Extract model validation into a trait

Also use Laravel’s ValidationException rather than our own custom one

src/Core/Support/ValidatesBeforeSave.php

@@ -0,0 +1,143 @@
+<?php namespace Flarum\Core\Support;
+
+use Illuminate\Contracts\Validation\Factory;
+use Illuminate\Contracts\Validation\ValidationException;
+use Illuminate\Validation\Validator;
+
+trait ValidatesBeforeSave
+{
+    /**
+     * The validation factory instance.
+     *
+     * @var Factory
+     */
+    protected static $validator;
+
+    /**
+     * Boot the model.
+     *
+     * @return void
+     */
+    public static function bootValidatesBeforeSave()
+    {
+        // Before the model is saved, validate it. If validation fails, an
+        // exception will be thrown, preventing the model from saving.
+        static::saving(function ($model) {
+            $model->assertValid();
+        });
+    }
+
+    /**
+     * Set the validation factory instance.
+     *
+     * @param Factory $validator
+     */
+    public static function setValidator(Factory $validator)
+    {
+        static::$validator = $validator;
+    }
+
+    /**
+     * Check whether the model is valid in its current state.
+     *
+     * @return boolean
+     */
+    public function valid()
+    {
+        return $this->makeValidator()->passes();
+    }
+
+    /**
+     * Throw an exception if the model is not valid in its current state.
+     *
+     * @return void
+     *
+     * @throws ValidationException
+     */
+    public function assertValid()
+    {
+        $validator = $this->makeValidator();
+
+        if ($validator->fails()) {
+            $this->throwValidationException($validator);
+        }
+    }
+
+    /**
+     * @param Validator $validator
+     * @throws ValidationException
+     */
+    protected function throwValidationException(Validator $validator)
+    {
+        throw new ValidationException($validator);
+    }
+
+    /**
+     * Make a new validator instance for this model.
+     *
+     * @return \Illuminate\Validation\Validator
+     */
+    protected function makeValidator()
+    {
+        $dirty = $this->getDirty();
+
+        $rules = $this->expandUniqueRules(array_only($this->rules, array_keys($dirty)));
+
+        $validator = static::$validator->make($dirty, $rules);
+
+        // TODO: event
+
+        return $validator;
+    }
+
+    /**
+     * Expand 'unique' rules in a set of validation rules into a fuller form
+     * that Laravel's validator can understand.
+     *
+     * @param array $rules
+     * @return array
+     */
+    protected function expandUniqueRules($rules)
+    {
+        foreach ($rules as $attribute => &$ruleset) {
+            if (is_string($ruleset)) {
+                $ruleset = explode('|', $ruleset);
+            }
+
+            foreach ($ruleset as &$rule) {
+                if (strpos($rule, 'unique') === 0) {
+                    $rule = $this->expandUniqueRule($attribute, $rule);
+                }
+            }
+        }
+
+        return $rules;
+    }
+
+    /**
+     * Expand a 'unique' rule into a fuller form that Laravel's validator can
+     * understand, based on this model's properties.
+     *
+     * @param string $attribute
+     * @param string $rule
+     * @return string
+     */
+    protected function expandUniqueRule($attribute, $rule)
+    {
+        $parts = explode(':', $rule);
+        $key = $this->getKey() ?: 'NULL';
+        $rule = 'unique:'.$this->getTable().','.$attribute.','.$key.','.$this->getKeyName();
+
+        if (! empty($parts[1])) {
+            $wheres = explode(',', $parts[1]);
+
+            foreach ($wheres as &$where) {
+                $where .= ','.$this->$where;
+            }
+
+            $rule .= ','.implode(',', $wheres);
+        }
+
+        return $rule;
+    }
+}