PythonFunction module - custom node for running python code on n8n.

run python code on n8n

PythonFunction node is used to run custom Python snippets to transform data or to implement some custom functionality that n8n does not support yet.

This node is pre-installed in the n8n-python docker image .

• Use n8n-python:latest-debian if you are planning to install heavy python packages such as numpy or pandas.
• Use n8n-python:latest for a more lightweight image.

Example using docker-compose.yml

You can mount a requirements.txt file to the container to install additional packages.

You can use the ExecuteCommand node to run pip install -r requirements.txt and the n8nTrigger node to trigger it after each restart.

This node requires the following dependencies to be installed in your environment:

• Python 3.6 or higher

   python3 --version # check output version

• python-fire

   # install fire
   pip install fire

If you’re running either by installing it globally or via PM2, make sure that you install n8n-nodes-python inside n8n. n8n will find the module and load it automatically.

If using docker, add the following line to your Dockerfile:

# Install n8n-nodes-python module
RUN cd /usr/local/lib/node_modules/n8n && npm install n8n-nodes-python

Read more about the installation process in the n8n documentation - Use the n8n-nodes-module in production .

This node receives ìtems and should return a list of items.

Example:

new_items = []
for item in items:
		item['newField'] = 'newValue'
		new_items.append(item)
return new_items # should return a list

The JSON attribute of each item is added and removed automatically. You can access the values directly without the json attribute. You don't need to put the item in a json attribute. it will be done automatically.

the items variable is a list of items that are passed to the function. They are directly accessible in the function.

Example:

print(items)
# > list
return items

You can specify environment variables to be used in the python code. The environment variables are accessible throw the env_vars dict.

Example:

print(env_vars)
print(env_vars.get('MY_VAR','default_value'))
# > dict

it is possible to write to the browser console by writing to stdout

Example:

print('Hello World')
# or
import sys
sys.stdout.write('Hello World')

• stderris used for passing data between nodes.

  • if exit code is 0, the node will be executed successfully and stderr represents the JSON representation of the output of the node
  • if exit code is not 0, the node fails and stderr represents the error message

• The json attribute of each item is added and removed automatically. (you can access and return the items directly without the json attribute)

Pull requests are welcome! For any bug reports, please create an issue.

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