framework/db/BaseActiveRecord.php
public function getAttributeHint($attribute)
    {
        $hints = $this->attributeHints();
        if (isset($hints[$attribute])) {
            return $hints[$attribute];
        } elseif (strpos($attribute, '.')) {
            $attributeParts = explode('.', $attribute);
            $neededAttribute = array_pop($attributeParts);

            $relatedModel = $this;
            foreach ($attributeParts as $relationName) {
                if ($relatedModel->isRelationPopulated($relationName) && $relatedModel->$relationName instanceof self) {
                    $relatedModel = $relatedModel->$relationName;
                } else {
                    try {
                        $relation = $relatedModel->getRelation($relationName);
                    } catch (InvalidParamException $e) {
                        return '';
                    }
                    /* @var $modelClass ActiveRecordInterface */
                    $modelClass = $relation->modelClass;
                    $relatedModel = $modelClass::instance();
                }
            }

            $hints = $relatedModel->attributeHints();
            if (isset($hints[$neededAttribute])) {
                return $hints[$neededAttribute];
            }
        }

        return '';
    }
public function getAttributeHint($attribute)
    {
        $hints = $this->attributeHints();
        if (isset($hints[$attribute])) {
            return $hints[$attribute];
        } elseif (strpos($attribute, '.')) {
            $attributeParts = explode('.', $attribute);
            $neededAttribute = array_pop($attributeParts);

            $relatedModel = $this;
            foreach ($attributeParts as $relationName) {
                if ($relatedModel->isRelationPopulated($relationName) && $relatedModel->$relationName instanceof self) {
                    $relatedModel = $relatedModel->$relationName;
                } else {
                    try {
                        $relation = $relatedModel->getRelation($relationName);
                    } catch (InvalidParamException $e) {
                        return '';
                    }
                    /* @var $modelClass ActiveRecordInterface */
                    $modelClass = $relation->modelClass;
                    $relatedModel = $modelClass::instance();
                }
            }

            $hints = $relatedModel->attributeHints();
            if (isset($hints[$neededAttribute])) {
                return $hints[$neededAttribute];
            }
        }

        return '';
    }
Returns the text hint for the specified attribute.
If the attribute looks like `relatedModel.attribute`, then the attribute will be received from the related model.
@param string $attribute the attribute name
@return string the attribute hint
@see attributeHints()
@since 2.0.4