If you’ve used Blazor for a while you may have run into the following (pretty unhelpful) error message where the page router is throwing a NullReferenceException:
The worst part is that I always seem to run into this error after making a bunch of changes and then having no idea exactly what I did to break the build (yeah I know, I should probably run my code more while making changes).
I’ve managed to form a general idea of why the error is thrown and have found two concrete situations that reproducibly cause the issue, so I’ve finally written them down for when I inevitably run into this situation again!
There’s a lot of flexibility in how you can use authorisation rules in Razor components*, but a frustration of this approach is that it seems like you have to slap @attribute [Authorize(Policy = "PolicyName")] at the top or every page with no clear way of applying a given policy to a whole folder of .razor files. After much research and testing, I’ve found how to go about it!
I’ve noticed an issue recently after upgrading a few Blazor projects from .NET 5 to .NET 6 where the UI flashes after every call to StateHasChanged. Something like this:
Yeah, that’s not annoying at all. Unfortunately it was happening in quite a few different places and was pretty darn noticeable, so it looked like I was going to have to dive in and figure out what exactly was causing this to go wrong (despite working perfectly in .NET 5)!
Blazorise is an excellent library that I’ve been using a lot lately. While it has great support for declaring custom visual themes, you’ll occasionally run into situations where what you’re trying to do isn’t fully supported.
Take this super contrived example: I want to set the shadow on a div to use the primary colour defined in my theme, but there’s no attribute in Blazorise to do this directly (at time of writing). I could hard-code the colour to the same hex value as what I’ve set in my theme, but not only is this generally bad practice (since it’s easy to update one value and not the other), it locks you into only one colour even though the theme can be modified dynamically during runtime. So how can we access our Blazorise theme values in custom CSS?
I’m sure I’m not the only one that has “temporarily” stored passwords, application keys or other development secrets in appsettings.json simply because it was easier or faster than doing it the right way (although if I am, this first sentence will surely come back to haunt me).
I get it. It happens! This blog post actually comes from my efforts to update a project I’m working on with some friends so that we’ve got a more consistent approach to keeping secrets… secret.
So how are we going to go about this? We’ll be using Secret Manager, a fantastically helpful tool built into the configuration API in ASP.NET Core that will let us keep the secrets out of appsettings while not require a change to how we access the settings in code. Sound good?
EVieBikes recently landed in Guernsey, bringing the first ever dockless shared electric vehicles to the island. I got into contact with Gavin Breeze (founder and CEO of EVie), who kindly agreed to discuss with me where EVie came from, what the service means for the islands and their plans for the future!
Interview conducted on 2021/04/09.
A Brief History of EVie
According to Gavin, EVie bikes were “sort of all [his] fault”. After founding a software as a service (SaaS) payment company called DataCash and selling it to MasterCard, he found himself at a loose end. Deciding that he was “too young to sit around doing nothing” Gavin looked for his next project, which came shortly after hearing Phil Male (Chairman of JT) discuss a number of ideas he had for improving Jersey. Of the ideas put forth, Gavin decided that “as a private individual the only one [he] could have the […] remotest impact on was to try and move the dial towards the islands becoming all-electric islands” (moving away from internal combustion engine vehicles).
I’ve been writing regular expressions (regex) for years and would consider myself pretty good at them by now (I decline to provide references). The problem is that although it’s common to see regex as cryptic and painfully terse (which are not invalid points), they remain one of the best ways to handle complex pattern matching and as such you’ll probably run into them at least a few times in your career.
Even if you really despise writing regular expressions, here are some tips that will help to make that process as painless as possible!
If you want to just get to the good stuff, scroll down to the “Setup” section.
My wife and I finally got a new printer to replace the old one that has pretty much given up the ghost and refuses to print anymore (often considered an important feature for devices like this).
We settled on an Epson ET-2711 in large part because of the ink tank that should (hopefully) do away with the constant stream of expensive cartridges in favour of some cheaper-per-page ink bottles. I was excited to get it out and start setting it up (in part because we’re in another lockdown and what else is there to do right now)!
Imagine my frustration, dear reader, when I found out that the whole wireless setup process for this printer is terrible if you follow the official instructions. I genuinely spent a couple of hours bouncing between the Android app (which gave me a very helpful message telling me “Communication error”, to check the printer is on and not much else), the included software for Windows (which was just as helpful), the printed documentation in the box and the website, all to no avail.
The good news is that I finally figured out how to get it working. The even better news for you at home is that I’ve gone through the process three times so that I could document all of the steps to get this working properly!