python-docx insertion point

Question

I am not sure if I've been missing anything obvious, but I have not found anything documented about how one would go to insert Word elements (tables, for example) at some specific place in a document?

I am loading an existing MS Word .docx document by using:

my_document = Document('some/path/to/my/document.docx')

My use case would be to get the 'position' of a bookmark or section in the document and then proceed to insert tables below that point.

I'm thinking about an API that would allow me to do something along those lines:

insertion_point = my_document.bookmarks['bookmark_name'].position
my_document.add_table(rows=10, cols=3, position=insertion_point+1)

I saw that there are plans to implement something akin to the 'range' object of the MS Word API, this would effectively solve that problem. In the meantime, is there a way to instruct the document object methods where to insert the new elements?

Maybe I can glue some lxml code to find a node and pass that to these python-docx methods? Any help on this subject would be much appreciated! Thanks.

Answer 1

I remembered an old adage, "use the source, Luke!", and could figure it out. A post from python-docx owner on its git project page also gave me a hint: https://github.com/python-openxml/python-docx/issues/7.

The full XML document model can be accessed by using the its _document_part._element property. It behaves exactly like an lxml etree element. From there, everything is possible.

To solve my specific insertion point problem, I created a temp docx.Document object which I used to store my generated content.

import docx
from docx.oxml.shared import qn
tmp_doc = docx.Document()

# Generate content in tmp_doc document
tmp_doc.add_heading('New heading', 1)
# more content generation using docx API.
# ...

# Reference the tmp_doc XML content
tmp_doc_body = tmp_doc._document_part._element.body
# You could pretty print it by using:
#print(docx.oxml.xmlchemy.serialize_for_reading(tmp_doc_body))

I then loaded my docx template (containing a bookmark named 'insertion_point') into a second docx.Document object.

doc = docx.Document('/some/path/example.docx')
doc_body = doc._document_part._element.body
#print(docx.oxml.xmlchemy.serialize_for_reading(doc_body))

The next step is parsing the doc XML to find the index of the insertion point. I defined a small function for the task at hand, which returns a named bookmark parent paragraph element:

def get_bookmark_par_element(document, bookmark_name):
"""
Return the named bookmark parent paragraph element. If no matching
bookmark is found, the result is '1'. If an error is encountered, '2'
is returned.
"""
doc_element = document._document_part._element
bookmarks_list = doc_element.findall('.//' + qn('w:bookmarkStart'))
for bookmark in bookmarks_list:
    name = bookmark.get(qn('w:name'))
    if name == bookmark_name:
        par = bookmark.getparent()
        if not isinstance(par, docx.oxml.CT_P): 
            return 2
        else:
            return par
return 1

The newly defined function was used toget the bookmark 'insertion_point' parent paragraph. Error control is left to the reader.

bookmark_par = get_bookmark_par_element(doc, 'insertion_point')

We can now use bookmark_par's etree index to insert our tmp_doc generated content at the right place:

bookmark_par_parent = bookmark_par.getparent()
index = bookmark_par_parent.index(bookmark_par) + 1
for child in tmp_doc_body:
    bookmark_par_parent.insert(index, child)
    index = index + 1
bookmark_par_parent.remove(bookmark_par)

The document is now finalized, the generated content having been inserted at the bookmark location of an existing Word document.

# Save result
# print(docx.oxml.xmlchemy.serialize_for_reading(doc_body))
doc.save('/some/path/generated_doc.docx')

I hope this can help someone, as the documentation regarding this is still yet to be written.