QGIS Plugin: Creating a Plugin based on two scripts: where one script is dependent on another

To add 2 or more scripts (i.e. algorithms) you need to add the new module (i.e. algorithm_name_algorithm.py file) into your plugin directory and then reference it in the provider module (i.e. plugin_name_provider.py).

First you tell the provider module to access the new algorithm from a different module by entering a line such as this at the top of you script:

from .new_algorithm import NewAlgorithm

Here .new_algorithm would be the same as the file name (i.e. new_algorithm.py) and NewAlgorithm would be the name of the class inside that file.

Next go down to the loadAlgorithms function (i.e. def loadAlgorithms(self)) and add the line:

self.addAlgorithm(NewAlgorithm())

That's it. As long as all the names match up between the 2 files you should now have 2 algorithms in your plug-in.

An alternative, If you want to do as little coding as possible is to add the models directly to your plugin without converting them to scripts.

First copy all the model files (*.model3) to your plug-in directory.

Second open the provider module (plugin_name_provider.py) and add the following 2 lines to the top:

import os
from qgis.core import QgsProcessingModelAlgorithm

Lastly, go down to you loadAlgorithms function and add the following lines:

for dirpath, dirnames, files in os.walk(os.path.dirname(__file__)):
    for file_name in files:
        if file_name.lower().endswith('.model3'):
            alg = QgsProcessingModelAlgorithm()
            alg.fromFile(os.path.join(dirpath, file_name))
            self.addAlgorithm(alg)

This bit of code will cycle through your plug-in directory and any subdirectories and add all models that you have placed in there to your plug-in.