Add Backend model for Fetch Tag limit config

Author: wigman

src/Model/System/Config/Backend/FetchTagLimit.php

@@ -0,0 +1,73 @@
+<?php
+declare(strict_types=1);
+
+namespace IntegerNet\AsyncVarnish\Model\System\Config\Backend;
+
+use Magento\Framework\App\Cache\TypeListInterface;
+use Magento\Framework\App\Config\Value;
+use Magento\Framework\App\ObjectManager;
+use Magento\Framework\Data\Collection\AbstractDb;
+use Magento\Framework\Escaper;
+use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\Framework\Exception\LocalizedException;
+use Magento\Framework\Model\Context;
+use Magento\Framework\Model\ResourceModel\AbstractResource;
+use Magento\Framework\Registry;
+
+/**
+ * Backend model for processing Varnish Fetch Tag Limit settings
+ *
+ * Class HeaderLength
+ */
+class FetchTagLimit extends Value
+{
+    /**
+     * @var Escaper
+     */
+    private $escaper;
+
+    /**
+     * Ttl constructor.
+     * @param Context $context
+     * @param Registry $registry
+     * @param ScopeConfigInterface $config
+     * @param TypeListInterface $cacheTypeList
+     * @param AbstractResource|null $resource
+     * @param AbstractDb|null $resourceCollection
+     * @param array $data
+     * @param Escaper|null $escaper
+     */
+    public function __construct(
+        Context $context,
+        Registry $registry,
+        ScopeConfigInterface $config,
+        TypeListInterface $cacheTypeList,
+        ?AbstractResource $resource = null,
+        ?AbstractDb $resourceCollection = null,
+        array $data = [],
+        ?Escaper $escaper = null
+    ) {
+        parent::__construct($context, $registry, $config, $cacheTypeList, $resource, $resourceCollection, $data);
+        $this->escaper = $escaper ?: ObjectManager::getInstance()->create(Escaper::class);
+    }
+
+    /**
+     * Throw exception if HeaderLength data is invalid or empty
+     *
+     * @return $this
+     * @throws LocalizedException
+     */
+    public function beforeSave()
+    {
+        $value = $this->getValue();
+        if ($value < 0 || !preg_match('/^[0-9]+$/', $value)) {
+            throw new LocalizedException(
+                __(
+                    'Fetch tag limit value "%1" is not valid. Please use only numbers equal or greater than 0.',
+                    $this->escaper->escapeHtml($value)
+                )
+            );
+        }
+        return $this;
+    }
+}

src/etc/adminhtml/system.xml

@@ -19,7 +19,7 @@
                     <field id="varnish_fetch_tag_limit" type="text" translate="label comment" sortOrder="110"
                            showInDefault="1" showInWebsite="0" showInStore="0" canRestore="1">
                         <label>Varnish fetch tag limit.</label>
-                        <backend_model>IntegerNet\AsyncVarnish\Model\System\Config\Backend\HeaderLength</backend_model>
+                        <backend_model>IntegerNet\AsyncVarnish\Model\System\Config\Backend\FetchTagLimit</backend_model>
                         <comment>The maximum amount of tags that are fetched in 1 purge request. This can be
                             set to a fairly high number (1 million by default), unless you run into resource
                             limits/timeouts.</comment>