How to Create a Lightweight CMS Theme

Prologue

This guide illustrates to create a Lightweight CMS theme, taking default theme of Lightweight CMS as an instance.

Project Structure

Here we list project structure of default theme of Lightweight CMS:

$ cd path/to/themes/default
$ tree --dirsfirst -a -L 1
.
├── assets
├── build
├── partials
├── src
├── theme
├── autoload.php
├── .browserlistrc
├── .eslintrc
├── .flowconfig
├── .gitignore
├── package.json
├── package-lock.json
├── README.md
└── .stylelintrc

assets directory places front end assets of a Lightweight CMS theme. In default theme, the directory includes Babel and Scss code.

Babel code is vanilla JavaScript. Nevertheless, we still transcompile it for compatibility with older browsers. In contrary, Sass code is unusable before compiling to corresponding CSS one.

build directory composes of Gulp build scripts. If you want to employ other build automation system, you require to write your own.

theme and partials are layouts of default theme. To simplify the code base, these layouts are written in PHP instead of other template language.

src are small PHP scripts used by this theme. Mandatory functions for a Lightweight CMS theme are included in these scripts as well.

.browserlistrc, .eslintrc, .flowconfig and .stylelintrc are configurations for front end assets of default theme.

None of these are mandatory for a Lightweight CMS theme. The only required file is autoload.php in root path of a Lightweight CMS theme. See next section for more information.

autoload.php

Project structure of a Lightweight CMS theme is very liberal. autoload.php is the only mandatory file for a Lightweight CMS theme. The script should always be located in root path of a Lightweight CMS theme. You may either implement required functions within it or load another PHP script.

Required Functions in a Lightweight CMS Theme

loadHome() Function

The essential function to load the layout for home page in a Lightweight CMS site. It receives no parameter. Theme creators are responsible to load a layout for home page properly.

Here is a sample code:

function loadHome ()
{
    # Get the root path of default theme of Lightweight CMS.
    $sep = DIRECTORY_SEPARATOR;
    $rootDirectory = __DIR__ . $sep . "..";

    require $rootDirectory . $sep . "theme" . $sep . "home.php";
}

It is recommended to use require instead of include here because it should be an error unable to load a layout properly.

loadSection() Function

The necessary function to load the layout for sections in a Lightweight CMS site. In a similiar fashion, it receives no parameter. Here shows an example:

function loadSection ()
{
    # Get the root path of default theme of Lightweight CMS.
    $sep = DIRECTORY_SEPARATOR;
    $rootDirectory = __DIR__ . $sep . "..";

    require $rootDirectory . $sep . "theme" . $sep . "section.php";
}

Lightweight CMS doesn't distinguish between top sections and nested ones. Therefore, only one function is needed here.

loadPost() Function

The mandatory function to load the layout for posts in a Lightweight CMS site. No parameter is needed. Here shows a sample code:

function loadPost ()
{
    # Get the root path of default theme of Lightweight CMS.
    $sep = DIRECTORY_SEPARATOR;
    $rootDirectory = __DIR__ . $sep . "..";

    require $rootDirectory . $sep . "theme" . $sep . "post.php";
}

loadPage() Function

The needed function to load the layout for pages in a Lightweight CMS site. No parameter is required. Here shows a sample code:

function loadPage ()
{
    $sep = DIRECTORY_SEPARATOR;
    $rootDirectory = __DIR__ . $sep . "..";

    require $rootDirectory . $sep . "layout" . $sep . "page.php";
}

loadAssets($dest) Function

The function to copy assets in a theme to a destination path specified by Lightweight CMS. Unlike other functions here, it receives one parameter, which represents a destination path.

Default theme of Lightweight CMS utilize Sass and Babel as its front end stacks. Code written in the two languages requires compilation before deploying to production environments.

Here is the function used by default theme of Lightweight CMS:

function loadAssets ($dest)
{
    # Save the path of old working directory.
    $oldDirectory = getcwd();

    # Get the root path of default theme of Lightweight CMS.
    $sep = DIRECTORY_SEPARATOR;
    $rootDirectory = __DIR__ . $sep . "..";

    # Move to theme directory.
    if (!chdir($rootDirectory)) {
        # Move back to old working directory.
        chdir($oldDirectory);

        throw new \Exception("Unable to change working directory to theme directory");
    }

    # We don't update NPM packages because they are merely for build automation.
    if (!(file_exists("node_modules") && is_dir("node_modules"))) {
        if (!system("npm install")) {
            # Move back to old working directory.
            chdir($oldDirectory);

            throw new \Exception("Unable to install NPM packages");
        }
    }

    # Compile assets.
    #
    # Not every theme invoke the same command to compile assets.
    #  Modify it according to your own situation.
    if (!system("npm run prod")) {
        # Move back to old working directory.
        chdir($oldDirectory);

        throw new \Exception("Unable to compile assets");
    }

    # Copy assets recursively.
    try {
        $publicDirectory = $rootDirectory . $sep . "public";

        # xCopy is a utility function in Lightweight CMS.
        #  It will copy directories and files recursively.
        \LightweightCMS\Core\xCopy($publicDirectory, $dest);
    }
    catch (Exception $e) {
        # Move back to old working directory.
        chdir($oldDirectory);

        throw $e;
    }

    # Move back to old working directory.
    chdir($oldDirectory);
}

You should not copy and paste the code here to your own theme. Instead, modify it according to your situation.

Required Layouts

Here we list sample layouts used in Lightweight CMS themes:

• Layout for home page
• Layout for sections
• Layout for posts
• Layout for pages

Check exposed variables in these layouts here.

Best Practices to Write a Lightweight CMS Theme

Avoid Namespace

Rounter of Lightweight CMS views these required functions as global ones. Therefore, don't add any namespace in required functions.

Load Third-Party Libraries

You may need features other than those in the core library of Lightweight CMS. If you need any third-party library, you should load them in the main loader, i.e. autoload.php in root path of a Lightweight CMS theme. Furthermore, you should write code to detect and compile you dependencies automatically.

Write Build Scripts for Assets

Gulp build scripts in default theme of Lightweight CMS is not a required part of a Lightweight CMS theme. You may delete them, adding your build scripts for front end stacks of your theme. Automate your compilation so that you can invoke the whole process in a single command.