How to create multiple PlantUML diagrams from a python script?

Question

Scenario

Most instructions suggest you can generate PlantUML diagrams with python using: python -m plantuml example_diagram.txt. I wanted to create a python script that generates multiple PlantUML diagrams when it is created, such that I can instantly update a complete set of diagrams, without having to run multiple commands.

Example Files

The following files are used to generate the PlantUML graphs:

1. example_flow.txt with content:

' http://tonyballantyne.com/graphs.html#orgheadline19
' http://graphviz.org/doc/info/shapes.html

' Indicate the direction of the flowchart
left to right direction

' Give a block the variable name 'first' and define starting point as (*)
(*) --> "The first block" as first

first --> "A" as A
' Give the block a variable name s.t. you can just use its variable name in the next blocks
  --> "D" as D
first --> "B" as B
  --> D
first --> "C" as C
  --> D
  
' Define end point as (*)  
D --> (*)

2. Graphviz_example.txt with content:

' http://tonyballantyne.com/graphs.html#orgheadline19
' http://graphviz.org/doc/info/shapes.html

digraph summary{
    // initialize the variable blocks
    start [label="Start with a Node"]
    next [label="Choose your shape", shape=box]
    warning [label="Don't go overboard", color=Blue, fontcolor=Red,fontsize=24,style=filled, fillcolor=green,shape=octagon]
    end [label="Draw your graph!", shape=box, style=filled, fillcolor=yellow]

    // Indicate the direction of the flowchart
    rankdir=LR; // Rank direction left to right
    
    // Create the connections
    start->next
    start->warning 
    next->end [label="Getting Better...", fontcolor=darkblue]

}

Question

How can I create these diagrams from a single python script?

Answer 1

Generate for 2 files in the same directory

Create a python file named create_diagrams.py with content:

from plantuml import PlantUML
from os.path import abspath

# create a server object to call for your computations
server = PlantUML(url='http://www.plantuml.com/plantuml/img/',
                          basic_auth={},
                          form_auth={}, http_opts={}, request_opts={})

# Send and compile your diagram files to/with the PlantUML server
server.processes_file(abspath('./example_flow.txt'))
server.processes_file(abspath('./Graphviz_example.txt'))

And run it, for example in anaconda with python 3.6 with command: python create_diagrams.py.

Generate for all files in directory

One can also generate the diagrams for all .txt files in a directory named Diagrams with:

from plantuml import PlantUML
import os
from os.path import abspath

server = PlantUML(url='http://www.plantuml.com/plantuml/img/',
                          basic_auth={},
                          form_auth={}, http_opts={}, request_opts={})


# create subfolder name
diagram_dir = "./Diagrams"

# loop through all .txt files in the subfolder
for file in os.listdir(diagram_dir):
  filename = os.fsdecode(file)
  if filename.endswith(".txt"):
    # Call the PlantUML server on the .txt file
    server.processes_file(abspath(f'./Diagrams/{filename}'))

Notes

This implementation requires an active internet connection because your asking the PlantUML server to do the graph generation for you. To compile locally, you can also download the .jar file of the PlantUML software and call that from python to do your computation. A more detailed example of this is given in the question of this post.