Text extraction for Wagtail document search

This package is for replacing Wagtail's Document class with one that allows searching in Document file contents using textract.

Textract can extract text from (among others) PDF, Excel and Word files.

The package was inspired by the "Search: Extract text from documents" issue in Wagtail.

Documents will work as before, except that Document search in Wagtail's admin interface will also find search terms in the files' contents.

Some screenshots to illustrate.

In our fresh Wagtail site with wagtail_textract installed, we uploaded a file called test_document.pdf with handwritten text in it. It is listed in the admin interface under Documents:

If we now search in Documents for the word correct, which is one of the handwritten words, the live search finds it:

The assumption is that this search should not only be available in Wagtail's admin interface, but also in a public-facing search view, for which we provide a code example.

Requirements

• Wagtail 2 (see tox.ini)
• The Textract dependencies

Maturity

We have been using this package in production since August 2018 on https://nuffic.nl.

Installation

• Install the Textract dependencies
• Add wagtail_textract to your requirements and/or pip install wagtail_textract
• Add to your Django INSTALLED_APPS.
• Put WAGTAILDOCS_DOCUMENT_MODEL = "wagtail_textract.document" in your Django settings.

Note: You'll get an incompatibility warning during installation of wagtail_textract (Wagtail 2.0.1 installed):

requests 2.18.4 has requirement chardet<3.1.0,>=3.0.2, but you'll have chardet 2.3.0 which is incompatible.
textract 1.6.1 has requirement beautifulsoup4==4.5.3, but you'll have beautifulsoup4 4.6.0 which is incompatible.

We haven't seen this leading to problems, but it's something to keep in mind.

Tesseract

In order to make textract use Tesseract, which happens if regular textract finds no text, you need to add the data files that Tesseract can base its word matching on.

Create a tessdata directory in your project directory, and download the languages you want.

Transcribing

Transcription is done automatically after Document save, in an asyncio executor to prevent blocking the response during processing.

To transcribe all existing Documents, run the management command::

./manage.py transcribe_documents

This may take a long time, obviously.

Usage in custom view

Here is a code example for a search view (outside Wagtail's admin interface) that shows both Page and Document results.

from itertools import chain

from wagtail.core.models import Page
from wagtail.documents.models import get_document_model


def search(request):
    # Search
    search_query = request.GET.get('query', None)
    if search_query:
        page_results = Page.objects.live().search(search_query)
        document_results = Document.objects.search(search_query)
        search_results = list(chain(page_results, document_results))

        # Log the query so Wagtail can suggest promoted results
        Query.get(search_query).add_hit()
    else:
        search_results = Page.objects.none()

    # Render template
    return render(request, 'website/search_results.html', {
        'search_query': search_query,
        'search_results': search_results,
    })

Your template should allow for handling Documents differently than Pages, because you can't do pageurl result on a Document:

{% if result.file %}
   <a href="{{ result.url }}">{{ result }}</a>
{% else %}
   <a href="{% pageurl result %}">{{ result }}</a>
{% endif %}

What if you already use a custom Document model?

In order to use wagtail_textract, your CustomizedDocument model should do the same as wagtail_textract's Document:

• subclass TranscriptionMixin
• alter search_fields

from wagtail_textract.models import TranscriptionMixin


class CustomizedDocument(TranscriptionMixin, ...):
    """Extra fields and methods for Document model."""
    search_fields = ... + [
        index.SearchField(
            'transcription',
            partial_match=False,
        ),
    ]

Note that the first class to subclass should be TranscriptionMixin, so its save() takes precedence over that of the other parent classes.

Tests

To run tests, checkout this repository and:

make test

Coverage

A coverage report will be generated in ./coverage_html_report/.

Contributors

• Karl Hobley
• Bertrand Bordage
• Kees Hink
• Tom Hendrikx
• Coen van der Kamp
• Mike Overkamp
• Thibaud Colas
• Dan Braghis
• Dan Swain