What are all the allowed `xsi:type` values in the xml's from Magento2

Question

In Magento 2 (almost) all arguments listed in xml files have an attribute xsi:type that determine how the value of the argument is iterpreted.
For example, in di.xml file of the backend module there is this:

<argument name="scopeType" xsi:type="const">Magento\Framework\App\Config\ScopeConfigInterface::SCOPE_TYPE_DEFAULT</argument>

this means that the value of the argument scopeType is the value of the constant Magento\Framework\App\Config\ScopeConfigInterface::SCOPE_TYPE_DEFAULT

or this one

<argument name="template" xsi:type="string">Magento_Theme::root.phtml</argument>

this means that the value of the argument template is the string Magento_Theme::root.phtml.

What are all the possible values of this xsi:type attribute?

Answer 1

I've found all types by checking <xs:extension base="argumentType" in *.xsd files.

lib/internal/Magento/Framework/Data/etc/argument/types.xsd, these are base types:

• "array"
• "string"
• "boolean"
• "object"
• "configurableObject"
• "number"
• "null"

lib/internal/Magento/Framework/ObjectManager/etc/config.xsd, can be found in di.xml files:

• "object"
• "init_parameter"
• "const"

lib/internal/Magento/Framework/View/Layout/etc/elements.xsd, can be found in layout *.xml files:

• "options"
• "url"
• "helper"

Magento/Ui/etc/ui_components.xsd, can be found in UI components' *.xml files:

• "constant"
• "url"

Answer 2

According to my researches, here is what I've found:

The argument interpreter is created in the lib\internal\Magento\Framework\App\ObjectManagerFactory.php :

protected function createArgumentInterpreter(
    \Magento\Framework\Stdlib\BooleanUtils $booleanUtils
) {
    $constInterpreter = new \Magento\Framework\Data\Argument\Interpreter\Constant();
    $result = new \Magento\Framework\Data\Argument\Interpreter\Composite(
        [
            'boolean' => new \Magento\Framework\Data\Argument\Interpreter\Boolean($booleanUtils),
            'string' => new \Magento\Framework\Data\Argument\Interpreter\StringUtils($booleanUtils),
            'number' => new \Magento\Framework\Data\Argument\Interpreter\Number(),
            'null' => new \Magento\Framework\Data\Argument\Interpreter\NullType(),
            'object' => new \Magento\Framework\Data\Argument\Interpreter\DataObject($booleanUtils),
            'const' => $constInterpreter,
            'init_parameter' => new \Magento\Framework\App\Arguments\ArgumentInterpreter($constInterpreter),
        ],
        \Magento\Framework\ObjectManager\Config\Reader\Dom::TYPE_ATTRIBUTE
    );
    // Add interpreters that reference the composite
    $result->addInterpreter('array', new \Magento\Framework\Data\Argument\Interpreter\ArrayType($result));
    return $result;
}

In this code, you can clearly see that different interpreters are used based on the type attribute of the argument \Magento\Framework\ObjectManager\Config\Reader\Dom::TYPE_ATTRIBUTE:

• boolean => \Magento\Framework\Data\Argument\Interpreter\Boolean
• string => \Magento\Framework\Data\Argument\Interpreter\StringUtils
• number => \Magento\Framework\Data\Argument\Interpreter\Number
• null => \Magento\Framework\Data\Argument\Interpreter\NullType
• object => \Magento\Framework\Data\Argument\Interpreter\DataObject
• const => \Magento\Framework\Data\Argument\Interpreter\Constant
• init_parameter => \Magento\Framework\App\Arguments\ArgumentInterpreter (note that this one takes the \Magento\Framework\Data\Argument\Interpreter\Constant as parameter and not the constructor parameter)

Also an extra interpreter is added on the fly to handle array types:

• array => \Magento\Framework\Data\Argument\Interpreter\ArrayType

Note: it seems like the init_parameter type is only used in the app\code\Magento\Store\etc\di.xml to initiate some constants:

<argument name="xFrameOpt" xsi:type="init_parameter">Magento\Framework\App\Response\XFrameOptPlugin::DEPLOYMENT_CONFIG_X_FRAME_OPT</argument>
...
<argument name="isCustomEntryPoint" xsi:type="init_parameter">Magento\Store\Model\Store::CUSTOM_ENTRY_POINT_PARAM</argument>
...
<argument name="runMode" xsi:type="init_parameter">Magento\Store\Model\StoreManager::PARAM_RUN_TYPE</argument>
<argument name="scopeCode" xsi:type="init_parameter">Magento\Store\Model\StoreManager::PARAM_RUN_CODE</argument>