Writing DOCX Files with LdmDocxWriter

LdmDocxWriter converts a light_document_model.Document (LDM) object into a DOCX file. It is the write counterpart to DocumentReader, which reads DOCX files and exposes them as an LDM tree. Together they form a round-trip pipeline: DocumentReader in, LdmDocxWriter out.

Prerequisites

Requirement	Detail
Python	3.9 or later
Package	`aspose-words-foss` (MIT-licensed)
Input	A `light_document_model.Document` instance

pip install aspose-words-foss

Write to a File Path

LdmDocxWriter.write(doc, output_path) serialises the LDM document to a DOCX file at the given path. If the path’s parent directory does not exist the call will raise FileNotFoundError.

from aspose.words_foss import DocumentReader, LdmDocxWriter

# Load a DOCX and obtain its LDM representation
reader = DocumentReader()
reader.load_file("input/original.docx")
ldm_doc = reader.to_light_document()

# Write the LDM document back to a DOCX file
writer = LdmDocxWriter()
writer.write(ldm_doc, "output/result.docx")
print("Written to output/result.docx")

Write to Bytes (In-Memory Output)

LdmDocxWriter.write_to_bytes(doc) returns the DOCX content as a bytes object. Use this when you need to send the file over a network, store it in a database, or avoid writing to the filesystem entirely.

from aspose.words_foss import DocumentReader, LdmDocxWriter

reader = DocumentReader()
reader.load_file("input/report.docx")
ldm_doc = reader.to_light_document()

writer = LdmDocxWriter()
docx_bytes = writer.write_to_bytes(ldm_doc)
print(f"DOCX bytes: {len(docx_bytes)}")

# Save manually if desired
with open("output/report_copy.docx", "wb") as f:
    f.write(docx_bytes)

Round-Trip Pattern

The most common use case is a read-modify-write round trip:

from aspose.words_foss import DocumentReader, LdmDocxWriter

reader = DocumentReader()
reader.load_file("input/template.docx")
ldm_doc = reader.to_light_document()

# Inspect or modify the LDM here
print("Sections:", len(ldm_doc.sections))
print("Paragraphs:", len(ldm_doc.all_paragraphs))

writer = LdmDocxWriter()
writer.write(ldm_doc, "output/modified.docx")

Lossy-Write Warnings

When LdmDocxWriter cannot faithfully represent an LDM construct in DOCX format it emits a DocxWriterLossyWarning. You can capture these with Python’s warnings module to audit what was dropped:

import warnings
from aspose.words_foss import DocumentReader, LdmDocxWriter, DocxWriterLossyWarning

reader = DocumentReader()
reader.load_file("input/complex.docx")
ldm_doc = reader.to_light_document()

writer = LdmDocxWriter()
with warnings.catch_warnings(record=True) as w:
    warnings.simplefilter("always", DocxWriterLossyWarning)
    writer.write(ldm_doc, "output/complex_out.docx")

for warning in w:
    print("Lossy:", warning.message)

Tips and Best Practices

Always call DocumentReader.to_light_document() before passing the document to LdmDocxWriter — the writer expects an LDM Document, not a raw DocumentReader.
Use write_to_bytes() in web handlers to avoid temporary file management.
Check DocxWriterLossyWarning in tests to detect round-trip regressions when upgrading the library.
LdmDocxWriter.options is available for writer-level configuration; inspect the object after instantiation to see available settings.

Common Issues

Issue	Cause	Fix
`FileNotFoundError` on `write()`	Parent directory does not exist	Create the output directory with `Path.mkdir(parents=True, exist_ok=True)` before calling `write()`
`DocxWriterLossyWarning` emitted	LDM construct not representable in DOCX	Review the warning message; accept the loss or adjust the LDM before writing
Empty output DOCX	LDM document has no sections or paragraphs	Verify `ldm_doc.sections` and `ldm_doc.all_paragraphs` are non-empty after load

FAQ

What is the LDM (`light_document_model`)?

The LDM is Aspose.Words FOSS’s abstracted, Python-native representation of a Word document. It decouples document logic from the DOCX binary format and makes it easier to inspect and manipulate document structure programmatically.

Can I write to PDF instead of DOCX?

Yes — use LdmPdfWriter.write(doc, output_path) from the same package for PDF output, or LdmMarkdownWriter.write(doc, output_path) for Markdown.

Does `write_to_bytes()` require an output path?

No. write_to_bytes(doc) takes only the LDM document and returns a bytes object with no filesystem interaction.

API Reference Summary

Class / Method	Description
`LdmDocxWriter`	Converts an LDM `Document` to a DOCX file
`LdmDocxWriter.write(doc, output_path)`	Writes DOCX to the specified file path
`LdmDocxWriter.write_to_bytes(doc)`	Returns the DOCX content as `bytes`
`LdmDocxWriter.options`	Writer configuration options
`DocxWriterLossyWarning`	Warning raised when an LDM construct is dropped during write
`DocumentReader`	Reads a DOCX file and builds the LDM representation
`DocumentReader.to_light_document()`	Returns the loaded document as an LDM `Document`

Writing DOCX Files with LdmDocxWriter