Possibly-Useful on dev.endevour

Express router for better code organisation

Mon, 28 Apr 2025 00:00:00 +0000

A Node/Express app I’m working on has been sprouting routes so much that the server.js file has swollen to 800 lines - way past my 200-250 comfort zone, so it’s time to organise the routes into their own files. That seems like a good topic for a beginner blog post, so let’s dive in.

Imagine we’ve written this little Node/Express app.

import express from "express";
import {
 dbCustomersGet,
 dbCustomersGetById,
 dbCustomersDelete,
 dbOrdersGet,
 dbOrdersGetById,
 dbOrdersGetByCustomerId,
 dbOrdersDelete,
} from "./db.js";

const app = express();
app.set("view engine", "ejs");
const port = 3002;

app.use(express.urlencoded({ extended: true }));

app.get("/", (req, res) => {
 res.redirect("/customers");
});

app.get("/customers", (req, res) => {
 const customers = dbCustomersGet();
 res.render("customers", { customers });
});

app.get("/customers/:id", (req, res) => {
 const customer = dbCustomersGetById(req.params.id);
 const orders = dbOrdersGetByCustomerId(req.params.id);
 res.render("customer", { customer, orders });
});

app.get("/customers/:id/delete", (req, res) => {
 dbCustomersDelete(req.params.id);
 res.redirect("/customers");
});

app.get("/orders", (req, res) => {
 const orders = dbOrdersGet();
 res.render("orders", { orders });
});

app.get("/orders/:id", (req, res) => {
 const order = dbOrdersGetById(req.params.id);
 const customer = dbCustomersGetById(order.customerId);
 res.render("order", { order, customer });
});

app.get("/orders/:id/delete", (req, res) => {
 dbOrdersDelete(req.params.id);
 res.redirect("/orders");
});

app.listen(port, () => {
 console.log(`Listening on http://127.0.0.1:${port}`);
});

Although concocted, this would seem familiar to anyone who’s built a CRUD business app.

A bit of web-scraping with Cheerio

Mon, 17 Feb 2025 00:00:00 +0000

I had an idea for a little holiday project that required a list of episodes from The Rest Is History podcast. On their ‘Episodes’ page, they have a player, and a list of post entries for the most recent eighteen podcasts. There is a ‘show all’ button, but it doesn’t work.

The player does contain the full list of episodes (about 600) including a number of duplicates, so I expected if I inspected the network calls that I’d see a JSON package arriving with what I wanted. This is what I almost always find these days so I’ve had very little call to do any real web scraping - it’s normally just a matter of locating the endpoint and perhaps extracting an API key from a header.

Command chaining with NTFY for long running commands

Mon, 03 Feb 2025 00:00:00 +0000

NTFY is a great open-source push notification service that’s self-hostable or free to use (although I suggest you pay for it as I do). I’ve written before how I use it with UptimeKuma for my uptime monitoring, but another common use is just when I’m initiating long-running commands and backgrounding them.

This magic is possible since we can just curl to send a NTFY notification. For example:

curl -d "😀 demo push message via NTFY" ntfy.sh/blog_demo

Since I’m subscribed to the “blog_demo” topic in NTFY, this message will be pushed to my phone and watch:

Share files securely with Enclosed

Mon, 27 Jan 2025 00:00:00 +0000

My accountant works for one of those giant firms, and it bugs me that I’m emailing him password protected zip files of my accounts rather than to a secure upload facility at his firm. I can fix this with the power of self hosting, by running my own secure file dropping app on a VPS.

There’s a number of applications that do this sort of thing - allow you to upload a file, get a link in return which you can then share to people to download the file. For this to be more secure than emailing, the file needs to be encrypted on the server, and we want to be able to set a password, impose limits on downloads, and limit how long the link lives for. I’ve previously looked at Sharry which adds the ability for unauthenticated users to upload files to you securely, but for this slightly simpler job, I chose Enclosed by Corentin Thomasset .

Moving a Docker image as a file

Mon, 20 Jan 2025 00:00:00 +0000

I’m having a super annoying problem at the moment, I can’t pull down containers from DockerHub. If I hotspot my laptop off my phone it works fine, so it’s some drama with the home internet connection that rebooting the router does not fix.

I’ve had a couple of different errors including Error response from daemon: Get "https://registry-1.docker.io/v2/": net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers) and Error response from daemon: Get "https://registry-1.docker.io/v2/": dial tcp: lookup registry-1.docker.io. I can’t actually ping registry-1.docker.io or hub.docker.com, although I can open hub.docker.com in a browser, so it works for ports 80 and 443, but not some other udp ports.

Perils of Benchmarking

Mon, 06 Jan 2025 00:00:00 +0000

I’ve been containerising my websites, with their servers to make deployment simple and robust, and to move to a CI/CD workflow. Since an install of a production web server is large, I would be running about ten of these containers, and there’s already a good server facing the net and doing the reverse-proxying (NGINX Proxy Manager), I chose to bundle the Busy-Box httpd server with my sites inside the Docker containers.

Moving a domain from Wordpress

Mon, 30 Dec 2024 00:00:00 +0000

I love the convenience of a hosted blog on wordpress.com, but one of the justifications for my ‘investment’ in homelab hardware and learning time was that I’d reduce my spend on hosted platforms by self-hosting them. I’ve already quit Evernote and dropped back to the free plan on Dropbox by building systems to replace them for less money and more data sovereignty. And now, the recent Wordpress drama has made me uneasy about Matt having control of domains I’ve got registered with wordpress.

Updating a deployment on fly.io

Mon, 16 Dec 2024 00:00:00 +0000

I’ve had my external UptimeKuma chugging away on fly.io , for free, for months now, and the container image it was based on was a bit out of date, so I wanted to update it. I hadn’t looked at fly.io for months, and couldn’t really recall what I’d done to create it.

The way this works is that that you create a fly.toml file that sets out the details of your app. From memory I think I used the one from the docs and gave it a unique name, the name of the Docker image, the port, the datacentre location, and the directory for the persisted data. The you run fly deploy from the directory with the toml file (having already installed the CLI tool and logged in) and you’re in business.

Controlling Docker container startup order

Mon, 02 Dec 2024 00:00:00 +0000

A very common scenario when running services in Docker containers is that one service is going to depend on another. The most common example is going to be if you have a service that needs a database - you’re going to want the container running the database to be ready for business before the service that needs it starts. And conversely, when you shut things down, you want to stop the service before you kill the database or you may lose some data.

Fixing TLS for wget in BusyBox

Mon, 25 Nov 2024 00:00:00 +0000

I’ve been containerising my static websites with BusyBox (because it’s small), and in an earlier post showed how to even get the container to update parts of the site by reaching out with wget to download resources from elsewhere and saving them inside the container where we are serving the ‘static’ site from. I’d done this by including a bash script in the container with the wget in a loop with a sleep. Then started the script and the httpd server in the CMD line of the dockerfile.

Fancier Website in a Docker Container

Mon, 18 Nov 2024 00:00:00 +0000

The previous post went over how to bundle a static website into a Docker container. That’s a neat little trick - keeping the entire website and making it trivial to install on a VPS behind Nginx Proxy Manager. It worked great for most of my little websites.

But…

A couple of my websites had very minor ‘dynamic’ content. One was pulling down the local temperature from OpenWeather, then exposing a cut-down version of that as a REST endpoint so all my servers could grab it without me being rate-limited by OpenWeather for abusing my free API key. Another one re-hosted an image that changes a couple of times a day from an unreliable service.

Website in a Docker Container

Mon, 11 Nov 2024 00:00:00 +0000

Having figured out how to use the GitHub package registry, I was a bit inspired by this blog post from Florin Lipan to deliver all my little static websites as Docker containers. I’m not as focused as he is about making them tiny, but I did steal the idea of using BusyBox httpd for serving them, resulting in about 4MB containers. That’s small enough for me, and since they are all very similar, there’s a fair bit of layer reuse going on.

rsync between Synology NAS

Mon, 30 Sep 2024 00:00:00 +0000

A while ago, I devised a complicated system where I could drop files in a web interface running on an LXD container and the files would then magically appear in a directory on a remote NAS in the morning. It turned out to not be very robust, and I gave up on it after a while.

Also, really there should be no need for it - underneath, it was just using rsync to move the files, so why not just do that direct from one NAS to another? Well, mainly because my NASs are all Synology - which I love, and they’ve been great, but in an effort to make them usable by muggles, Synology tend to somewhat complicate things for Linux command line wizards.

Containerised NGINX Proxy Manager & the 502 error

Mon, 16 Sep 2024 00:00:00 +0000

If you’re used to running NGINX Proxy Manager in front of your web apps, and switch to running it in a container, you’re going to need to learn a little about Docker networks to get everything connected. If you just do your regular setup, and direct the proxy for an address to 127.0.0.1:<some port>, it won’t exist, and you’ll visit your page to find the “502 Bad Gateway openresty” message.

dockerfile - CMD vs ENTRYPOINT

Mon, 22 Jul 2024 00:00:00 +0000

There are two entries we often have at the end of a dockerfile (which is the file that tells Docker how an image is to be built).

They are similar in that when the container is launched from an image, these commands will be executed. For example, both of the dockerfiles below will print “Hello World” when run.

doc-entry:

FROM debian:stable-slim
ENTRYPOINT ["echo", "Hello World from ENTRYPOINT"]

doc-cmd:

FROM debian:stable-slim
CMD ["echo", "Hello World"]

User environment variables are not available in cron

Mon, 15 Jul 2024 00:00:00 +0000

I’m used to using the docker-compose.yaml or dockerfile to set environment variables for containers running my apps, but ran into an issue recently where the variable seemed to be set some of the time, but at others it didn’t appear to exist.

I had a script set to run by cron inside the container, and it turns out that the environment variables set for the container are available in the user space, but not in cron, even if running with that user’s permissions. This is probably old news to established Linux users but it threw me for a while. I’d exec into the container and the script would work perfectly, then wait another minute for cron to run it and it would fail 🤦‍♀️ It was exasperated by my discovery that I didn’t know how to console.log debug from inside a container cron job as well - the subject of an earlier post.

Outputting to the console, in Docker, from a cron job

Mon, 08 Jul 2024 00:00:00 +0000

If you’re googling this exact title, you’re probably bumping your head against the same things I was today. I was debugging a completely different project, and needed to print to the console, from a cron job, in a Docker container. Turns out this isn’t as straightforward as I thought.

Foreground cron

Before you even get to the problem space, here’s a tip. If you want to have a cron job running in a container, start cron in the foreground. If you do not, Docker realises nothing is going on, and exits. If you want to keep the container active so your cron jobs get a chance to execute, then start it in the foreground.

Peek inside a Docker image

Mon, 29 Apr 2024 00:00:00 +0000

A ‘dockerfile’ contains all the instructions to build a Docker image. Here’s my first draft for a project I’m working on:

FROM node:20
WORKDIR /usr/src/app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD ["node", "server.js"]

COPY . . is copying all of the files in my project into the working directory of the image so they can be run. Of course we don’t need them all for the app - for example the node_modules directory will be created when we npm install so no need to copy that, and I don’t need all my dot files in the container.

Hosting Your Own Docker Registry

Mon, 25 Mar 2024 00:00:00 +0000

The Docker Personal (ie free tier) plan currently allows one private repository, but even if you want to pay for the next level where you can have unlimited repositories, you may still want to host your own private registry - it’s going to be quicker inside your network, and you won’t run up against Docker’s pull/push limits if you are hammering it with your CI/CD system.

Certbot - removing a domain

Mon, 18 Mar 2024 00:00:00 +0000

I had a number of domains all running on one host when I first set them up with certbot. One started to be serious, so I moved it to another host and ran certbot there. That all worked perfectly, but of course, the old domain is still part of the original certificate, so when I went to renew it, it came up with some errors.

Here’s a few commands that are going to help navigate this situation if you’ve found yourself in the same spot:

Quick & Dirty auth with nginx & Node

Fri, 23 Feb 2024 00:00:00 +0000

One of the basic requirements for any serious web app is a proper users/roles/authentication system - but if you’re just throwing up a utility of some kind on a public IP for testing, and you don’t want it to be abused, then this could be an option. There’s a few components:

Your app. In this demo it’s going to be Node, but it could be Go or whatever your server-side poison is. The app is listening for connections on a non-web port (ie not on 80 or 443), I’m going to use the traditional 3000.
A firewall. That port (in my example 3000) must not be accessible from the internet. It has to be blocked by a firewall.
A web server (I’m using nginx) that enforces basic auth.

I briefly discussed web server basic auth earlier - it’s a system built into the web server that requires a log in for a route, and authenticates it against the credentials in a password file (usually named .htpasswrd) and only serves the content if authenticated.

User Sessions & Cookies in Node

Fri, 09 Feb 2024 00:00:00 +0000

When you are learning app development, you can create all sorts of apps that work for you, but for any serious app, it’s going to need to authenticate users and persist sessions across visits. So much so, that as a professional developer, you’ll probably build that out first - it becomes a sort of boiler plate you always drop in.

In this post, focusing on the server side, using node, express, and particularly express-session, I’ll try and build up from nothing to a reasonable usable user login system explaining the increasing complexity and reasons for it. To follow along you’ll need basic familiarity with node and express.

CSS for React Components

Fri, 12 Jan 2024 00:00:00 +0000

Subscribe to my UX design course 😉

If you think back to HTML as being a document with headings and paragraphs and other semantic bits, it made a lot of sense to have the styles (expressed as CSS) separate to the document. This allows us to change the styles without touching the document - perhaps the user wanted a dark theme, needed the text bigger for accessibility, or perhaps the document was being consumed in some other way - for example a screen reader - so the styles were superfluous.

React - a To Do Example

Mon, 08 Jan 2024 00:00:00 +0000

Since I’m on a roll making different versions of the To Do app, this might be a good time to talk about React . React is one of the giants of front end libraries. It’s based on a few big ideas - and to work effectively in React you need to wrap your head around these.

Overview

Components - when you are developing in React, the starting point of your build is to decompose the user interface in to logical pieces. These components (comprising a mixture of HTML and Javascript) will be the building blocks of your app. In a good composable architecture components are reusable, and that is true for React (there are several sources of components you can pull in). For example, if you created some sort of special slider for your app, it is possible to reuse that quite easily.

htmx - A To Do Example

Fri, 05 Jan 2024 00:00:00 +0000

HTMX is an interesting project to me, and I’ve used it a bit in my large collection of 70% completed side projects, but haven’t really discussed it here. The plan for this post is to talk briefly about what it is exactly, then convert a simple ‘conventional’ (HTML/CSS/Javascript) app to htmx and think about some the differences.

htmx

You could (I recommend you do) read the book about the concepts behind htmx . Carson Gross (the man behind htmx) calls it a book, but its quite the treatise, it could fairly be called a manifesto.

Docker volume backup is more complicated than it should be

Fri, 17 Nov 2023 00:00:00 +0000

When I set up my first Docker container (I think for Uptime Kuma ), I had read around and understood there were two choices for persistent; bind mounts (where the data inside the container is effectively a symlink to a location on the local file system) or name volumes where Docker abstracted that away a bit, so you didn’t have to worry where it was - I sort of understood Docker ‘managed’ it.

Displaying markdown as HTML

Wed, 08 Nov 2023 00:00:00 +0000

In the spirit of over-complicating things, when I wanted to collect all the links to the services on my homelab into one place, I decided I needed to write them in markdown, and have them converted on the fly into HTML by a server. Then when I couldn’t find exactly what I was after (Harp was closest) of course, I decided to write it.

Markdown

Markdown has definitely been having it’s moment over the last couple of years. It’s a simple open format mark-up language that is quite readable in it’s source form. Although it’s now very fashionable as an input for static site generators, most people will have run in to it when adding simple formatting to forum comments or on instant messaging platforms.

Solved DNS Issues - Proxmox, LXC, Ubuntu, Tailscale

Fri, 06 Oct 2023 00:00:00 +0000

I’ve picked up an new TP-Link WAP with Omada, so I wanted to spin up an Ubuntu 20.04 LXC to run the controller software in, and ended up spending a couple of hours figuring out why things where not working.

The initial problem was I was having connectivity issues pulling down the updates for all the packages required. I went down a bit of a tangent because I installed an apt cache the other day, so I was looking for problems there. Eventually I narrowed it down to DNS not working and started A/B testing like this:

Ansible with Secrets

Sun, 13 Aug 2023 00:00:00 +0000

We wrote a nice little Ansible playbook the other day to install nginx on our web servers and ensure it was running. We were able to store the usernames in the hosts inventory file using the ansible_ssh_user variable. Then, we ran the playbook with the command:

ansible-playbook web_installs.yaml --ask-become-pass

This asked us the password to use with the usernames in the hosts file. Luckily that day, it was the same username/password combo to use for sudo on every server. What happens if that’s not the case? Here’s our new hosts file for today. There’s a cool new sysadmin in town - Jane.

nginx in Front of a node.js app

Fri, 04 Aug 2023 00:00:00 +0000

NGINX is a great webserver and reverse proxy - as in it can hand off requests to other web-servers. That’s the situation I want to have set up on my VPS. I want NGINX to handle incoming requests - some of them will just be sorted out by returning static HTML, others (like the weather api I’ve been playing with) need to be handed off to other services to respond to.

HDD Swap on A1278 MacBook Pro

Wed, 10 May 2023 00:00:00 +0000

My MacBook died, I guess about three years ago. It was randomly difficult for a week or so, but then just behaving as if it had no hard drive at all. It’s been in a drawer ever since waiting for me to replace the hard drive and see if I could sell it, which I never quite got to.

I mentioned a while ago that I’d borrowed an old Atom powered HP Mini 110 to play with a Linux desktop machine, partly for fun & learning, and partly for a first-class SPICE experience (also fun). Meanwhile I’ve got an old but still sexy Intel MacBook Pro sitting in a drawer - that doesn’t make sense!

HP EliteDesk 800 G2 Memory Upgrade

Sun, 02 Apr 2023 00:00:00 +0000

The hardware engineering of these corporate world mini-PCs is really nice. I swapped out the RAM today to bump my main machine up to 32GB from 16GB. It was a straightforward task - no screwdrivers, no drama.

To open the machine up, there is a single large screw on the back that can be undone with your fingers - it’s a captive screw, as in it doesn’t fall out - just another nice engineering thought.

Problems mounting network share at boot

Wed, 01 Mar 2023 00:00:00 +0000

I had Jellyfin working nicely in an LXC container in Proxmox, but could not get Tailscale working in the container. Since this is going to be an important part of accessing my media away from home, I decided it was probably worth the extra bulk to run JellyFin in a VM.

Following my own instructions , I had the mount command in the /etc/fstab file so it would persist across reboots. It looked a bit like this:

Accessing a Synology NAS from Linux

Mon, 20 Feb 2023 00:00:00 +0000

I picked up a Synology DS216j NAS from eBay to use for storage for the rapidly growing home lab. The eventual plan is that as well as my VM backups, it will host the media library, and eventually (when this has all proved itself reasonably bullet-proof) my current DropBox contents. That won’t all fit on the 2x2TB drives that the DS216j came with, and I have a pair of 8TBs on hand, but I wanted to set it up and checked it all worked.

External USB Drives in Linux

Sat, 18 Feb 2023 00:00:00 +0000

Many modern Linux distros will auto-mount USB drives - they just pop up in the graphical file manager as users would expect. When you’re running server, older, or smaller versions, that’s probably not going to be the case, and you’ll have to do it old school.

Let’s look at some basics. [lsblk](https://man7.org/linux/man-pages/man8/lsblk.8.html) will list the ‘block’ devices. Your output will almost certainly be a bit different than this.

root@pve:~# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 119.2G 0 disk 
├─sda1 8:1 0 1007K 0 part 
├─sda2 8:2 0 512M 0 part /boot/efi
└─sda3 8:3 0 118.7G 0 part 
 ├─pve-swap 253:0 0 7.7G 0 lvm [SWAP]
 ├─pve-root 253:1 0 39.8G 0 lvm /
 ├─pve-data_tmeta 253:2 0 1G 0 lvm 
 │ └─pve-data-tpool 253:4 0 54.6G 0 lvm 
 │ ├─pve-data 253:5 0 54.6G 1 lvm 
 │ ├─pve-vm--100--disk--0 253:6 0 10G 0 lvm 
 │ ├─pve-vm--101--disk--0 253:7 0 10G 0 lvm 
 │ ├─pve-vm--300--disk--0 253:8 0 8G 0 lvm 
 │ ├─pve-vm--102--disk--0 253:9 0 4M 0 lvm 
 │ └─pve-vm--102--disk--1 253:10 0 32G 0 lvm 
 └─pve-data_tdata 253:3 0 54.6G 0 lvm 
 └─pve-data-tpool 253:4 0 54.6G 0 lvm 
 ├─pve-data 253:5 0 54.6G 1 lvm 
 ├─pve-vm--100--disk--0 253:6 0 10G 0 lvm 
 ├─pve-vm--101--disk--0 253:7 0 10G 0 lvm 
 ├─pve-vm--300--disk--0 253:8 0 8G 0 lvm 
 ├─pve-vm--102--disk--0 253:9 0 4M 0 lvm 
 └─pve-vm--102--disk--1 253:10 0 32G 0 lvm

If you look at the type column, you can see this machine has one disk, with three partitions, and the last partition has a heap of logical volumes. Let’s plug the thumb drive in:

ssh key login on VPS

Sun, 12 Feb 2023 00:00:00 +0000

Due to potential brute force attacks , it’s a good idea to turn off password access via shh and instead rely on ssh keys. In this post, I’ll run through that process.

Generating your key

On a mac (or actually most *ix systems), your ssh keys live in the .ssh directory inside the users home directory. Since it starts with a period, it’s a ‘hidden’ directory. To see it in Finder press

Functions in JavaScript

Mon, 09 Jan 2023 00:00:00 +0000

As with other languages, functions are a little lumps of code with their own scope. They can optionally take some arguments, and optionally return a value.

In JavaScript they often have names, can be passed around as types and have a condensed form suitable for functional programming.

function addNums(a, b) {
 return a+b;
}

console.log(addNums(3,4)) // 7

Scope

Arguments are passed in by value so they have local scope only in the function body.

HTML 001

Fri, 16 Dec 2022 00:00:00 +0000

A HTML file is a text file that can be displayed in a web browser. It is marked up in the sense that tags are applied to the text to signify the purpose of that text in the structure of the document. For example:

<h1>Greetings</h1>
Hello Earthlings

The <h1> tag tells the browser that Greetings is a heading. The heading tag is paired. There’s an opening tag <h1> and closing tag </h1> that let the browser know where the heading starts and ends. Most tags are paired, but there are some unpaired tags such as
which inserts a line break.

Sharing is caring

Sat, 10 Dec 2022 00:00:00 +0000

Continuing on with the demo project from yesterday, in which we used the ImageRenderer class to turn a view into an image, today we want to let the user share it somehow.

Typically, apps have a button using the square.and.arrow.up SF Symbol to share something from the current screen. It’s probably not an accident that it’s literally the first symbol in the app.

Pressing it generally opens the “share sheet” which has options for opening whatever is being shared in another app, printing it, saving it to photos, or whatever.

ImageRenderer()

Thu, 08 Dec 2022 00:00:00 +0000

ImageRenderer () is a SwiftUI class that creates an image from a view. You just initialize it with the view, then extract a cgImage (Core Graphics) or uiImage that can be cast to a SwiftUI Image.

I’ll need a view to work with, so here it is; a crude version of my behaviour ticket.

struct TicketView: View {
 var body: some View {
 ZStack {
 Color(.cyan)
 .frame(width: 300, height: 350)
 VStack {
 Text("Fred Bloggs")
 .font(.largeTitle)
 Text("")
 HStack {
 Text("Putting rubbish in the bin")
 Image(systemName: "trash")
 }
 .foregroundColor(.purple)
 Text("")
 Text("Green Faction")
 Text("")
 Text("")
 Text("\(Date().formatted())")
 }
 }
 }
}

Here it is, with a couple of buttons underneath:

Regex to split a string with two different characters

Wed, 30 Nov 2022 00:00:00 +0000

I’m working on the behaviour tickets app, and wanted a visually functional version to share with stakeholders this week to get some feedback. As usual in this situation, I’m pressed for time so feeling the pressure to take some liberties with code quality that I’ll come back and fix one day.

In a salient lesson of why that’s usually a bad idea, I’ve ended up googling to try and understand regex instead of writing code.

Copying a file via SSH

Tue, 29 Nov 2022 00:00:00 +0000

I have a Raspberry Pi on my home network that I purchased for some project that I can’t actually recall. It gets used for all sorts of completely unnecessary things such as playing with node.js or a private git server. To add to the list of things that I do on pi that could be more efficiently done on my MacBook I wanted to host my sample JSON from yesterday on it.

Mock Data

Mon, 28 Nov 2022 00:00:00 +0000

One of the things we need during app development is some data to play with. It would be unethical for me to use real student data to test my app, even if I wasn’t sharing screenshots of the development here, so I’ll need to build some mock data. The prospect of making 400 rows of data manually does not sound like a good use of time, so I started to think about generating it in Excel. I’d used an online “random address generator” for an earlier project, so I was contemplating pasting that sort of data into Excel workbooks and randomly selecting from it.

iOS 16 Developer Mode

Sat, 19 Nov 2022 00:00:00 +0000

I updated my iPhone to iOS16 this morning, and tonight when I went to run one of my apps, it complained that it needed Developer mode. This is a new, probably wise, way to avoid dodgy apps being loaded on a phone. I don’t know exactly how you’d do that, but then I’m not a black hatted cyber terrorist.

I had to google the setting, it’s in “Privacy and Security” down the bottom, and requires a reboot. When you open the phone there’s another dialog and you need to reauth.

git stash

Sat, 12 Nov 2022 00:00:00 +0000

When I was writing the blog post for the last project, I needed the “before” code to paste into the post. I’d committed that code, so a quick way to go back without losing my changes. I hadn’t committed the new code, so there is a super easy way to accomplish this.

git stash

This grabs the code since the last commit and stashes it away, reverting the directory to the last committed version. I was able to copy the code I needed to the blog post, then to go back to my changes:

git - Rollback to last commit

Tue, 08 Nov 2022 00:00:00 +0000

I’m on Project 12 of the #100Days course, and like a number of earlier “projects” it’s not really a project, but a series of type-along tutorials. Often these have the same format - there’s a base amount of code to provide the setup, then this base is used to try each of the tutorial techniques. At the end of each technique, you delete all the new code you’ve done back to the original setup, and you’re ready for the next one.

@Binding - data between views

Sat, 05 Nov 2022 00:00:00 +0000

In C world, if we want to pass a parameter down into a functional call, and allow the receiving function to change it’s value, we’d pass a pointer to the variable. Something like this:

#include <stdio.h>
#include <stdlib.h>

void increment(int* b) {
 *b=*b+1;
}

int main() {
 int a = 5;
 increment(&a);
 printf("%d", a);
 return 0;
}

// prints '6'

For youngsters, what’s happening is that we’ve set the value of a to 5, then passed the memory address of a into the increment() function. That’s what the @a means.

Codable when the keys don't match

Mon, 31 Oct 2022 00:00:00 +0000

A common issue when working with JSON that you vacuum up from internet APIs will be that the key names in the JSON don’t match your property names. The JSON de facto standard of using snake_case in key names could be one cause, or perhaps you just take variable naming more seriously than the person who wrote the API.

We saw yesterday how using codable and the JSONEncoder in Swift makes moving between an object/struct in the code and a stringish representation of it simple. With a couple of small changes, we can also deal with the mismatched key/property name issue.

Codable & JSON

Sun, 30 Oct 2022 00:00:00 +0000

If we mark a type with the protocol Codable, we’re specifying that this type has the capability of having it’s properties encoded to some format, and decoded back again.

So far in the #100Days this has been used to write and read data in UserDefaults, and to encode an object to send it as a URLRequest, then receive data back and create a new object from it. It’s a handy, powerful feature baked into Swift that just requires the developer to ensure any types that need this functionality comply with the Encodable and Decodable protocols that make up the Codable.

Refreshing SwiftUI Views

Sun, 23 Oct 2022 00:00:00 +0000

SwiftUI does some property wrapper magic to (very efficiently) refresh your views, but what if you want to force a refresh for some reason? Here’s the techniques I’m currently using to do that.

The tricks are below, but just so you can see them in context, here’s the sample app we’re working on. It’s a list of cars so you can keep track of how many of each kind you own. Here’s our data:

Using Swift's map

Thu, 13 Oct 2022 00:00:00 +0000

In Day 39’ s Moonshot tutorial app, Paul uses .map on an array without much comment about what’s going on. I assume this might be a common concept in modern languages, but it was new to me.

First, here’s Paul’s code

 init(mission: Mission, astronauts: [String: Astronaut]) {
 self.mission = mission

 self.crew = mission.crew.map { member in
 if let astronaut = astronauts[member.name] {
 return CrewMember(role: member.role, astronaut: astronaut)
 } else {
 fatalError("Missing \(member.name)")
 }
 }
 }

Mission here contains an array of crew which is a struct with two strings, one of them being name, but self.crew (which belongs to the view we’re in) is an array of CrewMember which is a struct with a role: String and another struct astronaut. That sounds confusing, but essentially, an array of one type is being processed to return an array of another type where there’s a 1:1 relationship between the elements of each array.

SwiftLint

Mon, 10 Oct 2022 00:00:00 +0000

I was watching a Tim Ruscica video about the things that highly effective developers do, and it called to mind a book I read years ago called Code Complete . It is the only book I ever owned that I immediately purchased the new edition when it came out. It was about the meta stuff around programming that is the difference between coding and developing. In particular, it got me invested in source control and testing.

Testing, testing

Sun, 09 Oct 2022 00:00:00 +0000

I have unit testing in my list of goals , and if I’m going to throw this space trimming macOS utility up on the web, now might be a good time to figure out how to add unit tests to a project, how to write them, and how to run them. XCode is well set up for this, so it’s really no drama to do.

Although I haven’t worried with any unit testing up to this point in my iOS/Swift learning, in my previous programming work I did a lot of work with the large calculations involved in translating GPS coordinates and robotic positioning models where errors would be bad - so I’ve written a lot of tests over the years. I’ve also definitely felt the confidence you can dramatically refactor code with when you know the code has a robust test suite. I’m a big fan.

Where's My App?

Sat, 08 Oct 2022 00:00:00 +0000

The iOS apps I’ve been making, can only run in the simulator or on my tethered device (which I haven’t actually tried yet), but the MacOS app I made today, in theory could be zipped up and distributed to the world from my website. At the very least, I wanted to drop it into my Applications folder so I could use it, so I needed to find the .app “file”, and realised I had no idea where it was. If that’s your situation, then here’s the steps you need.

Customizing the default About dialog for MacOS apps

Fri, 07 Oct 2022 00:00:00 +0000

The default Xcode MacOS targeted app has a built in “About” dialog called up from the “About ” menu item in the Mac menu bar. It wasn’t immediately clear to me how to customise this, but after digging through some MacOS apps on GitHub, here’s the answer.

When you app is being built, it looks for the file “Credits.rtf” in the app bundle. If that is found (or “Credits.html” or “Credits.rtfd” ) it’s used to build out the About dialog along with your app icon.

Gitting Xcode to Push

Fri, 30 Sep 2022 00:00:00 +0000

I’m very comfortable with doing all the routine git stuff from the command line, but it was bugging me that I hadn’t for the Xcode integration working. I was able to commit locally with no problem from Xcode, but could not push up to Github. It works fine from the command line, so the error about the change to a stronger SSH authentication didn’t really make sense to me.

Protocols

Tue, 16 Aug 2022 00:00:00 +0000

The evolution of structs into class-like things that can hold properties and methods in Swift raised in my mind “what about inheritance?” - but no: structs in Swift can not use inheritance.

Swift classes implement inheritance, but only from one class; there’s no multiple inheritance. Protocols neatly address both these concerns to a large extent, but perhaps before we look at how they work, we should have a brief diversion into inheritance in C++.

Simple MVVM

Thu, 11 Aug 2022 00:00:00 +0000

MVVM (Model-View-View Model) is an architectural pattern for apps that separates the data (Model) from the user interface (View). The communication between these two parts is facilitated by a View Model.

Model <-> View Model <-> View

Model

The Model is platform independent - we should be able to pluck it out and add it to a different application running on a different platform without any trouble. Any business rules will be part of the Model along with the data. For example, if it’s a rule that every customer has a sales contact, this can be enforced in the Model.

Gitting the hang of it

Thu, 04 Aug 2022 00:00:00 +0000

I spent most of the day learning about, and practicing with git. I’ll list some of the resources at the bottom, but for the moment, this is my understandings / cheat sheet for git. Since this could conceivably turn up in someone’s google search, and slightly less conceivably be of some use, I will come back and edit it if there’s something bad/wrong here. Comments would be great if you think that’s the case.