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All snippets written in Python

2958 snippets

Snippet List

Database Routing by URL

An example of how to select the "default" database based on the request URL instead of the model. The basic idea is that the middleware `process_view` (or `process_request`) function sets some context from the URL into thread local storage, and `process_response` deletes it. In between, any database operation will call the router, which checks for this context and returns an appropriate database alias. In this snippet, it's assumed that any view in the system with a `cfg` keyword argument passed to it from the urlconf may be routed to a separate database. Take this urlconf for example: `url( r'^(?P<cfg>\w+)/account/$', 'views.account' )` The middleware and router will select a database whose alias is `<cfg>`, or "default" if none is listed in `settings.DATABASES`, all completely transparent to the view itself.

  • multidb database router url
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replace

Small example of how to write your own function. This is not available in Django. The function just replaces static text strings, regular expressions are not supported. The syntax is the same in SQLite, PostgreSQL, MySQL and Oracle.

  • text
  • replace
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Django chunked queryset iterator

The function slices a queryset into smaller querysets containing chunk_size objects and then yield them. It is used to avoid memory error when processing huge queryset, and also database error due to that the database pulls whole table at once. Concurrent database modification wouldn't make some entries repeated or skipped in this process.

  • django
  • python
  • database
  • queryset
  • iterator
  • memoryerror
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Pre-delete signal function for deleting files a model

This snippit is meant to be used with the pre_delete signal to delete any files associated with a model instance before the instance is deleted. It will search the model instance for fields that are subclasses of FieldFile, and then delete the corresponding files. As such, it will work with any model field that is a subclass of FileField.

  • remove
  • delete
  • signals
  • file
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CNPJ and CPF Validation for Models

The code was placed inside a helper file without using a class. The Django validator was not designed to work with validator classes, it would appear, so retrieving the value from the field proved to be a hassle. Just create a helper file, import it on your model, and use the validator in the standard way, as such: cnpj = models.CharField(unique=True, max_length=14, validators=[validate_CNPJ]) cpf = models.CharField(unique=True, max_length=14, validators=[validate_CPF])

  • model
  • validation
  • cnpj
  • cpf
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Simply Gravatar Templatetags

Simply Gravatar Templatetags, for example the name of this templatetag is: `templatetags/gravatar_tags.py`, this supported for Python2 or Python3.

  • django
  • image
  • templatetag
  • gravatar
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Template tag for stripping blank lines

When writing clean and easy-to-read templates, it's usually good to have structural template tags (e.g. {%for%}, {%if%}) alone on their own line with proper indentation. When such a template is rendered, the resulting HTML will have blank lines in place of the template tags. The leading blank space used for indentation is also intact. This template tag strips all empty and all-whitespace lines when rendering the template. Be careful not to apply it when not intended, e.g. when empty lines are wanted inside PRE tags.

  • template
  • html
  • strip
  • empty
  • blank
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CSVField for forms

FileField that checks that the file is a valid CSV and if specified in `expected_fieldnames` checks that the fields match exactly. The widget's `accept` parameter is set to accept csv, text and excel files. **TODO**: Validate the entirety of the CSV file, not just the headers. But this should be enough for most use cases, as checking the whole file could be computationally expensive for huge files. Example usage: people = CSVField(expected_fieldnames=['First Name', 'Last Name'])

  • forms
  • csv
  • field
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Form with one Formset example

As I was unable to find good examples to render an inlineformset together, I have posted this to Django snippets. The example shows a person's data together with the phonenumbers for that person. You can add, update and delete from this form.

  • form
  • inline
  • inlineformset
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A streamable "export to CSV" admin action

This snippets is inspired from [#2995](https://djangosnippets.org/snippets/2995/) but add the following: * get rid of `singledispatch` so we can use it with python2 without pip installing anything * streaming capabilities * the configuration params (header, fields, exclude...) are passed to the action function so we don't pollute the ModelAdmin class * fix utf8 issue in header

  • admin
  • export
  • csv
  • action
  • stream
  • export-csv
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Upload progress handler using cache framework

Ticket [#2070](http://code.djangoproject.com/ticket/2070) allows you to create your own file upload handlers. Here's an example handler that tracks a file's upload so you might display a progress meter after form submission. The snippet has two parts, the upload handler which tracks progress, and an upload_progress view used to report back to the browser. The upload handler uses [django's cache framework](http://www.djangoproject.com/documentation/cache/#the-low-level-cache-api) to store the data, which can then be retrieved by the view to send back to the browser. Note: Your form's http post request must have a query parameter (X-Progress-ID) sent along with it, which should contain a unique key to identify the upload. That key will also be sent with your ajax requests to the upload_progress view to retrieve the progress data. Setup: place the UploadProgressCachedHandler anywhere you like on the python path, and add to your settings.py: from django.conf import global_settings FILE_UPLOAD_HANDLERS = ('path.to.UploadProgressCachedHandler', ) + \ global_settings.FILE_UPLOAD_HANDLERS Set up the upload_progress view in any of your apps along with a corresponding entry in your urlconf. Here's some javascript example code to make the ajax requests and display the progress meter: <http://www.djangosnippets.org/snippets/679/> .

  • ajax
  • upload
  • progress
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