingplan", "fields": { "name": "Хуязовый", } } ] </code> </pre> Forked from an [old versions snippet](https://djangosnippets.org/snippets/2258/)

  • pretty
  • dumpdata
  • pretty-print
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CBV decorator from view function decorator

The Mixin approach for applying permissions to CBV views suffers from 3 issues: 1. you need to read the code to see what permissions are being applied to a View 2. multiple bits of disparate code required to specify, e.g., a simple permission check 3. permissions set on a base class are overridden by permission set on sub-class, unless special care is taken Here's a nice trick, using only built-in django machinery, apply a decorator intended to decorate a django view function to a CBV view. https://docs.djangoproject.com/en/1.11/topics/class-based-views/intro/#decorating-the-class This approach works for any function decorators with arguments - simply wrap it in a function that takes the same arguments: def my_cbv_decorator(*args **kwargs): return method_decorator(a_view_function_decorator(*args, **kwargs), name='dispatch') Use your new CBV decorator to decorate View sub-classes: @my_cbv_decorator('some_parameter') class MyCBView(django.views.generic.TemplateView): pass # dispatch method for this view is now wrapped by a_view_function_decorator Note: you can also pass decorator parameter directly to method_decorator, but wrapping it up like this makes the code read nicer.

  • view
  • decorator
  • permissions
  • cbv
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Convert tab indented string to dictionary

output: ``` {u'Ogrenci': [u'Tum okullar', u'Lisans', u'Onlisans', u'Yuksek Lisans / Doktora', u'Ingilizce Hazirlik'], u'Ogretim Elemani': [u'Tum okullar', u'Lisans', u'Onlisans', u'Yuksek Lisans / Doktora', u'Ingilizce Hazirlik']} ```

  • python
  • tab
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