This Python tutorial explains ElementTree.write() Method: Usage and Examples. Follow the example, inspect the output, and practise an input change so you understand the behavior rather than simply copying the syntax.
What This Feature Does
Write an ElementTree document to a stream or file.
ElementTree.write(file_or_filename, encoding=..., xml_declaration=...) serializes XML. Specify UTF-8 and whether an XML declaration is needed when creating files for other systems.
When to Use It
This technique belongs to XML and HTML processing. It is useful when the input, operation and expected outcome are known. Start with a small controlled example before integrating it into a larger workflow.
Step-by-Step Python Example
Read the code once before running it. Notice which values are inputs, which function or method performs the work, and whether the result is returned or stored by changing an existing object.
from io import BytesIO
import xml.etree.ElementTree as ElementTree
root = ElementTree.Element('root')
ElementTree.SubElement(root, 'message').text = 'Hello'
output_stream = BytesIO()
ElementTree.ElementTree(root).write(output_stream, encoding='utf-8', xml_declaration=True)
print(b'<?xml' in output_stream.getvalue())Understanding the Code
- First, the imports make io, xml.etree.ElementTree available. They provide the filesystem, data or standard-library functions used later.
- Find the call ElementTree.ElementTree(root).write(output_stream, encoding='utf-8', xml_declaration=True). Its parameters determine the specific operation demonstrated in the title.
- Its purpose is to write an elementtree document to a stream or file. Compare this description against the result printed by the program.
- The print() expressions display a checkable outcome. Print values and exception names are not substitutes for the program result itself.
Expected Output
TrueThe output is the observable result of the sample operation. Compare its value and type with the explanation, not just whether the program runs.
Important Details and Edge Cases
Write a document containing escaped ampersands and read it back.
Decoding a valid file format does not automatically validate the meaning of its data. Confirm expected keys, types, permitted values and resource limits before using externally supplied content.
Practice: Try It Yourself
Set short_empty_elements appropriately for consumers with strict formatting requirements.
Begin by copying the example into a separate practice file. Change one input at a time, run it again, and describe why the result changed. If the exercise writes or deletes files, keep it inside a temporary test folder.
Official Python Documentation
For the complete reference, see the Python standard library documentation.
Common Beginner Mistakes
- Assuming ElementTree.write() returns XML text instead of writing it to a destination.
- Write a document containing escaped ampersands and read it back.
- Decoding a valid file format does not automatically validate the meaning of its data. Confirm expected keys, types, permitted values and resource limits before using externally supplied content.
Key Takeaways
- Write an ElementTree document to a stream or file.
- ElementTree.write(file_or_filename, encoding=..., xml_declaration=...) serializes XML. Specify UTF-8 and whether an XML declaration is needed when creating files for other systems.
- Avoid this common pitfall: Assuming ElementTree.write() returns XML text instead of writing it to a destination.