N°6414 Move existing AbstractSimpleField::Validate impl to custom validators

- LinkedSetField
- SelectObjectField
- MultipleChoicesField (warning this hierarchy contains non multiple value fields like SelectField !)

Also change AbstractValidator::Validate signature : now we are returning an array of error messages, so that we can return multiple ones

sources/Form/Helper/FieldHelper.php

@@ -0,0 +1,36 @@
+<?php
+/*
+ * @copyright   Copyright (C) 2010-2023 Combodo SARL
+ * @license     http://opensource.org/licenses/AGPL-3.0
+ */
+
+namespace Combodo\iTop\Form\Helper;
+
+use BinaryExpression;
+use DBObjectSet;
+use DBSearch;
+use FieldExpression;
+use ScalarExpression;
+
+/**
+ * Utility methods for {@see \Combodo\iTop\Form\Field\Field} classes
+ *
+ * @since 3.1.0 N°6414
+ */
+class FieldHelper {
+	/**
+	 * @since 3.1.0 N°6414 Method creation to factorize between uses in {@see \Combodo\iTop\Form\Field\Field} and {@see \Combodo\iTop\Form\Validator\SelectObjectValidator}
+	 */
+	public static function GetObjectsSetFromSearchAndCurrentValueId(DBSearch $oSearch, string $sCurrentValueId) {
+		$oSearchForExistingCurrentValue = $oSearch->DeepClone();
+		$oCheckIdAgainstCurrentValueExpression = new BinaryExpression(
+			new FieldExpression('id', $oSearchForExistingCurrentValue->GetClassAlias()),
+			'=',
+			new ScalarExpression($sCurrentValueId)
+		);
+		$oSearchForExistingCurrentValue->AddConditionExpression($oCheckIdAgainstCurrentValueExpression);
+
+		return new DBObjectSet($oSearchForExistingCurrentValue);
+	}
+
+}