JSON fields support

app/etc/di.xml

@@ -1453,6 +1453,7 @@
                 <item name="primary" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Dto\Factories\Primary</item>
                 <item name="foreign" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Dto\Factories\Foreign</item>
                 <item name="index" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Dto\Factories\Index</item>
+                <item name="json" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Dto\Factories\Json</item>
             </argument>
         </arguments>
     </type>
@@ -1480,6 +1481,7 @@
                 <item name="varchar" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Db\MySQL\Definition\Columns\StringBinary</item>
                 <item name="binary" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Db\MySQL\Definition\Columns\StringBinary</item>
                 <item name="varbinary" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Db\MySQL\Definition\Columns\StringBinary</item>
+                <item name="json" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Db\MySQL\Definition\Columns\Json</item>
                 <item name="index" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Db\MySQL\Definition\Index</item>
                 <item name="unique" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Db\MySQL\Definition\Constraints\Internal</item>
                 <item name="primary" xsi:type="object">\Magento\Framework\Setup\Declaration\Schema\Db\MySQL\Definition\Constraints\Internal</item>
@@ -1593,6 +1595,7 @@
                 <item name="datetime" xsi:type="object">Magento\Framework\Setup\SchemaListenerDefinition\TimestampDefinition</item>
                 <item name="date" xsi:type="object">Magento\Framework\Setup\SchemaListenerDefinition\DateDefinition</item>
                 <item name="boolean" xsi:type="object">Magento\Framework\Setup\SchemaListenerDefinition\BooleanDefinition</item>
+                <item name="json" xsi:type="object">Magento\Framework\Setup\SchemaListenerDefinition\JsonDefinition</item>
             </argument>
         </arguments>
     </type>

lib/internal/Magento/Framework/Setup/Declaration/Schema/Db/MySQL/Definition/Columns/Json.php

@@ -0,0 +1,74 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\Framework\Setup\Declaration\Schema\Db\MySQL\Definition\Columns;
+
+use Magento\Framework\App\ResourceConnection;
+use Magento\Framework\Setup\Declaration\Schema\Db\DbDefinitionProcessorInterface;
+use Magento\Framework\Setup\Declaration\Schema\Dto\ElementInterface;
+
+/**
+ * Process json data type.
+ */
+class Json implements DbDefinitionProcessorInterface
+{
+    /**
+     * @var Nullable
+     */
+    private $nullable;
+
+    /**
+     * @var ResourceConnection
+     */
+    private $resourceConnection;
+
+    /**
+     * @var Comment
+     */
+    private $comment;
+
+    /**
+     * Blob constructor.
+     *
+     * @param Nullable $nullable
+     * @param Comment $comment
+     * @param ResourceConnection $resourceConnection
+     */
+    public function __construct(
+        Nullable $nullable,
+        Comment $comment,
+        ResourceConnection $resourceConnection
+    ) {
+        $this->nullable = $nullable;
+        $this->resourceConnection = $resourceConnection;
+        $this->comment = $comment;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function toDefinition(ElementInterface $column)
+    {
+        return sprintf(
+            '%s %s %s %s',
+            $this->resourceConnection->getConnection()->quoteIdentifier($column->getName()),
+            $column->getType(),
+            $this->nullable->toDefinition($column),
+            $this->comment->toDefinition($column)
+        );
+    }
+
+    /**
+     * Returns an array of column definitions
+     *
+     * @param array $data
+     * @return array
+     */
+    public function fromDefinition(array $data)
+    {
+        return $data;
+    }
+}

lib/internal/Magento/Framework/Setup/Declaration/Schema/Dto/Columns/Json.php

@@ -0,0 +1,69 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\Framework\Setup\Declaration\Schema\Dto\Columns;
+
+use Magento\Framework\Setup\Declaration\Schema\Dto\Column;
+use Magento\Framework\Setup\Declaration\Schema\Dto\ElementDiffAwareInterface;
+use Magento\Framework\Setup\Declaration\Schema\Dto\Table;
+
+/**
+ * Json
+ *
+ * Text column.
+ * Declared in SQL, like: JSON
+ */
+class Json extends Column implements ElementDiffAwareInterface, ColumnNullableAwareInterface
+{
+    /**
+     * @var bool
+     */
+    private $nullable;
+
+    /**
+     * Constructor.
+     *
+     * @param string $name
+     * @param string $type
+     * @param Table $table
+     * @param bool $nullable
+     * @param string|null $comment
+     * @param string|null $onCreate
+     */
+    public function __construct(
+        string $name,
+        string $type,
+        Table $table,
+        bool $nullable = true,
+        string $comment = null,
+        string $onCreate = null
+    ) {
+        parent::__construct($name, $type, $table, $comment, $onCreate);
+        $this->nullable = $nullable;
+    }
+
+    /**
+     * Check whether column can be nullable.
+     *
+     * @return bool
+     */
+    public function isNullable()
+    {
+        return $this->nullable;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function getDiffSensitiveParams()
+    {
+        return [
+            'type' => $this->getType(),
+            'nullable' => $this->isNullable(),
+            'comment' => $this->getComment()
+        ];
+    }
+}

lib/internal/Magento/Framework/Setup/Declaration/Schema/Dto/Factories/Json.php

@@ -0,0 +1,50 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\Framework\Setup\Declaration\Schema\Dto\Factories;
+
+use Magento\Framework\ObjectManagerInterface;
+
+/**
+ * Class Json
+ */
+class Json implements FactoryInterface
+{
+    /**
+     * @var ObjectManagerInterface
+     */
+    private $objectManager;
+
+    /**
+     * @var string
+     */
+    private $className;
+
+    /**
+     * Constructor.
+     *
+     * @param ObjectManagerInterface $objectManager
+     * @param string $className
+     */
+    public function __construct(
+        ObjectManagerInterface $objectManager,
+        $className = \Magento\Framework\Setup\Declaration\Schema\Dto\Columns\Blob::class
+    ) {
+        $this->objectManager = $objectManager;
+        $this->className = $className;
+    }
+
+    /**
+     * Create element using definition data array.
+     *
+     * @param array $data
+     * @return \Magento\Framework\Setup\Declaration\Schema\Dto\ElementInterface|mixed
+     */
+    public function create(array $data)
+    {
+        return $this->objectManager->create($this->className, $data);
+    }
+}

lib/internal/Magento/Framework/Setup/Declaration/Schema/etc/schema.xsd

@@ -20,6 +20,7 @@
     <xs:include schemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/types/texts/longtext.xsd" />
     <xs:include schemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/types/texts/mediumtext.xsd" />
     <xs:include schemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/types/texts/varchar.xsd" />
+    <xs:include schemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/types/texts/json.xsd" />
     <xs:include schemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/types/binaries/blob.xsd" />
     <xs:include schemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/types/binaries/mediumblob.xsd" />
     <xs:include schemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/types/binaries/longblob.xsd" />

lib/internal/Magento/Framework/Setup/Declaration/Schema/etc/types/texts/json.xsd

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+-->
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
+    <xs:include schemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/types/column.xsd"/>
+
+    <xs:complexType name="json">
+        <xs:complexContent>
+            <xs:extension base="abstractColumnType">
+                <xs:annotation>
+                    <xs:documentation>
+                        Well formatted Json object
+                    </xs:documentation>
+                </xs:annotation>
+                <xs:attribute name="nullable" type="xs:boolean" />
+            </xs:extension>
+        </xs:complexContent>
+    </xs:complexType>
+</xs:schema>

lib/internal/Magento/Framework/Setup/SchemaListenerDefinition/JsonDefinition.php

@@ -0,0 +1,25 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\Framework\Setup\SchemaListenerDefinition;
+
+/**
+ * Json type definition.
+ */
+class JsonDefinition implements DefinitionConverterInterface
+{
+    /**
+     * @inheritdoc
+     */
+    public function convertToDefinition(array $definition)
+    {
+        return [
+            'xsi:type' => $definition['type'],
+            'name' => $definition['name'],
+            'nullable' => $definition['nullable'] ?? true
+        ];
+    }
+}