How to Create a File Upload Widget

Ajaxified file uploads are becoming de facto standard on the web. People want to see what they chose right after selecting a file instead of during submit of the form. Also if a form has validation errors, nobody wants to select the files again; the selection made should be still available in the form. Therefore, we need a solution that works by Ajax.

Luckily there is a Django app that can help. It's called django-ajax-uploader. Ajax uploader allows to create asynchronous single and multiple file uploads. All uploads are done into the uploads directory. In addition to the default functionality we need a possibility to show the preview of the temporary uploaded file, translate all messages and buttons, delete a file, move a file to a specific directory. I created a demo project which implements all that.

If you have a ModelForm with a FileField or ImageField, you need to not show this field in the form, but instead to add a hidden field for uploaded file path. When you choose a file, it will be uploaded to a temporary uploads directory and its path will be set in the hidden field. Also you need a hidden BooleanField for the state of file deletion. When you submit the form, the file will be moved from the temporary location to the correct location defined by the FileField or ImageField.

In the given example, besides django-ajax-uploader, I am using django-crispy-forms with bootstrap 3.0.0 support. It allows you to define the structure for the forms without creating repetitive HTML markup.

This would be a quick workflow of integrating ajax uploads into your project:

  • Install django-ajax-uploader and django-crispy-forms.
  • Put 'crispy_forms' and 'ajaxuploader' into INSTALLED_APPS.
  • Define CRISPY_TEMPLATE_PACK = 'bootstrap3' in the settings.
  • Define the url rule for ajax uploader
    from ajaxuploader.views import AjaxFileUploader
    uploader = AjaxFileUploader()
    urlpatterns = patterns('',
        # ...
        url(r'^helper/ajax-upload/$', uploader, name="ajax_uploader"),
        # ...
  • Create a form for your model which will have the ajax uploader.
  • Create the view which will handle your model and the chosen files and call it in your urls.
  • Create the template with appropriate javascript.

For a working example, please check image uploads project.


7 Powerful Features of PyCharm Editor I Enjoy Using Daily

Not long ago I noticed PyCharm editor's advertisement at Stack Overflow. As it was targeted to Python and Django developers, I got very curious. I tried the 30-day trial and after years of using jEdit, I finally switched to this new editor. Here is a list of features I am using every day and enjoy very much.

1. Separation by project

Every project can be opened in a different window. PyCharm supports and recognizes virtual environments and python paths. In addition, you can mark some directories as source roots to put them under python path. This is useful when you have some dynamical modifications of python paths. When you open a file of a project, it will be shown in a tab. You can split the window vertically or horizontally to organize tabs in groups. It is especially useful, when you need one file for reference (like models.py) when you are editing another file (like detail template). You can open additional files which don't belong to the project for reference too; their tabs will be marked in different color.

2. Syntax highlighting

This is the core feature of any coder's text editor. PyCharm supports syntax highlighting for all different formats that might be used in Django development: Python, HTML templates, CSS, JavaScript, SQL, and many more. As expected, Django template comments are grayed out. Anywhere in the comments "TODO:" and "FIXME:" lines are marked in different color. At the bottom of the editor you can browse through different files with those TODO lines. PyCharm also marks unused imports and undefined variables with the different color. This editor also encourages PEP 8 standard which makes the coding style uniform and easier to understand and modify for different developers.

3. Browsing

Like many other IDEs, PyCharm has a side-bar file browser in a tree structure. For the clear list view, the *.pyc files are not shown. Edited files are marked in different color. You can drag and drop files to different directories there. You can create new files or new python packages (directories with __init__.py files) quickly. Version control systems like Git, Subversion, Mercurial and CVS are supported (although for this purpose, I am using SourceTree). Also one feature I like is "Scroll from Source" which scrolls and activates the file of the active tab. This is very useful when you need to open another file of the same Django app. By middle-clicking on a variable/class/function, you get to the definition/implementation of it. By ⌘⇧O you can search for specific file. Analogously by ⌘O you can go to specific class implementation. When you have simple views, you can go from the view to the template by clicking on an icon and back (unfortunately, this didn't work in a more complex situation, where I used wrapping view functions).

4. Autocompletion

PyCharm tracks python paths and autocompletes almost everywhere: variables, classes, or functions defined or imported in the current file, imports themselves, Django templates, Django shell, Django management commands. Just don't forget to fire Ctrl + Space for autocompletion.

5. Editing shortcuts

Different shortcuts make the coding faster. Press ⌥→ to move the cursor right by one word. Press ⌥⇧→ to select one word from the right. Press ⌥↑ to select one block of code (multiple times to select containing blocks, e.g. from method declaration to class). Press ⇥ to indent the block of code or ⇧⇥ to unindent it. Press ⌘/ to comment out or uncomment a block of code. Press ⌘R to activate the replace dialog. (These where examples of keyboard shortcuts on Mac OS X. Shortcuts on Windows and Linux will/may differ).

6. Code refactoring.

PyCharm has a powerful feature of renaming classes, functions, variables, or modules. I tried it a couple of times in straightforward situations, but I am still a little bit suspicious about its accuracy for large projects. Although it is worth mentioning that in complex situations it shows you the occurrences of classes, functions, variables, or modules in a list for you to confirm.

7. Django management commands

Running schema migration previously required a lot of typing in the Terminal, i.e. changing the directory to the specific virtual environment, activating the virtual environment, changing directory to Django project, running

python manage.py schemamigration appname modificationdone --auto
Now it is as fast as pressing ⌥R, typing "sc", pressing ⇧⏎, typing "appname modificationdone --auto", pressing ⏎ just in the PyCharm IDE. Running development server or restarting can now be done just with one click. Django shell can also be used from within the IDE. So you don't get distracted by different windows and user interfaces while developing.

I am still quite new to PyCharm and I am discovering new useful features every day. In my opinion, the price of PyCharm is worth every Euro, because my coding, I would say, is now 30 to 40% more effective. Finally, there is some official video introduction to the editor from the developers "JetBrains":