docx4j for Python

docx4j for Python: the whole of ECMA-376 WordprocessingML as typed objects, generated from docx4j's own schema tree; docx4j's Open Packaging engine written by hand over them (.docx in, typed parts and relationships, .docx out, every part you did not touch written back byte for byte); a content API in the vocabulary of Office JS's Word.Body, Paragraph, Range, Table, comments, tracked changes and lists, built for agents; and a python-docx facade so code already written runs. The classes carry docx4j's names (P, R, PPr, Tbl, Document, Styles), so fifteen years of docx4j documentation and examples read across; the design is the same as docx4j-core-ts.

pip install docx4j

The distribution is docx4j; the import name is docx4j_py, as python-docx imports as docx. Python 3.12 or later.

Open, edit, save

from docx4j_py import load

pkg = load("in.docx")                                # a WordprocessingMLPackage
body = pkg.body                                      # Word.Body over word/document.xml

print(body.text)                                     # a paragraph per line
for paragraph in body.paragraphs:                    # tables and content controls descended into
    print(paragraph.style, paragraph.text)

title = body.insert_paragraph("Report", location="Start", style="Heading 1")
title.alignment = "Centered"
hit = body.search("quick brown fox")[0]              # matches span runs freely
hit.font.italic = True                               # the runs are split at the boundaries
hit.insert_text("slow red fox")                      # Replace is a Range's default location
body.paragraphs[-1].insert_paragraph("The end.")     # After is a Paragraph's

pkg.save("out.docx")                                 # only the parts you touched are re-marshalled

A part that is never touched is written back byte for byte; reading a part's contents --- which pkg.body does for word/document.xml --- marks it for re-marshalling, and a re-marshalled part is canonically identical to its source. Nothing is dropped silently: what lenient parsing could not place is reported per part (part.skipped), and LoadOptions(strict=True) raises instead.

From nothing:

from docx4j_py import create_package

pkg = create_package()                       # docx4j's createPackage: A4, one section, the default styles
body = pkg.body
body.insert_paragraph("Created by docx4j", style="Heading 1")
paragraph = body.insert_paragraph("One paragraph, three runs")
paragraph.search("three runs")[0].font.italic = True
table = body.insert_table(3, 2, values=[["Name", "Value"], ["a", "1"]], style="TableGrid")
table.header_row_count = 1
table.add_rows(1, values=[["b", "2"]])
pkg.save("hello.docx")

For agents

An agent cannot hold a Python object across tool calls, and a 200-page document does not fit in its context window. So the API gives it addresses --- strings that survive an edit --- and budgets on everything it reads. Four calls are the loop: read the outline, find the text, edit by address, check the report.

from docx4j_py import load

pkg = load("in.docx")

outline = pkg.outline()                       # small, structured, enough to choose an address from
outline.to_markdown()                         # the cheapest thing to show a model
outline.to_json()                             # under 64 KB for a 200-page document

hits = pkg.find("quick brown fox")            # matches with their addresses and 40 characters either side
hits[0].address, hits[0].snippet              # ('w14:5A2B1C3D', '… over the quick brown fox, which …')

paragraph = pkg.paragraph_at(hits[0].address) # 'w14:5A2B1C3D', 'body/3', or contains='Chapter 1'
paragraph.insert_paragraph("Added by an agent.", location="After")

pkg.last_change.to_json()                     # what that call did, for the tool result
pkg.save("out.docx")

w14:5A2B1C3D is the w14:paraId Word writes and survives every edit; body/3 is the ordinal. Every mutating call records a ChangeReport; pkg.dry_run() applies calls to a copy and throws it away; describe() reads what the document offers (its styles, page, parts, authors) without unmarshalling anything; every error carries a code and a hint naming what to do instead.

An agent should leave the trail Word already has: tracked changes for what it did, and a comment for why, where the human who opens the document will see them.

from docx4j_py import load
from docx4j_py.model.content import Author

pkg = load("in.docx")
pkg.author = Author("Claude", initials="C", email="claude@example.com")
pkg.change_tracking_mode = "TrackAll"          # every edit from here is a revision

count = pkg.body.replace_text("document", "report")     # a w:del and a w:ins per hit
pkg.find("report")[0].range(pkg.body).insert_comment(
    "Changed 'document' to 'report': the brief asks for a report."
)
[c.to_dict() for c in pkg.get_tracked_changes()]        # for the tool result
pkg.body.to_markdown(view="markup")                     # {--deleted--}{++inserted++}{>>a comment<<}
pkg.save("out.docx")

Markdown goes both ways: pkg.to_markdown(addresses=True) puts each block's address in an HTML comment before it, and body.insert_markdown(text) writes CommonMark plus GFM tables through the document's own styles, creating the numbering part when there is none.

python-docx code runs

docx4j_py.docx is a structural subset of python-docx's public API --- python-docx's names and semantics, this engine underneath. Its promise is a committed member list derived from python-docx 1.2.0: 305 of 312 members, the rest refused with a reason each. python-docx is not a dependency.

from docx4j_py.docx import Document, Pt

doc = Document("in.docx")                             # or Document() for a new one
doc.add_heading("Report", level=1)                    # a built-in style it lacks is defined
p = doc.add_paragraph("Plain, ")
p.add_run("bold").bold = True
p.runs[1].font.size = Pt(14)
doc.add_table(rows=2, cols=2, style="Table Grid").cell(0, 0).text = "a"
for paragraph in doc.paragraphs:
    print(paragraph.style.name, paragraph.text)

print(doc.package.last_change.to_dict())              # what python-docx does not have: a ChangeReport,
doc.save("out.docx")                                  # parts untouched byte for byte, the typed tree

The object model and the engine

Every element has a constructor in its namespace's el module, with p, r, t and tbl as sugar; wml(...) parses a fragment with docx4j's prefixes declared; to_xml is the inverse. The tree stays reachable from every view (paragraph.element is the typed P).

from docx4j_py.wml import el, p, r, to_xml, wml

para = p("Hello ", r("World", bold=True), style="Heading1")
same = wml('<w:p><w:pPr><w:pStyle w:val="Heading1"/></w:pPr><w:r><w:t>Hello</w:t></w:r></w:p>')
print(to_xml(el.p(content=[el.r(content=[el.t("Hello World")])]), pretty=True))

Under docx4j_py.openpackaging: OpcPackage, WordprocessingMLPackage, PartName, ContentTypeManager, RelationshipsPart, the typed WordprocessingML parts, PartStore and PartSink (zip, directory, memory, flat OPC); docx4j_py.model has docx4j's PropertyResolver, StyleUtil, numbering emulator and font selection, with zero differences on docx4j's 45 parity goldens.

from docx4j_py import load
from docx4j_py.openpackaging import LoadOptions, MemoryPartSink
from docx4j_py.wml import warm_up

warm_up()                                             # a server does this once, before the first request
with load("in.docx", options=LoadOptions(strict=True)) as pkg:
    settings = pkg.get_part("/word/settings.xml").contents   # typed, lazily, on first access
    pkg.save_to(MemoryPartSink())

What is and is not in 0.1

WordprocessingML only. .pptx and .xlsx load and save through the generic OPC path (every part byte for byte), but nothing in them is typed: PresentationML and SpreadsheetML are CR-001 Phase D (the object model) and CR-002 Phase C (the engine), and their content APIs are CR-004 and CR-005. Everything is synchronous.

The wheel is large for pure Python --- about 1 MB compressed, 238 modules, 6 MB installed --- because it is the whole of WordprocessingML and what it embeds (DrawingML, OMML, VML, the w14 to w16 extensions) as typed classes, 148,000 lines of generated code. Importing docx4j_py imports all of it, about 0.6 s once per process; a long-running process is the intended host.

What 0.x promises, surface by surface:

Links

• Repository: https://github.com/plutext/docx4j-python --- the full README, with the whole content API, the audit trail, lists, custom XML templates and to_api_script shown
• The design, as change requests: CR-001 the object model, CR-002 the engine, CR-003 the content API
• docx4j, the Java original, and docx4j-core-ts, the TypeScript engine of the same design
• Changelog

Apache-2.0, as docx4j is; the generated model imports docx4j-xsdata, a fork of xsdata (MIT). Every fence above is executed by the test suite (tests/test_readme.py).