Mammoth .docx to HTML converter

Mammoth is designed to convert .docx documents, such as those created by Microsoft Word, and convert them to HTML. Mammoth aims to produce simple and clean HTML by using semantic information in the document, and ignoring other details. For instance, Mammoth converts any paragraph with the style Heading 1 to h1 elements, rather than attempting to exactly copy the styling (font, text size, colour, etc.) of the heading.

There's a large mismatch between the structure used by .docx and the structure of HTML, meaning that the conversion is unlikely to be perfect for more complicated documents. Mammoth works best if you only use styles to semantically mark up your document.

The following features are currently supported:

• Headings.

• Lists.

• Customisable mapping from your own docx styles to HTML. For instance, you could convert WarningHeading to h1.warning by providing an appropriate style mapping.

• Tables. The formatting of the table itself, such as borders, is currently ignored, but the formatting of the text is treated the same as in the rest of the document.

• Footnotes and endnotes.

• Images.

• Bold, italics, underlines, strikethrough, superscript and subscript.

• Links.

• Line breaks.

• Text boxes. The contents of the text box are treated as a separate paragraph that appears after the paragraph containing the text box.

• Comments.

Installation

pip install mammoth

Other supported platforms

• JavaScript, both the browser and node.js. Available on npm.

• WordPress.

• Java/JVM. Available on Maven Central.

• .NET. Available on NuGet.

Usage

CLI

You can convert docx files by passing the path to the docx file and the output file. For instance:

mammoth document.docx output.html

If no output file is specified, output is written to stdout instead.

The output is an HTML fragment, rather than a full HTML document, encoded with UTF-8. Since the encoding is not explicitly set in the fragment, opening the output file in a web browser may cause Unicode characters to be rendered incorrectly if the browser doesn't default to UTF-8.

Images

By default, images are included inline in the output HTML. If an output directory is specified by --output-dir, the images are written to separate files instead. For instance:

mammoth document.docx --output-dir=output-dir

Existing files will be overwritten if present.

Styles

A custom style map can be read from a file using --style-map. For instance:

mammoth document.docx output.html --style-map=custom-style-map

Where custom-style-map looks something like:

p[style-name='Aside Heading'] => div.aside > h2:fresh
p[style-name='Aside Text'] => div.aside > p:fresh

Markdown

Using --output-format=markdown will cause Markdown to be generated. For instance:

mammoth document.docx --output-format=markdown

Markdown support is still in its early stages, so you may find some features are unsupported.

Library

Basic conversion

To convert an existing .docx file to HTML, pass a file-like object to mammoth.convert_to_html. The file should be opened in binary mode. For instance:

import mammoth

with open("document.docx", "rb") as docx_file:
    result = mammoth.convert_to_html(docx_file)
    html = result.value # The generated HTML
    messages = result.messages # Any messages, such as warnings during conversion

You can also extract the raw text of the document by using mammoth.extract_raw_text. This will ignore all formatting in the document. Each paragraph is followed by two newlines.

with open("document.docx", "rb") as docx_file:
    result = mammoth.extract_raw_text(docx_file)
    text = result.value # The raw text
    messages = result.messages # Any messages

Custom style map

By default, Mammoth maps some common .docx styles to HTML elements. For instance, a paragraph with the style name Heading 1 is converted to a h1 element. You can pass in a custom map for styles by passing an options object with a style_map property as a second argument to convert_to_html. A description of the syntax for style maps can be found in the section "Writing style maps". For instance, if paragraphs with the style name Section Title should be converted to h1 elements, and paragraphs with the style name Subsection Title should be converted to h2 elements:

import mammoth

style_map = """
p[style-name='Section Title'] => h1:fresh
p[style-name='Subsection Title'] => h2:fresh
"""

with open("document.docx", "rb") as docx_file:
    result = mammoth.convert_to_html(docx_file, style_map=style_map)

User-defined style mappings are used in preference to the default style mappings. To stop using the default style mappings altogether, pass include_default_style_map=False:

result = mammoth.convert_to_html(docx_file, style_map=style_map, include_default_style_map=False)

Custom image handlers

By default, images are converted to <img> elements with the source included inline in the src attribute. This behaviour can be changed by setting the convert_image argument to an image converter .

For instance, the following would replicate the default behaviour:

def convert_image(image):
    with image.open() as image_bytes:
        encoded_src = base64.b64encode(image_bytes.read()).decode("ascii")
    
    return {
        "src": "data:{0};base64,{1}".format(image.content_type, encoded_src)
    }

mammoth.convert_to_html(docx_file, convert_image=mammoth.images.img_element(convert_image))

Bold

By default, bold text is wrapped in <strong> tags. This behaviour can be changed by adding a style mapping for b. For instance, to wrap bold text in <em> tags:

style_map = "b => em"

with open("document.docx", "rb") as docx_file:
    result = mammoth.convert_to_html(docx_file, style_map=style_map)

Italic

By default, italic text is wrapped in <em> tags. This behaviour can be changed by adding a style mapping for i. For instance, to wrap italic text in <strong> tags:

style_map = "i => strong"

with open("document.docx", "rb") as docx_file:
    result = mammoth.convert_to_html(docx_file, style_map=style_map)

Underline

By default, the underlining of any text is ignored since underlining can be confused with links in HTML documents. This behaviour can be changed by adding a style mapping for u. For instance, suppose that a source document uses underlining for emphasis. The following will wrap any explicitly underlined source text in <em> tags:

import mammoth

style_map = "u => em"

with open("document.docx", "rb") as docx_file:
    result = mammoth.convert_to_html(docx_file, style_map=style_map)

Strikethrough

By default, strikethrough text is wrapped in <s> tags. This behaviour can be changed by adding a style mapping for strike. For instance, to wrap strikethrough text in <del> tags:

style_map = "strike => del"

with open("document.docx", "rb") as docx_file:
    result = mammoth.convert_to_html(docx_file, style_map=style_map)

Comments

By default, comments are ignored. To include comments in the generated HTML, add a style mapping for comment-reference. For instance:

style_map = "comment-reference => sup"

with open("document.docx", "rb") as docx_file:
    result = mammoth.convert_to_html(docx_file, style_map=style_map)

Comments will be appended to the end of the document, with links to the comments wrapped using the specified style mapping.

API

mammoth.convert_to_html(fileobj, **kwargs)

Converts the source document to HTML.

• fileobj: a file-like object containing the source document. Files should be opened in binary mode.

• style_map: a string to specify the mapping of Word styles to HTML. See the section "Writing style maps" for a description of the syntax.

• include_embedded_style_map: by default, if the document contains an embedded style map, then it is combined with the default style map. To ignore any embedded style maps, pass include_embedded_style_map=False.

• include_default_style_map: by default, the style map passed in style_map is combined with the default style map. To stop using the default style map altogether, pass include_default_style_map=False.

• convert_image: by default, images are converted to <img> elements with the source included inline in the src attribute. Set this argument to an image converter to override the default behaviour.

• ignore_empty_paragraphs: by default, empty paragraphs are ignored. Set this option to False to preserve empty paragraphs in the output.

• id_prefix: a string to prepend to any generated IDs, such as those used by bookmarks, footnotes and endnotes. Defaults to an empty string.

• transform_document: if set, this function is applied to the document read from the docx file before the conversion to HTML. The API for document transforms should be considered unstable. See document transforms.

• Returns a result with the following properties:

  • value: the generated HTML

  • messages: any messages, such as errors and warnings, generated during the conversion

mammoth.convert_to_markdown(fileobj, **kwargs)

Converts the source document to Markdown. This behaves the same as convert_to_html, except that the value property of the result contains Markdown rather than HTML.

mammoth.extract_raw_text(fileobj)

Extract the raw text of the document. This will ignore all formatting in the document. Each paragraph is followed by two newlines.

• fileobj: a file-like object containing the source document. Files should be opened in binary mode.

• Returns a result with the following properties:

  • value: the raw text

  • messages: any messages, such as errors and warnings

mammoth.embed_style_map(fileobj, style_map)

Embeds the style map style_map into fileobj. When Mammoth reads a file object, it will use the embedded style map.

• fileobj: a file-like object containing the source document. Files should be opened for reading and writing in binary mode.

• style_map: the style map to embed.

• Returns None.

Messages

Each message has the following properties:

• type: a string representing the type of the message, such as "warning"

• message: a string containing the actual message

Image converters

An image converter can be created by calling mammoth.images.img_element(func). This creates an <img> element for each image in the original docx. func should be a function that has one argument image. This argument is the image element being converted, and has the following properties:

• open(): open the image file. Returns a file-like object.

• content_type: the content type of the image, such as image/png.

func should return a dict of attributes for the <img> element. At a minimum, this should include the src attribute. If any alt text is found for the image, this will be automatically added to the element's attributes.

For instance, the following replicates the default image conversion:

def convert_image(image):
    with image.open() as image_bytes:
        encoded_src = base64.b64encode(image_bytes.read()).decode("ascii")
    
    return {
        "src": "data:{0};base64,{1}".format(image.content_type, encoded_src)
    }

mammoth.images.img_element(convert_image)

mammoth.images.data_uri is the default image converter.

WMF images are not handled by default by Mammoth. The recipes directory contains an example of how they can be converted using LibreOffice, although the fidelity of the conversion depends entirely on LibreOffice.

Document transforms

The API for document transforms should be considered unstable, and may change between any versions. If you rely on this behaviour, you should pin to a specific version of Mammoth, and test carefully before updating.

Mammoth allows a document to be transformed before it is converted. For instance, suppose that document has not been semantically marked up, but you know that any centre-aligned paragraph should be a heading. You can use the transform_document argument to modify the document appropriately:

import mammoth.transforms

def transform_paragraph(element):
    if element.alignment == "center" and not element.style_id:
        return element.copy(style_id="Heading2")
    else:
        return element

transform_document = mammoth.transforms.paragraph(transform_paragraph)

mammoth.convert_to_html(fileobj, transform_document=transform_document)

Or if you want paragraphs that have been explicitly set to use monospace fonts to represent code:

import mammoth.documents
import mammoth.transforms

_monospace_fonts = set(["courier new"])

def transform_paragraph(paragraph):
    runs = mammoth.transforms.get_descendants_of_type(paragraph, mammoth.documents.Run)
    if runs and all(run.font and run.font.lower() in _monospace_fonts for run in runs):
        return paragraph.copy(style_id="code", style_name="Code")
    else:
        return paragraph

convert_to_html(
    fileobj,
    transform_document=mammoth.transforms.paragraph(transform_paragraph),
    style_map="p[style-name='Code'] => pre:separator('\n')",
)

mammoth.transforms.paragraph(transform_paragraph)

Returns a function that can be used as the transform_document argument. This will apply the function transform_paragraph to each paragraph element. transform_paragraph should return the new paragraph.

mammoth.transforms.run(transform_run)

Returns a function that can be used as the transform_document argument. This will apply the function transform_run to each run element. transform_run should return the new run.

mammoth.transforms.get_descendants(element)

Gets all descendants of an element.

mammoth.transforms.get_descendants_of_type(element, type)

Gets all descendants of a particular type of an element. For instance, to get all runs within an element paragraph:

import mammoth.documents
import mammoth.transforms

runs = mammoth.transforms.get_descendants_of_type(paragraph, documents.Run);

Writing style maps

A style map is made up of a number of style mappings separated by new lines. Blank lines and lines starting with # are ignored.

A style mapping has two parts:

• On the left, before the arrow, is the document element matcher.
• On the right, after the arrow, is the HTML path.

When converting each paragraph, Mammoth finds the first style mapping where the document element matcher matches the current paragraph. Mammoth then ensures the HTML path is satisfied.

Freshness

When writing style mappings, it's helpful to understand Mammoth's notion of freshness. When generating, Mammoth will only close an HTML element when necessary. Otherwise, elements are reused.

For instance, suppose one of the specified style mappings is p[style-name='Heading 1'] => h1. If Mammoth encounters a .docx paragraph with the style name Heading 1, the .docx paragraph is converted to a h1 element with the same text. If the next .docx paragraph also has the style name Heading 1, then the text of that paragraph will be appended to the existing h1 element, rather than creating a new h1 element.

In most cases, you'll probably want to generate a new h1 element instead. You can specify this by using the :fresh modifier:

p[style-name='Heading 1'] => h1:fresh

The two consective Heading 1 .docx paragraphs will then be converted to two separate h1 elements.

Reusing elements is useful in generating more complicated HTML structures. For instance, suppose your .docx contains asides. Each aside might have a heading and some body text, which should be contained within a single div.aside element. In this case, style mappings similar to p[style-name='Aside Heading'] => div.aside > h2:fresh and p[style-name='Aside Text'] => div.aside > p:fresh might be helpful.

Document element matchers

Paragraphs, runs and tables

Match any paragraph:

p

Match any run:

r

Match any table:

table

To match a paragraph, run or table with a specific style, you can reference the style by name. This is the style name that is displayed in Microsoft Word or LibreOffice. For instance, to match a paragraph with the style name Heading 1:

p[style-name='Heading 1']

You can also match a style name by prefix. For instance, to match a paragraph where the style name starts with Heading:

p[style-name^='Heading']

Styles can also be referenced by style ID. This is the ID used internally in the .docx file. To match a paragraph or run with a specific style ID, append a dot followed by the style ID. For instance, to match a paragraph with the style ID Heading1:

p.Heading1

Bold

Match explicitly bold text:

b

Note that this matches text that has had bold explicitly applied to it. It will not match any text that is bold because of its paragraph or run style.

Italic

Match explicitly italic text:

i

Note that this matches text that has had italic explicitly applied to it. It will not match any text that is italic because of its paragraph or run style.

Underline

Match explicitly underlined text:

u

Note that this matches text that has had underline explicitly applied to it. It will not match any text that is underlined because of its paragraph or run style.

Strikethough

Match explicitly struckthrough text:

strike

Note that this matches text that has had strikethrough explicitly applied to it. It will not match any text that is struckthrough because of its paragraph or run style.

Small caps

Match explicitly small caps text:

small-caps

Note that this matches text that has had small caps explicitly applied to it. It will not match any text that is small caps because of its paragraph or run style.

HTML paths

Single elements

The simplest HTML path is to specify a single element. For instance, to specify an h1 element:

h1

To give an element a CSS class, append a dot followed by the name of the class:

h1.section-title

To require that an element is fresh, use :fresh:

h1:fresh

Modifiers must be used in the correct order:

h1.section-title:fresh

Separators

To specify a separator to place between the contents of paragraphs that are collapsed together, use :separator('SEPARATOR STRING').

For instance, suppose a document contains a block of code where each line of code is a paragraph with the style Code Block. We can write a style mapping to map such paragraphs to <pre> elements:

p[style-name='Code Block'] => pre

Since pre isn't marked as :fresh, consecutive pre elements will be collapsed together. However, this results in the code all being on one line. We can use :separator to insert a newline between each line of code:

p[style-name='Code Block'] => pre:separator('\n')

Nested elements

Use > to specify nested elements. For instance, to specify h2 within div.aside:

div.aside > h2

You can nest elements to any depth.