petriflowLibrary 1.0.1

Import/Export library

Petriflow Library - A tool for parsing Petriflow files in Python

PetriflowLibrary is a library in the Python language for handling objects

in the Petriflow language. The main objective of the library is to import

and export Petriflow files to work more closely with these objects.

Who is it for?

PetriflowLibrary is very easy to use. If you are a student

or just need to get the contents of an XML document in Python to work with

data as objects, the library provides you convenient and flexible tools for

processing them. It also provides the option to import the file from the path

on the device or as a URL where the XML document is located. During this process,

the document is also validated, and if it is invalid, the library throws an error.

What can it do?

• import XML documents based on XSD

• modify XML documents (set, get, add, insert, replace)

• export modified XML documents using "pretty_print", which guarantees a tree-structured output document

• compatible with the latest version of Python 3

• fully tested using unittests

Most importantly, PetriflowLibrary will save you time and prevent you from getting parsing headaches.

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Install PetriflowLibrary

pip install petriflowLibrary

Get started

The following is an illustration of how to use the library:

Original XML file:

<data type="text">

    <id>text_0</id>

    <title>Meno</title>

</data>

Using Python to modify an XML file:

from petriflow import *



file_object = open("../resources/hypouver.xml", encoding="utf-8")

doc = import_xml(file_object)

file_object.close()



doc.data[0].set_encryption(encryption())

doc.data[0].encryption.set_valueOf_(True)



export_xml(doc, "C:/Users/peterkox/Downloads/output.xml")

Output XML file:

<data type="text">

    <id>text_0</id>

    <title>Meno</title>

    <encryption>true</encryption>

</data>

Note that we opened the file with the open() method and set the encoding to utf-8.

This method has the default encoding set to None, so it would encode unicode

characters incorrectly. Also note that we use dot notation to access individual

objects. Be careful with arrays, because autocomplete does not work with them,

so you need to know exactly what you want to type or access.

You can find it here:

• Main implementation

• Tests - automated tests using unittest

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Method code explanation

import_xml

• The first step is parsing itself. The method takes an argument representing

the path to the file and additionally has one optional argument representing

the type of the parser itself. If this argument is not specified, the method

automatically sets the standard parser, which is the so-called ETCompatXMLParser().

It is flexible and moreover compatible for ElementTree from lxml and also takes

care of what would be done by the parser provided by the

xml.etree.ElementTree module in alternative case. After parsing, the ElementTree

object is stored in the doc variable. The second step is validation using a method

created by us, which ensures from the beginning that no further work is done with

the faulty document. Before saving the namespace from the XML document, we get

the root element using the doc.getroot() method and the root tag using a separate

get_root_tag() method. If the root element class is not found, it will be

set to "document" as the default top layer of the document. The factory() method

finally creates and returns an object instance of the given root element, which

we will then directly work with when modifying the document as a whole. Finally,

with the build() method, we fill this object with XML document data. Method returns

"document" object.

export_xml

• Based on the root element object, which is the first argument of the method,

we will create an ElementTree, which we will then store in the location

specified in advance by the second argument of the method.

validate_doc

• The method first gets the absolute path to the library and then uses it to

create a relative path to the XSD available in the library's resources folder.

By subsequently using a relative path, the method can load the XSD file.

By default, we insert the loaded schema into the ElementTree using the XMLSchema()

method, which returns an object on which we can now call the validate() method.

If it is not a valid XML document, the condition catches the case, prints an error

and terminates the program.

set_namespace_defs

• The logic builds on iteration through the elements and searches for the root

element based on obtaining the root when parsing the XML document. We then go

through each key:value and insert them in a specific format. The keys are written

in the form {standard-namespace-prefix}noNamespaceSchemaLocation, so we need

to extract the attribute name from it, then we can easily get the value from

the key. Finally, we create a dictionary where the key is the root tag and the

value is our entire namespace, we clean the contents of the variable

GenerateDSNamespaceDefs_ and fill it with a new dictionary.

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Contact the author

Questions about code are best asked on discord or in the issues.

-- Peter