Agfdhyk

I've been working on a flask app, which i'd like to bundle into an exe with pyinstaller. After many hours of frustrating and research I think I've come across the answer but I'm not sure how to proceed

Background

the flask app is structured like this:

/flaskapp

- routes.py

- table_func.py

- froms.py

- /static

    - /css

        - index.css

- /templates

    page.html

page.html is using the jinja2 template engine with flask to display tables which are created and styled with pandas, it is also displaying forms that I'm using flask-WTF to create.

Its designed so that the HTML stays the same and the content changes based on the tables that are sent to the HTML using jinja2 templating like so:

<div class="block">

        <div class="table1">

            {{ title | safe }}

        </div>

        <div class = "table2">

            {{ table | safe }}

        </div>

    </div>



    <br><br>



    <div class="block">

        <div class="table1">

            {{ title | safe }}

        </div>

        <div class="table2">

            {{ heat | safe }}

        </div>

    </div>

The reason for the multiple divs being used is for layout purposes

Issue

after packaging up the flask app using pyinstall it will only return and display pages that do not use the jinja2 template system, any pages that do make use of jinja2 templates throw out a NotImplementedError: Can't perform this operation for unregistered loader type error

So after lots of research and testing I'm pretty sure it is to do with the jinja2 template engine in flask not being supported with pyinstaller, specifically because of jinja2's use of the PackageLoader api as seen here

https://github.com/pyinstaller/pyinstaller/issues/1898

pyinstaller issue 183 seems to suggest this isn't an issue, but it still is since it isn't working]

through further digging through stack overflow and the jinja2 docs it seems like the best solution is to use jinja2's FileSystemLoader API instead of PackageLoader.

https://stackoverflow.com/questions/38642557/how-to-load-jinja-template-directly-from-filesystem



https://stackoverflow.com/questions/38617900/need-to-package-jinja2-template-for-python



http://jinja.pocoo.org/docs/2.10/api/#loaders

I'm assuming that once i convert to this it'll allow pyinstaller to package up the flask app and will stop throwing errors when trying to load a page using jinja2 templates.

But I'm not really sure how to proceed from this point, how do I tell flask to use a different loader within jinja2 when calling render_template()

I'm assuming flask has some way of configuring jinja2?