“Failed building wheel for psycopg2” - MacOSX using virtualenv and pip

Question

I\'m attempting to make a website with a few others for the first time, and have run into a weird error when trying to use Django/Python/VirtualEnv. I\'ve found solutions to

Answer 1

TDLR

If you aren't used to installing Python C-extensions, and psycopg2 isn't a core part of your work, try

pip install psycopg2-binary

Building Locally

psycopg2 is a C-extension, so it requires compilation when being installed by pip. The Build Prerequisites section of the docs explain what must be done to make installation via pip possible. In summary (for psycopg 2.8.5):

• a C compiler must be installed on the machine
• the Python header files must be installed
• the libpq header files must be installed
• the pg_config program must be installed (it usually comes with the libpq headers) and on $PATH.

With these prerequisites satisfied, pip install psycopg2 ought to succeed.

Installing pre-compiled wheels

Alternatively, pip can install pre-compiled binaries so that compilation (and the associated setup) is not required. They can be installed like this:

pip install psycopg2-binary

The docs note that

The psycopg2-binary package is meant for beginners to start playing with Python and PostgreSQL without the need to meet the build requirements.

but I would suggest that psycopg2-binary is often good enough for local development work if you are not using psycopg2 directly, but just as a dependency.

Concluding advice

Read the informative installation documentation, not only to overcome installation issues but also the impact of using the pre-compiled binaries in some scenarios.