Payment method facade

Payment facade it is an instance of Payment Adapter configured with virtual types and allows to process payment actions between Magento Sales Management and payment processor.

Add the dependency injection (DI) configuration for payment method facade in your %Vendor_Module%/etc/di.xml.

The following sample is an illustration of such configuration (app/code/Magento/Braintree/etc/di.xml#L10):

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<virtualType name="BraintreeFacade" type="Magento\Payment\Model\Method\Adapter">
    <arguments>
        <argument name="code" xsi:type="const">Magento\Braintree\Model\Ui\ConfigProvider::CODE</argument>
        <argument name="formBlockType" xsi:type="string">Magento\Braintree\Block\Form</argument>
        <argument name="infoBlockType" xsi:type="string">Magento\Braintree\Block\Info</argument>
        <argument name="valueHandlerPool" xsi:type="object">BraintreeValueHandlerPool</argument>
        <argument name="validatorPool" xsi:type="object">BraintreeValidatorPool</argument>
        <argument name="commandPool" xsi:type="object">BraintreeCommandPool</argument>
    </arguments>
</virtualType>

The following arguments must be configured (all arguments are mandatory):

Value handlers pool

Let’s look closer at the value handlers pool of a payment method. This pool enables you to set payment configuration that is based on certain conditions.

For example, the can_void configuration option might depend on payment transaction status or paid amount. The following sample shows how to set the corresponding configuration (app/code/Magento/Braintree/etc/di.xml#L296):

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<virtualType name="BraintreeValueHandlerPool" type="Magento\Payment\Gateway\Config\ValueHandlerPool">
    <arguments>
        <argument name="handlers" xsi:type="array">
            <item name="default" xsi:type="string">BraintreeConfigValueHandler</item>
            <item name="can_void" xsi:type="string">Magento\Braintree\Gateway\Config\CanVoidHandler</item>
            <item name="can_cancel" xsi:type="string">Magento\Braintree\Gateway\Config\CanVoidHandler</item>
        </argument>
    </arguments>
</virtualType>

Pay attention, that you must always specify the default handler. In the example it is config reader for Braintree:

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<virtualType name="BraintreeConfigValueHandler" type="Magento\Payment\Gateway\Config\ConfigValueHandler">
    <arguments>
        <argument name="configInterface" xsi:type="object">Magento\Braintree\Gateway\Config\Config</argument>
    </arguments>
</virtualType>

In your configuration you can use default Magento\Payment\Gateway\Config\Config. Or you can add a custom config interface. It must implement the Magento\Payment\Gateway\ConfigInterface interface.

Magento\Payment\Gateway\Config\Config can read configuration by payment method code, so is useful to use it or extend it for your own purposes.

And Magento\Braintree\Gateway\Config\Config reads configuration from database or payment config file.

Other handlers contain some logic, for example, can_cancel option is the same as can_void and depends on whether the order has paid amount (invoiced).

Your custom handlers must implement the Value Handler interface.

Validators pool

You can configure the pool of validators, which allows processing various payment method validations. Below are the examples of such validators:

• country — checks if billing country is allowed for the payment method
• currency — checks if the selected currency is allowed for the payment method
• availability — checks if the payment method is available
• global — the validation that is called before placing an order

A custom validator should implement the \Magento\Payment\Gateway\Validator\ValidatorInterface. In the most cases, it is enough to extend the \Magento\Payment\Gateway\Validator\AbstractValidator and create an implementation of the validate method:

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class CountryValidator extends AbstractValidator
{
    /**
     * @inheritdoc
     */
    public function validate(array $validationSubject)
    {
        $isValid = true;
        $storeId = $validationSubject['storeId'];

        if ((int)$this->config->getValue('allowspecific', $storeId) === 1) {
            $availableCountries = explode(
                ',',
                $this->config->getValue('specificcountry', $storeId)
            );

            if (!in_array($validationSubject['country'], $availableCountries)) {
                $isValid =  false;
            }
        }

        return $this->createResult($isValid);
    }
}

Then, the newly created validator needs to be added to the global pool of validators:

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<virtualType name="BraintreeValidatorPool" type="Magento\Payment\Gateway\Validator\ValidatorPool">
    <arguments>
        <argument name="validators" xsi:type="array">
            <item name="country" xsi:type="string">Magento\Braintree\Gateway\Validator\CountryValidator</item>
        </argument>
    </arguments>
</virtualType>

What’s next

• Payment info rendering in Admin checkout
• Add a gateway command