Tech Blog

Here I'll be sharing insights from my professional experiences and studies in data science and web development. There'll be plenty of Wagtail, Django and Python, a bit of JavaScript and CSS thrown in, and more on data science & engineering. There might even be a bit of time for some project management and business analysis too.

I'll also provide insights into how this site was made, as well as code examples and thoughts on how those could be further developed.

Feel free to leave questions or comments at the bottom of each post - I just ask people to create an account to filter out the spammers. You won't receive any unsolicited communication or find your email sold to a marketing list.

 

Showing blogs tagged with #wagtail

Create Thumbnails with Preserved Edges Using Python Image Library

Create Thumbnails with Preserved Edges Using Python Image Library

The Python Image Library (Pillow or PIL) has a host of image processing methods available to create images on-the-fly.

If you ever had the annoyance of uploading an image to a website, only to have it cropped to fit a certain aspect ratio, then this article is for you. I walk through creating thumbnails where the entire image is displayed without cropping or stretching while meeting the thumbnail dimension requirements

I'll also go through how to add this as an image filter in Wagtail so you can create thumbnail renders for your metadata.
Wagtail: Extending the Draftail Editor Part 3 - Dynamic Text

Wagtail: Extending the Draftail Editor Part 3 - Dynamic Text

In this third part of extending the Draftail editor, I introduce a way to add dynamic inline text to your rich text blocks using a combination of dummy inline element tags and JavaScript rather than the overly complicated entity route.

I'll go through an example of adding inline Font Awesome icons as a proof of concept which could be easily adapted to show any dynamic information such as stock indices, exchange rates, availability of a resource etc..
Wagtail: Extending the Draftail Editor Part 2 - Block Styles

Wagtail: Extending the Draftail Editor Part 2 - Block Styles

The second part of this series looks at customising and adding block styles to the Draftail rich text editor.

We walk through customising the blockquote style, add text alignment buttons to the editor as an example and then consider a different way to accomplish this outside of the editor with a StructBlock and why that might be preferable.
Wagtail: Extending the Draftail Editor Part 1 - Inline Styles

Wagtail: Extending the Draftail Editor Part 1 - Inline Styles

This article discusses how to create custom inline font styles not included by default in the Draftail rich text editor.

I'll include adding tag-based styling (such as <u>), how to add styled <span> tags and also demonstrate using both unicode glyphs and svg paths for your toolbar icon.
Configuring Rich Text Blocks for Your Wagtail Site

Configuring Rich Text Blocks for Your Wagtail Site

Rich text blocks are the most fundamental building block in any Wagtail site. You can make your code a lot tidier by defining the feature set as editors, extending the WSIWYG editor with additional features and finally adding the ability to define alignment on the fly.
Add Heading Blocks with Bookmarks in Wagtail

Add Heading Blocks with Bookmarks in Wagtail

Wagtail’s Draftail rich text editor lacks any way to add bookmarks to heading tags so that you can link back to that position on the page from elsewhere.

In this example, I create a simple StreamBlock to add to your Streamfields that includes heading size, alignment and an optional bookmark. I use ChoiceBlocks for the field values, a custom template with some basic logic and also include some validation to ensure the entered bookmark is a valid slug.

This is a good example to work through if you're starting out with Wagtail and getting used to working with blocks and StreamFields.
Adding MapBox Blocks to Wagtail Stream Fields

Adding MapBox Blocks to Wagtail Stream Fields

MapBox is an extremely versatile GIS tool that can be used not only for mapping and route planning, but also for presenting and analysing many types of GIS data. Setting up Wagtail map blocks using MapBox presents a few challenges.

I'll go over how to set up nested streams, how to overcome the problem of unique element IDs in recurring HTML blocks, and how to pass data structures from Django's backend to JavaScript functions.
Passing Data from Django & Wagtail to JavaScript the Safe Way

Passing Data from Django & Wagtail to JavaScript the Safe Way

Passing data from Django/Wagtail to JavaScript code is a common necessity, but often done in a way that will leave your site open to HTML injection and XSS attacks (cross-site scripting).

A quick flick through blog posts, editorials and forums (including the ubiquitous Stack Overflow) will yield a raft of dodgy solutions including rendering inline JavaScript directly into the template.

Surprisingly, the safe way to do this requires far less coding and allows you to pass complex data structures without the faff and without exposing your site to unnecessary risk.
Upgrading to Wagtail 3.0

Upgrading to Wagtail 3.0

Wagtail 3.0 is out with a lot of significant changes in architecture requiring code updates. The biggest work I found was the change in the way custom edit panels are handled in the admin interface which isn't well documented yet. Here are some examples I worked through to get up and running.
Use JavaScript to Add a Dynamic Table of Contents to Your Pages

Use JavaScript to Add a Dynamic Table of Contents to Your Pages

Creating a table of contents or menu based on content is time-consuming for editors and prone to errors. You may need such a feature on your data fed pages and not even have the ability to create and link to content on the page.

Here, I create an automated, on-the-fly table of contents without the need for hard-coded anchor links, regardless of the source of your content. It's easily adaptable to turn into a nav bar or similar menu. Similarly, this technique could be used to produce a summary with links on an API data feed page for rapid data analysis and drill-down capability.

At the end, I wrap it in a Wagtail stream block ready to drop into your templates.
Translating Static Template Text with Wagtail Localize

Translating Static Template Text with Wagtail Localize

You have all your page content and snippet components translating successfully, but what to do with all those bits of static text in the non-Wagtail pages?

Static text lurks in the error pages, search results, e-mail templates and any Django pages that may be getting served on your site.

Here's an easy way to keep it all under the Wagtail Localize umbrella without the pain of making PO files and peppering your templates with blocktrans tags.
Dealing with UNIQUE Fields on a Multi-lingual Site

Dealing with UNIQUE Fields on a Multi-lingual Site

In Django and Wagtail, for many translation models, a copy of the page tree is made for each language rather than inserting the translated text directly into the template or model.

This poses a problem for models that have fields with UNIQUE constraints as attempting to save a copy of the default language instance will trigger an integrity error (ie duplicate key).

Fortunately, if you're using the TranslatableMixin, there's a way around this.