Git: Compare Differences Between Branches

7th March 2021 - 4 minutes read time

The git diff command will allow you to view the differences in your workspace. This can be used in a number of ways to look at the differences in a file, in a branch or between two branches.

For example, you can view the differences in your current workspace by just running git diff on its own. By supplying a file you can look at the differences in just that file.

To compare the difference between one branch and another you use '..' to separate the branch names. For example, to look at the differences between the head of the 'main' branch and the head of a feature branch use this syntax.

git diff main..feature_branch

This can often be quite noisy, especially on large projects, so to check just one directory between two branches you can add the directory path to the command.

PHP: Find An Array Sequence In An Array

6th March 2021 - 3 minutes read time

I was looking for a function that searched an array for another array, and after not finding one I decided to write it. What I was looking for was a function that took a smaller array and searched for that exact sequence of items in a larger array. As it happens, PHP does have a number of array search functions, but they didn't produce the correct result.

The array_search() function does accept an array as the needle to be searched for, but this does a multi-dimensional search instead. I also saw some techniques using array_intersect() or array_diff(), and although these functions were able to find one array inside another I was interested in the sequence. 

The implementation of the function contains a two loops, one for going through the haystack array and one for the needle array. If the number of matches found equals the number of items in the needle array then the function returns true.

Here is the sequence_in_array() function.

PHP Live Regex

1st March 2021 - 3 minutes read time

When creating regular expressions for PHP I tend to use the awesome tool PHP Live Regex.

This tool has really helped me over the last couple of years to create regular expressions for many of the projects I've been working on. Everything from validation functions to formatters that use regular expressions have had their expressions worked out using this tool. I even use it for testing one off expressions where I just need to find/replace in a file.

PHP Strict Types

28th February 2021 - 6 minutes read time

In December 2015, PHP 7 introduced scalar type declarations and with it the strict_types flag. This flag can be used to enforce the type of value passed to functions. Although I have seen it in action in the past, I have never actually used it before so I decided to look into it a little to see what it was about.

For some background, types are not strictly enforced in PHP. This means that it is not only possible to swap the type of a variable from one type to another, but it is also possible to swap a variable of one type to another depending on the context being used. Programmers getting started in PHP will spot this when attempting to print out a boolean value as this will be cast to an integer before being printed out. This means that when attempting to print 'true' PHP will instead print out '1'. PHP will automatically coerces values to be one type to another when passing values to functions.

Drupal 9: Cascading Ajax Select Forms

14th February 2021 - 14 minutes read time

Tying together different select elements in a form is done with very little effort thanks to the ajax and states system built into Drupal 9. This means that any Drupal form can have a select element that shows and updates options into another select element within the same form. Using this system you can create a hierarchical system where one select will show and populate another select element with items dependent on the first. This is great for giving the user the ability to drill down into options that are dependent on each other. As the user selects the first select element the second select element will populate with data and be shown on the screen.

Displaying Tables As Block Elements On Mobile

2nd February 2021 - 5 minutes read time

The experience of using tables in websites whilst on a mobile can be pretty poor. Things tend to get a bit squashed and displaying the information can be a challenge just to fit the table onto the screen.

I was recently faced with a similar problem where I had a particular design in mind for the mobile version of the table. The solution I found was base based on some responsive table designs from CSS-tricks. I'm certainly no designer, but the what I created worked for the situation I was trying to solve.

The basic idea is that instead of treating the table like a table, change all of the table elements to block elements when displaying on mobile. This meant that when viewing the table in a mobile view it would be rendered in a different way, allowing it to be shown in a mode that was more mobile friendly.

Let's use the following table filled with some data.

Drupal 9: Preventing Enumeration Attacks

29th January 2021 - 19 minutes read time

A recent Wired article about the Parler data hack talked about how a hacker group was able to steal publicly available information from the Parler website using an Insecure Direct Object Reference (IDOR) or enumeration attack. This type of attack involves a hacker looking at the structure of the site and attempting to guess the next available resource by looking at the URL. Apparently, terabytes of Parler's data was downloaded by simply enumerating through the ID's of their publicly available posts.

PHP instanceof Operator Tips

26th January 2021 - 8 minutes read time

The instanceof operator in PHP is great at making sure you are looking at a type of object before acting on it. Whilst it's straightforward to use on its own, using it can lead to some undesirable side effects.

As a basic example, let's create a couple of interfaces and classes to show the instanceof operator in action. Rather than just have some test names I am using object names that you might find in a system. This consists of User and Order that might form part of a commerce system.

Steganography With Images In PHP

15th January 2021 - 18 minutes read time

Steganography is the practice of placing a secret message inside another message and only by looking at the original message in a different way can the hidden message be seen. This might be as mundane as writing a page of text and hiding a message in the text using the first letter of every sentence. Only by collecting the first letter of each sentence together can the hidden message be seen and read.

Modern steganography is defined as hiding a message (or file) inside a file. For example, you might look at an image and see an image, but if a message has been hidden you would also be able to extract it if you know where to look.

Drupal 9: Auto Injecting Paragraph Forms On Node Edit Pages

10th January 2021 - 9 minutes read time

I tried to do something the other day that I thought would be quite simple, but turned out to be really hard to get my head around. I had a Drupal 9 site with Paragraphs installed and I wanted a user to click a button on the node edit form and inject a particular Paragraph into a Paragraph field.

I found 2 solutions to this problem that solve it in slight different ways.

Piggy Back On Existing Events

After my initial struggles over trying to get this to work I decided to use a piggy back method. This essentially listens for the user interaction and then triggers the Paragraph add event that inserts the Paragraph into the field. The user interaction I was listening for was a user selecting different elements in a select list.

To get this working I added some JavaScript to the page, attached to the select list field called "field_type".