Todo Dicts

We don’t have any todo items to show. Let’s use some handy PyCharm machinery as we implement this: more Code Intentions, Quick Documentation, and Reformat Code.

Source for this step | View video/audio walkthrough

Steps

  1. In models.py, replace pass with the following as the first line in populate_todos (remembering to use autocomplete on .append):

    todos.append({'id': 1, 'title': 'First'})

  2. Shift-F10 to re-run models.py and confirm that it prints that dictionary. (macOS: Ctrl-R)

  3. Change from a dictionary literal to dictionary constructor by clicking in the dictionary, typing Alt-Enter, and choosing Convert dict literal to dict constructor. It should now match:

    todos.append(dict(id=1, title='First'))

  4. Confirm all is well with a Shift-F10 re-run. (macOS: Ctrl-R)

  5. Change the last line in the main block, the print, to print the first todo’s id with a formatted string:

    print('Todo {todo_id}'.format(todo_id=todos[0]['id']))

  6. Re-run (Shift-F10). It should now show Todo 1 in the output. (macOS: Ctrl-R)

  7. How does Python’s format string method work? Click on .format and choose View -> Quick Definition from the PyCharm menu.

  8. Do the same with View -> Quick Definition and View -> External Documentation. (The latter has a mis-fire.)

  9. Press Ctrl-Alt-L to Reformat Code, if PyCharm shows any PEP8 style warnings.

  10. Your models.py should match the following:

    models.py in Todo Dicts
    todos = []


def populate_todos():
    todos.append(dict(id=1, title='First'))


if __name__ == '__main__':
    populate_todos()
    print('Todo {todo_id}'.format(todo_id=todos[0]['id']))

Analysis

In this small step we emphasize PyCharm automation:

  • Code Intentions. Put your cursor somewhere, press Alt-Enter, and let PyCharm suggest some things it can do for you.
  • Help Lookup. You’re not always going to remember everything about Python or some framework. PyCharm gives you two inline (non-distracting) ways and one external, full-page way to get context-sensitive information.

We also showed two things you’ll do over and over:

  • Shift-F10 to re-run the selected Run Configuration (macOS: Ctrl-R)
  • Ctrl-Alt-L to clean up your code with Reformat Code

Extra Credit

  1. How could we search for the Quick Definition action if we didn’t know where it was in the menu? How could this search tell us the keyboard shortcut?
  2. Does PEP8 get mad if you don’t have a blank line at the end of a file? Will PyCharm’s Reformat Code do the right thing for this?
  3. Can the Code Intention (Alt-Enter) convert back from a dict constructor to a dict literal?
  4. Can PyCharm link to external documentation for add-on packages such as SQLAlchemy?
  5. If you Reformat Code, and it misfires, can you undo it?