.. _pip:

==========
pip
==========

.. attention:: Remember to check the correct :ref:`virtualenv` is activated before using pip to install software.


Installing apps
===================

There are various pip commands but the most useful is::

  pip install APP_NAME
  

Existing project
--------------------

If you have downloaded an existing project with a requirements file already, navigate to the folder containing the requirements file then::

  pip install -r requirements.txt


Uninstalling apps
=====================
  
To uninstall an app::

  pip uninstall APP_NAME

If you are developing a Django app and want to remove an app as well as tables it has created in the database::

  python manage.py sqlclear APP_NAME
  pip uninstall APP_NAME

.. note:: If that gives an error about migrations, delete the migrations folder then try again.


Updates
==============

To update your requirements list with the latest packages::

  pip freeze > requirements.txt

To update pip::

  pip install --upgrade pip

To find packages that are out of date::

  pip list --outdated --format=columns
  
To update a package::

  pip install -U APP_NAME


Requirements consideration
--------------------------

Some people recommend using ``pip freeze`` however there is a downside to it. All dependencies are listed as well which can make upgrading more complicated. Another approach is to manually add each package you install, with the version number, to ``requirements.txt``. When you update that package, any updated dependencies will also be installed. You can then manually edit the ``requirements.txt`` with the new version. This makes for a much cleaner list of requirements with upgrades simpler.