Detailed explanation of the usage of Yii2 theme (Theme)

This article describes the usage of the Yii2 theme (Theme). Share it for your reference, as follows:

First, let’s take a look at the main configuration method:

'components' => [
  'view' => [
    'theme' => [
      'pathMap' => ['@app/views' => '@app/themes/basic'],
      'baseUrl' => '@web/themes/basic',
    ],
  ],
],

The theme function in Yii is mainly implemented by the yii\base\Theme class. Its main idea is: first define a one-to-one string mapping array, and then replace the given string according to the mapping relationship in the array.

There are the following mappings:

$pathMap=[
    '@app/a' => '@app/aaa',
    '@app/b' => '@app/bbb',
    '@app/c' => [
        '@app/ccc/xxx',
        '@app/ccc/yyy',
      ],
];

For the string @app/a/site/, from the above mapping relationship, we can see that @app/a is replaced with @app/aaaa, and the result is @app/aaa/site/.

But be aware that this is not the final result. Since it is an operation on the file path in Yii, if the file @app/aaa/site/ exists, this path will be returned, otherwise the original path will be returned, i.e.: @app/a/site/

If there is a string @app/c/site/, since the above mapping knows that @app/c corresponds to 2 replacement items, Yii will replace it in sequence from the previous time, and will be @app/ccc/xxx/site/. If this file exists, return this path, otherwise continue to replace it.

If all replacement results do not have the corresponding file, then the original path will be returned to the end.

There is one advantage of writing multiple replacement target values ​​at the same time: implementing theme inheritance.

Now there is a default theme default. If you want to add a black theme now, there are two ways to achieve it.

The first type: copy all the views in the default into the blank directory.

The second type: just copy one layout file into the blank directory, and then modify the overall color in the layout file. Then set as

$pathMap=[
    '@app/c' => [
        '@app/ccc/blank',
        '@app/ccc/default',
      ],
];

You can see the benefits. If no file is found in blank, it will be searched from the default, which means that the files in blank will overwrite the files present in the default, thus realizing the inheritance of the theme.

Properties in the topic:

$pathMap: This is used to set the replacement mapping relationship.

'pathMap' =>[
    '@app/views' => [
        '@app/themes/blank',
        '@app/themes/default',
    ],
    '@app/modules' => '@app/themes/default/modules',
    '@app/widgets' => '@app/themes/default/widgets'
],

These three apply themes to views, modules and widgets respectively.

$baseUrl: This is used to set the url of the resource to be accessed (no "/" at the end)

$basePath: Set the file directory where the resource is located

Methods in the topic:

public function init()

public function init()
{
    parent::init();
    //If the $pathMap mapping is not set, use $basePath.    if (empty($this->pathMap)) {
        /*
          * If $basePath is not set, an exception occurs.
          * In other words, at least one of $pathMap and $basePath should be set. If both are set, use $pathMap first.
          */
      if (($basePath = $this->getBasePath()) === null) {
        throw new InvalidConfigException('The "basePath" property must be set.');
      }
      //Set the mapping relationship between the path of the current module and $basePath      $this->pathMap = [Yii::$app->getBasePath() => [$basePath]];
    }
}

public function applyTo($path)

//This is to replace the string of $path according to the mapping relationship defined in $pathMappublic function applyTo($path)
{
    //Use unified replacement of "/" and "\" in the path    $path = FileHelper::normalizePath($path);
    foreach ($this->pathMap as $from => $tos) {
       //Map the source in the array (old value)      $from = FileHelper::normalizePath(Yii::getAlias($from)) . DIRECTORY_SEPARATOR;
      //If there is a replacement old value in $path      if (strpos($path, $from) === 0) {
        $n = strlen($from);
        //Cycle the target value,        foreach ((array) $tos as $to) {
          $to = FileHelper::normalizePath(Yii::getAlias($to)) . DIRECTORY_SEPARATOR;
          //Replace $from in $path with $to          $file = $to . substr($path, $n);
          //If it is a file, return it directly          if (is_file($file)) {
            return $file;
          }
        }
      }
    }
    return $path;
}

For more information about Yii, readers who are interested in this site can view the topic:Yii framework introduction and common techniques summary》、《Summary of excellent development framework for php》、《Basic tutorial on getting started with smarty templates》、《PHP object-oriented programming tutorial》、《Summary of usage of php strings》、《PHP+mysql database operation tutorial"and"Summary of common database operation techniques for php》

I hope that this article will be helpful to everyone's PHP programming based on the Yii framework.