Beginner Developer: Python extension

HQ_Best_QH · October 16, 2025, 3:07pm

Hi, im trying to create a python extension,
i tried following both java and python tutorials with no luck in the last few days - in the end node could not be recognised and ive decided to just give up on using IDE - just don’t want to burn any more time playing with a setup, just want to get on with the logic even if debugging is gonna be harder.

My question is - could someone advise what would be bare minimu files needed in \AppData\Local\Programs\KNIME\plugins\ path to have a plugin with one input, one output and python pandas in the middle? I just want to modify .py file logic, change icon and node name.

Are there any simple existing python nodes that i could use as a starting point that you could recommend looking at?

MartinDDDD · October 16, 2025, 5:37pm

Hey there,

good luck with developing your extension.

Not enough time in the day to give you a walk through right now, but what I can offer is for you to check out my finance extension on github:

Node .py files are located in /src/nodes/…/

A simple one to check out could be the pmt function:

github.com/DataNautics-GmbH/DataNautics-KNIME-Finance-Extension

src/nodes/ExcelLoanFuncs/pmt.py

main

import knime.extension as knext
import numpy as np
import numpy_financial as npf
from nodes.utils.category import loan_functions_category


@knext.node(name="PMT", 
            node_type=knext.NodeType.MANIPULATOR,
            icon_path="src\icons\PMT.png",
            category=loan_functions_category)
@knext.input_table(name="Input Data", description="Table containing rate, nper, and pv values")
@knext.output_table(name="PMT Results", description="Table with calculated PMT values")
class PMTNode:
    """Calculates the periodic payment required to amortize a loan with constant payments and a constant interest rate.
    
    # PMT Node
    
    This node implements Excel's **PMT** function to calculate the fixed payment amount required to fully amortize a loan over a specified number of periods at a constant interest rate.
    
    ## Input Requirements

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Also moving this to the python extension development section - maybe someone from the KNIME team can pick this up!

HQ_Best_QH · October 17, 2025, 9:38am

Thank you for sharing! Another question - if i download files and drop them into dropins or plugins, nodes should become available after restarting knime?
I cannot seem to find them in knime…

Folder path should be right:
AppData\Local\Programs\KNIME\plugins\DataNautics-KNIME-Finance-Extension-main
in there i have all loose files and flders: src, config.yml, knime.yml etc.

I have set Preferences → Knime modern UI → Nodes included: All nodes
Is there a setting that would prevent community nodes from being loaded?

MartinDDDD · October 17, 2025, 9:59am

If you want to get inspiration on how to build a python extension then you can review the extension on GitHub.

I you want to use the extension you best install it from the relevant update site. Go to Preferences => Install/Update => Available Software Sites and make sure that community contributions as per below is active and potentially reload it

Then go to Menu => Install Extensions and in the pop up search for Fin. Then Select Financial Operations and FP&A extension and click next, accept licenses etc. until it installs.

Once it has finished installing after a restart you should find the nodes in your node repository

HQ_Best_QH · October 17, 2025, 10:38am

Enabled and reloaded community contributions, but its strange - seems to be missing financial ops:

MartinDDDD · October 17, 2025, 11:00am

Which version are you on? I think I first released it for v5.7 (may be able to built it for 5.5+ later on).

HQ_Best_QH · October 17, 2025, 12:14pm

5.5.2 - that explains it, thanks