About Elvis Ciotti

Founder and Software Engineer at Software Engineering Solutions (UK), currently working as a Senior PHP Developer for the UK Ministry of Justice.

Stand on the shoulders of giants, and export your code

stand shoulder giantAmong the many software principles to adopt, like KISS eYAGNI, another important one is DRY (Don’t repeat yourself), IMO connected to the Standing on the shoulder of giants principle. In other words: Great people already faced your problems, solved them elegantly and also published their solution. So why not using highly skilled people’s solutions instead of developing yours ?
Unless you do things for learning, it’s more efficient to re-use things and avoid reinventing the wheel. Is, therefore, important to learn how to contribute to export and distribute some code to the public. Below, a list of some libraries I’ve exported from some projects of mine because I thought I’d use them in the future, or somebody else would need them.

Currency converter

A few years ago I developed a component to convert GBP into EUR for a client who needed an auction website and price filtering in different currencies. No PHP library was available at the time (not sure there still is one), so I’ve developed this unit-tested parser able to read values from the European central bank feed. I’ve used it a couple of time since then, so it was a good idea exporting it. If I need to convert currencies, it’ll take minutes to add this to the project. Note: the library doesn’t download and cache the feed on purpose. I prefer to have repositories doing one thing only. Downloading and caching is a responsibility of the caller, and it could be doctrine caching and a simple PHP file_get_content or guzzle call, depending on what you already use in your project.

Mockery stub chain

Mockery (PHP stubs framework for testing) allows to mock chains of called methods, but no arguments can be specified. If your arguments are strings or integers, you can use this simple extension and write the same assumptions in a simpler way.

Twig text extension

I couldn’t find a simple twig extension to limit some text by the number of words (without truncating them), and – in case they are truncated – add a suffix like “continue …”. Also, there was nothing to remove accents (useful to Slugify), so I created this unit-tested one, where I’ll add more general purpose Twig filters in the future.

Array collection

A simple extension of doctrine array collections that already work great, but a.t.m. misses functionalities like sorting, create a new one from a merge of multiple arrays/collections, get not empty values.
Very simple and worth exporting. It’s unit tested, so I next time I need to work with a ArrayCollection, I’ll add this repo to the composer file and save time. Besides, any improvements will get saved into the repository itself, and not into a private project that might be abandoned, and therefore not lost.

WooCommerce layered nav sort

Simple WordPress Woocommerce plugin to order woocommerce layered navs filters by order descending. Took minutes to implement.

Better google tasks

Google Tasks web client, displaying all the lists on one page, functionalities to drag and drop tasks from one list to another. Written with AngularJs and Silex. I’ve abandoned this project due to some priorities, but some parts of it could be useful for similar projects. Sorry, no demo available

Text spinner

There are free language dictionaries on the web, but no open source library to parse them.
I’ve created one, that can be used for auto text spinning or suggesting synonyms.

How to create DEB packages for ubuntu/debian

linuxTo create a DEB package, you just need to create a directory with the files, respecting the same structure starting from “/”, plus a couple of files with the configuration.

The command dpkg –build will then create the DEB files that you can install with dpkg -i mysqldb2html.deb.

For detailed, instructions, read this article on ubuntuforums.org.

For an example of application of mine, just packaging a single script, click here

ZF2 subforms usage and validation

zf2Differently from Zend Framework 1, I couldn’t find any good documentation about the usage of subforms in Zend Framework 2.
After a bit of investigation, I understood how to use them.
When the subforms extend the `Fieldset` ZF2 class, they can be added to the form with a name, and that name (e.g. subform1 and subform2) will be used with getData() and setData() as a key of the subform data array.
The validation can stay in each related subform, the isValid() ZF2 Form will recursively validate all the subforms.
Example:
A `MainForm` contains two subforms (named `subform1` and `subform2`) of the same class `SubForm`.
Once filled in, getData() will return the following. Equally, the same array structure will fill in the related fields.
    $data = array(
      ‘formElement’ => ‘…’,
      ‘subform1’ => array(
         ‘first’ => ‘…’,
         ‘second’ => ‘…’,
      ),
      ‘subform2’ => array(
         ‘first’ => ‘…’,
         ‘second’ => ‘…’,
      )
    );
Here the code:

How to create mobile apps with PhoneGap

Making a “hello word” application for my android mobile phone was in my Todo-list for ages, and last night (the flu blocked me home) I spent a couple of courses challenging myself to develop a mobile application starting from scratch (including downloading and setting up the needed tools).

I decided to use PhoneGap, at which I had a look last spring and it soon looked great: using CSS and JavaScript to develop cross-platform (Android, iPhone, windows mobile).

Tools

I timeboxed my hack-night and I kept things super simple, opting for the PhoneGap desktop app to run the server (the mobile phone connects to it, downloads and execute the code in real-time, in beta version and sometimes not refreshing as expected) and for the  online compiling tools (free up to one application, a bit slow but they do the job).

Issues

The only problem I had was the layout. The PhoneGap CSS layout didn’t suit my needs and I started with a new one, ending up spending most of the time with font size and media queries to render the application properly on different devices (the app executed via the desktop app rendered differently from the compiled APK one on my Nexus 4).

Coding !

This was my “hello world” application so I kept it simple, without any complicated phone API interaction, just a calculator for runners (insert distance and time, calculate velocity).

running tools android appApart from understanding where to load the events (I had two different ways to do that, and none of them worked as expected, I think due to a non-back-compatible old event system), the JavaScript code worked like a charm on my local browser as on the mobile phone.

Download & repo

If you want to give at try, download the APK. Source code on Github. It asks for lots of permissions, but don’t worry, I just haven’t had the time to take out the one I didn’t need from the default settings.

The app compiled in a 480Kbsize APK file, that is good considering the app wasn’t written in the native Java language, and I haven’t even spent a second trying to strip out the unnecessary stuff (nobody cares about size, do you ? ;-))

 

Nice, uh? take a coffee and impement your own !

 

 

 

 

Quick intro to Postgres for developers

postgresIn this article, a quick guide to the most commonly used Postgres commands

INSTALL

sudo apt-get install postgresql postgresql-contrib

ADMIN OPERATIONS

Create superuser from the commad line

sudo -u postgres createuser –superuser digideps

Create database from command line

sudo -u postgres createdb newDatabaseName

Login via command line (postgres is the default root user)

sudo -u postgres psql [dbname]

DEVELOPER OPERATIONS / QUERIES

Describe table1

d+ table1;

Change password of the postgres user

password postgres

Grant permission on db1 to user1

grant all privileges on database db1 to user1

List databases

l

List users

du

List tables in a db

dt

IMPORT/EXPORT

Export db snapshot

sudo -u postgres pg_dump dbname —clean > dump.sql

Import db from snapshot

sudo -u postgres psql dbname < dump.sql

The simplest Observer design pattern example

A few days ago I got involved in a chat about the usage of Object-oriented design patterns. I brought up the problematic of their usage when not needed, that ends up in adapting the code to the pattern and altering it, risking to increase its complexity. I mentioned an example of usage of the Observer design pattern, that I’ve seen used even where one object A (Subject) just needed to keep an array of reference of objects B (Observers), but B didn’t actually need to refer back to A.

From Wikipedia: The observer pattern is a software design pattern in which an object, called the subject, maintains a list of its dependents, called observers, and notifies them automatically of any state changes, usually by calling one of their methods.

In this post, I’ll expose a case where the usage of that pattern is very simple to understand: a Newsletter system, with senders (Subject) and subscribers (Observers).

In this example, we have two users, John and Mike who both subscribe to the NewsletterSender (Subject). When the email is sent, both are notified by NewsletterSender::notifySubscribers() that iterates the users and call their update() passing its reference. Via this reference, the users will then be able to call the getter to read the email. So, John and Mike will both receive the reference to the NewsletterSender, John will print out the email text, but Mike only decides to say that there is an email (different implementation).

See the comment near each method with the classes and method names of the corresponding PHP interfaces SplObserver and SplSubject

script to modify DB values filtering by column and rows

One of my clients recently needed to implement an application-level encryption for some existing applications.

Unfortunately, the design pattern used for the database layer obliged me to write an independent script to browse the database and encrypt the data for each user using a user-specific two-way encryption key.

So, I ended up writing a simple utility class that applies a user-defined function (modifies) to the defined columns and records (via a filter query) of each database table.

It can be used for any relational database server supported by PDO (MySQL, SQL Server, MySQL, Oracle). I’ve only used it with MySQL but it should work smoothly with all the others.

Repository:
Db modifier https://github.com/elvisciotti/DbModifier

An example of usage is in the README, hope it’s clear enough.

You can basically use this to mass editing Db records with a function that is NOT easily implementable with a simple MySQL Query, e.g. encrypt the data with a custom PHP function.

File Upload from HTML form: client and server validation for maximum size

File uploading normally requires client validation (mainly as a UI improvement) and server validation (in case the client validation is bypassed/hacked).

The code

<input type="hidden" name="MAX_FILE_SIZE" 
 value="2621440"/>

only imposes a soft limit (in bytes) on the server side, therefore not a good practice since it can be altered by the user. The solution I adopted is composed by a server side validation AND a client validation (in JavaScript, mainly for a better user experience since it can be easily hacked as all the other JS solutions)

Client validation (JavaScript)

The idea is accessing the files JS property of the input field and read the file size on the ‘change’ event (when a file is selected by the user). If the selected files exceed the max size, I simply display a clear user warning and disable the submit button. I’ve created a generic script that automatically listens to the change event for any file upload element, and reads the max upload size in bytes from the MAX_FILE_SIZE HTML input hidden element in the same form.

Server side validation (PHP)

Just set the desired value for ‘upload_max_filesize’ and ‘post_max_size’ PHP settings (php.ini). Alternatively, if you need application specific settings and you use apache as web server, add the following lines into the .htaccess in your web root

php_value upload_max_filesize 25M
php_value post_max_size 25M

Doctrine 2 + zf2 working with both SQL server and MySQL

The web application I’m working on (PHP 5.3, zf2, Doctrine2, on MySQL/Apache) has recently raised interest from the clients and it now needs to be installed on their premises, often a Windows server( arghhh!). That meant we had to make the application compatible with both MySQL and SQL-Server.
Here I summarize the changes and the solutions we adopted.
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