Add support for 'html' fields.

composer.json

@@ -4,9 +4,12 @@
   "type": "library",
   "require": {
     "php": ">=7.1",
-    "catlabinteractive/requirements": "^1.0.6",
+    "catlabinteractive/requirements": "^1.0.7",
     "ext-mbstring": "*"
   },
+  "suggest": {
+      "ezyang/htmlpurifier": "^4.14"
+  },
   "require-dev": {
     "phpunit/phpunit": "^9.0",
     "catlabinteractive/cursor-pagination" : "^1.0.8"

src/CharonConfig.php

@@ -5,6 +5,10 @@
 use CatLab\Charon\Models\Singleton;
 use CatLab\Charon\Transformers\ArrayTransformer;
 
+// Optional library
+use HTMLPurifier;
+use HTMLPurifier_Config;
+
 /**
  * Class CharonConfig
  * @package CatLab\Charon
@@ -16,11 +20,49 @@ class CharonConfig extends Singleton
      */
     public $defaultArrayTransformer = ArrayTransformer::class;
 
+    /**
+     * @var HTMLPurifier
+     */
+    private $htmlPurifier;
+
+    /**
+     * @var callable
+     */
+    private $htmlPurifierFactory;
+
     /**
      * @return string
      */
     public function getDefaultArrayTransformer()
     {
         return $this->defaultArrayTransformer;
     }
-}
+
+    /**
+     * @param HTMLPurifier $purifier
+     * @return $this
+     */
+    public function setHtmlPurifierFactory(callable $factory)
+    {
+        $this->htmlPurifierFactory = $factory;
+        return $this;
+    }
+
+    /**
+     * @return HTMLPurifier
+     */
+    public function getHtmlPurifier()
+    {
+        if (!isset($this->htmlPurifier)) {
+
+            if (isset($this->htmlPurifierFactory)) {
+                $this->htmlPurifier = call_user_func($this->htmlPurifierFactory);
+            } else {
+                $config = HTMLPurifier_Config::createDefault();
+                $this->htmlPurifier = new HTMLPurifier($config);
+            }
+        }
+
+        return $this->htmlPurifier;
+    }
+}

src/Models/Properties/Base/Field.php

@@ -14,7 +14,9 @@
 use CatLab\Charon\Models\Properties\ResourceField;
 use CatLab\Charon\Models\ResourceDefinition;
 use CatLab\Charon\Transformers\DateTransformer;
+use CatLab\Charon\Transformers\HtmlTransformer;
 use CatLab\Charon\Transformers\ScalarTransformer;
+use CatLab\Charon\Validation\HtmlValidator;
 use CatLab\Requirements\Enums\PropertyType;
 use CatLab\Requirements\Exceptions\PropertyValidationException;
 use CatLab\Requirements\Interfaces\Property;
@@ -489,6 +491,17 @@ public function datetime($transformer = DateTransformer::class)
         return $this;
     }
 
+    /**
+     * @param $transformer
+     * @return $this
+     */
+    public function html($transformer = HtmlTransformer::class)
+    {
+        $this->type = PropertyType::HTML;
+        $this->transformer($transformer);
+        return $this;
+    }
+
     /**
      * @return array
      */

src/Models/Singleton.php

@@ -15,7 +15,7 @@ protected function __construct()
     }
 
     /**
-     * @return mixed
+     * @return static
      */
     final public static function instance()
     {

src/Transformers/HtmlTransformer.php

@@ -0,0 +1,51 @@
+<?php
+
+namespace CatLab\Charon\Transformers;
+
+use CatLab\Charon\CharonConfig;
+use CatLab\Charon\Exceptions\NotImplementedException;
+use CatLab\Charon\Interfaces\Context;
+use CatLab\Charon\Interfaces\Transformer;
+
+/**
+ *
+ */
+class HtmlTransformer implements Transformer
+{
+    /**
+     * @param $value
+     * @param Context $context
+     * @return mixed|void
+     */
+    public function toResourceValue($value, Context $context)
+    {
+        return $value;
+    }
+
+    /**
+     * @param $value
+     * @param Context $context
+     * @return mixed|void
+     */
+    public function toEntityValue($value, Context $context)
+    {
+        // Is this plain text input?
+        if (strip_tags($value) === $value) {
+            // Wrap around a paragraph
+            $value = '<p>' . nl2br($value) . '</p>';
+        }
+
+        $purifier = CharonConfig::instance()->getHtmlPurifier();
+        return $purifier->purify($value);
+    }
+
+    /**
+     * @param $value
+     * @return mixed|void
+     * @throws \CatLab\Charon\Exceptions\CharonException
+     */
+    public function toParameterValue($value)
+    {
+        throw NotImplementedException::makeTranslatable('HTML parameters are not supported');
+    }
+}

src/Transformers/ScalarTransformer.php

@@ -121,6 +121,7 @@ protected function castToScalar($value)
                 return floatval($value);
 
             case PropertyType::STRING:
+            case PropertyType::HTML:
                 return strval($value);
 
             default: