Select2 library solution in Yii2 part 4 – retrieving the data

To continue on from the previous article I wrote about saving the Select2 data …

http://www.jamesbarnsley.com/site/2016/11/07/select2-library-solution-in-yii2-part-3-saving-the-data/

I will now talk about how to the retrieve the stored Select2 data so that the data can be displayed on the front-end Select2 field. Following on from the Task / Countries example, place the following “loadSelect2Items” method inside the Master model or Task model if you did not create a Master model …

The code above can be explained as follows …

  1. Line 3 – return the array of Select2 data using the “array_map” function
  2. Line 4 – store the related entity models name into a variable, in this case that would be the Country models name. This uses the Country relationship that was created in “Part 2” of this article series
  3. Line 5 – store the IDs of the related relationship entity model in the return data, in this case that would be the IDs of the Country model records
  4. Line 6 – find all the records for the model / model property in the “select2_data” table, in this case that would be the Task model and “countries” property

The next step is use the “loadSelect2Items” in the Task model to the load the Select2 data into the “countries” property, place the following inside the “afterFind” method of the Task model …

So that concludes the Select2 library solution for Yii2. I have covered the creation of the necessary database table and the read / write methods for reading / writing the data.

After the initial methods have been setup this solution will provide you with a way of easily putting a Select2 field on your forms that allows for many to many relationships between models with just a couple of line of code.

My new way and correct way of coding Controllers

I have been using frameworks for a number of years with the Yii2 framework being my framework of choice at the present time. When it comes to defining how an application should be structured in terms of Controllers and their methods i was always one to put methods wherever I felt it made sense to put one.

For example my UserController would consist of index, view, create, update, delete, login, logout, lostpassword methods. This made sense at the time. Any action methods that relate to user functionality could go in the UserController. However all the time I was doing this I was aware that some developers and articles on the internet point to the fact that Controllers should only have certain methods within them, namely the standard CRUD methods and nothing else.

So one day I decided to follow that train of thought and start writing my controllers to only have the following methods, index, view, create, update, delete. These methods serve the following purpose …

  1. Index – view all records in a grid view
  2. View – view single record in a detail view
  3. Create – create form and submission code for single record
  4. Update – update form and submission code for single record
  5. Delete – delete a single record

I am aware that I could even get rid of the index and just handle the “view all” and “view single record” through the single Controller method of “view” by checking to see whether an ID parameter has been provided to the method however I thought I would keep them separate.

I am quite pleased by how the new structure has turned out in that it makes my Controller less bulky with code and it gives a much more structured neat and clean feeling to my code and software application.

So you might be wondering what happened to my UserController and the extra methods that where described earlier i.e. login, logout, lostpassword etc. Well using the new system they can be broken down as follows …

UserController

  1. Index – view all users in the system
  2. View – view single users details
  3. Create – create a user
  4. Update – update a user
  5. Delete – delete a user

LoginController

  1. Create – log the user in
  2. Delete – log the user out

LostPasswordController

  1. Create – send the user a link to change the users password
  2. Update – process the clicked link and change the users password

So it is possible to do this, basically the Controllers within the software application now take more definition by having the Controllers named after the type of event the user is wanting to make within the software application and placing less emphasis on the Controllers methods providing the definition. I really like my new way of coding my Controllers and I intent to stick to this method for the foreseeable future.

HTML5 Web Storage Implementation

Recently I have been working on a client project which required the ability to store data from a server on the users local machine. In this case the users local machine was a mobile phone, IOS, Android, Windows etc.

It does not really matter on the platform as it will be stored using the mobile phones web browser and most of the browsers are modern enough to have the new HTML5 Web Storage mechanism.

In actual fact the data will be stored using PhoneGaps implementation of HTML5 Web Storage. PhoneGap is a framework that allows the user to write phone software in HTML5, CSS3 and Javascript.

So for all intents and purposes it is like writing a responsive website that works on mobile phone browsers but is actually compiled and runs like a real native software application. PhoneGap interfaces with HTML5 Web Storage for the purposes of using HTML5 Web Storage mechanism.

So to store the data locally I found WebSQL and HTML5 Web Storage to be my options. Although WebSQL looked perfect for storing and querying the data, it is actually being depreciated and will no longer be in use as a standard in future. So my mind was made up for me in that case.

Web Storage on the other hand seems very straightforward, but this would be the case as it does not include the more complex features of querying the data. Web Storage works by storing name / value pairs. So we can say colour = red, or age = 25, name / value.

Like I said this is straightforward but we cannot say give me all persons over the age of 20 for example there is no querying mechanism.

In actual fact there is no mechanism for even storing multiple persons with ages to begin with. The real structured data is left to the programmer to implement and like wise with querying the structured data.

So what approach did I use?

I decided to store the value of the data as a JSON string and the name would be the table name. So for my project this data needed to be fetched from the web server and stored locally using the Web Storage.

I setup a PHP web server that returned a JSON response upon request via the client. The client did this using JQuery standard Ajax request functions. When I got this JSON response from the server which was basically a dump of a particular database table on the server in JSON format.

I stored it in local storage using the particular database table name for the name value. So in the persons / ages example this would be Person = Encoded JSON string of all data in the server Person table.

So now we have all of data for a particular table from the server stored in local storage. I just repeat this process for all the tables I want to store locally. We now have our data.

But what about querying this data?

Well JQuery does not come, out of the box anyway, with functions for querying JSON data. So a developer might think, I know, I will decode the JSON string and write my own functions for querying this data, possibly by putting the data into foreach loops and returning the records when the data matches the developers expectations. Well that is one way to do it however I am not sure how efficient that would be.

Looping through lots of data just to find single records cannot be very efficient however this is JQuery (Javascript) we are talking about, it is not as if it was designed to do this kind of thing anyway, plus Javascript processing power is becoming more powerful as a whole now in modern day browsers.

It is still not a server side language though and does not query a real database like MySQL which was designed for efficiency, but this is not expected of Javascript anyway.

I do not want to talk about efficiency too much as it is easy to slate querying data this way when a lot of internal libraries might just be doing the same thing under the hood anyway. I cannot imagine there being another way to do it with standard Javascript / JQuery when it comes to the rock bottom.

Anyways enough talk of how querying the decoded JSON data might be handled at a lower level. We as developers have libraries for this kind of thing and luckily someone has written a plugin to do this task anyway called json-sql. Here is the link to the library …

www.trentrichardson.com/jsonsql/

The json-sql library allows the developer to query a JSON string using SQL like syntax. Admittedly it only includes a very small subset of the standard SQL functions but it is most certainly good enough for most purposes, selecting, ordering and where clause. So I used this library to query my JSON data.

So that is pretty much it, the project has a web server which sends JSON responses to the client, data is stored in JSON strings in the client local Web Storage and the data is queried using the json-sql library before being displayed to the user.

This is the way I implemented a server / client, DB synchronized, local storage web software application.

Been using PhoneGap

On one of the latest projects I have been working on the client required that I build a software application that would run natively on multiple phone devices, IOS, Android, Windows and Blackberry.

The client required me to build a native software application for each of these devices because the client wanted to publish the software to the Android and IOS app stores and also because the client wanted the software to be able to run without an internet connection.

Up to yet I have mainly built responsive web applications that can run on a mobile phone through the phones web browser. Due to the client specific requirements this software application could not be done in the same way. If publishing to the app store and running without an internet connection was not a requirement, a web based responsive web application could have still been a viable option.

For previous software applications the responsive web application made sense because those projects where really web based systems that needed the convenience of running through a mobile phone and not a pure phone software application with the specific intent to sell the software as a phone application.

So what is PhoneGap? PhoneGap is a framework that allows developers to construct phone software applications using HTML, CSS and Javascript. After the developer has developed the software application using these languages PhoneGap can then build the phone software to run on multiple phone platforms i.e. IOS, Android plus more.

www.phonegap.com

Obviously this saves tons of time as without PhoneGap or similar frameworks developers would have to construct a software application for each platform. Another advantage of PhoneGap is that it allows web developers to build phone software applications in languages they are use to.

Although PhoneGap has made development easier, one of the drawbacks I have noticed with it is that developers still need to install each SDK. An SDK is a toolkit that allows the compiling of the software application to the phones native device. An SDK has to be installed for each device you want the software application to compile to. Installing each SDK can be a real pain in its own right. Most of the SDKs are installed through the command line and in some cases certain dependencies are required.

Another drawback I have noticed with PhoneGap is that the documentation is not very good. It seems like it is good when you are reading it on the main site or when you are reading it on online tutorials. But then you discover that the documentation you where reading is old and does not work for your version or even that it just simply does not work without you having to do something else which was not mentioned in the documentation. A simple task can look simple when reading the documentation, you do everything the documentation says only to discover it does not work in the way you want it to or even does not work at all.

You must be aware of what type of application you are trying to build and do not try to go beyond its limits when the native coding platform would have been a better choice. PhoneGap seems to be able to do everything the native platforms can do, but in practice it is different or rather you may try to do it but it might have been easier just to code it using the native languages, platforms and tools.

Update: PhoneGap does actually include an online builder which allows you to compile to IOS, Android and Windows without having to install the SDKs locally.

Web programming language to learn first

The other day a friend asked if his nephew could borrow one of my programming books as he wants to start learning programming. I was asked which I would recommend for a beginner and this got me thinking. Which programming language did I learn first? What would be good for a beginner?

Well apart from a brief go at C# whilst at University the first programming language I learned was HTML. Yes I know it is a mark up language and not really a programming language but for the purpose of this article we will class it as one.

So here are my recommendations at the time of writing this article. I would recommend learning HTML5 first and at the same time CSS3. The reason for this is that in my opinion they are easier to learn than a programming language and as a beginner the would be programmer is going to want to keep momentum up and learning something too difficult will bring discouragement.

Learning these two languages are basically a prerequisite to the other languages because even if you where to program a web application part of that will involve creating a user interface and that is generally done in HTML5 and CSS3.

When programming in HTML5 and CSS3 the beginner programmer can see practical results in very little time, neat and cool user interfaces can be created bit by bit without any real complexity and to see these bit by bit changes to the program all the programmer has to do is refresh the web browser.

Also HTML5 and CSS3 only require a web browser and a text editor to get started with. Programming languages generally require installing and configuring applications to get them working.

After learning HTML5 and CSS3 the programmer can move onto something more challenging and what many would consider a real programming language. The next step I recommend is learning Javascript, this is not Java, Javascript and Java are two different languages so do not get them confused.

Learning Javascript will require a whole new paradigm as to what was previously learned in the HTML5 and CSS3. Start with learning the basics, variables, conditions, loops then move onto the more advanced topics like functions and classes. Like HTML5 and CSS3, Javascript only requires the use of a modern day web browser to work and you can get pretty much up and running straight away.

After learning Javascript I would move onto learning PHP and MySQL. This will require you setting up a web server and installing PHP. Certain programs like WAMP / MAMP / LAMP can help with this and give you everything you need to get up and running.

Use the skills you have learned in Javascript and bring them over to PHP. In terms of the paradigm they are similar except PHP is a server side language and Javascript is a client side language. If you can get your head around that everything will be fine, I would not say the jump from Javascript to PHP will be as difficult as the previous jump from HTML5 and CSS3 to Javascript.

You will need to learn MySQL to talk to the database and pull data into your PHP web application. After you have learned these 5 languages the sky is the limit. You will be able to produce full blown web applications.

After learning these five languages I would also recommend learning a PHP framework and a Javascript framework as they will make your programming even easier. For quite some time I coded in standard PHP and Javascript because I did not trust moving to a framework but I can definitely it was one of the best programming decisions I ever made.

You will produce better quality web applications in less time. Also whilst the learning the Javascript framework you will most likely run into Ajax, which is another good concept to learn.

Well that is my recommendations for anyone starting out in the web programming world, give it a go.