framework/validators/UniqueValidator.php
private function applyTableAlias($query, $conditions, $alias = null)
    {
        if ($alias === null) {
            $alias = array_keys($query->getTablesUsedInFrom())[0];
        }
        $prefixedConditions = [];
        foreach ($conditions as $columnName => $columnValue) {
            if (strpos($columnName, '(') === false) {
                $columnName = preg_replace('/^' . preg_quote($alias) . '\.(.*)$/', '$1', $columnName);
                if (strpos($columnName, '[[') === 0) {
                    $prefixedColumn = "{$alias}.{$columnName}";
                } else {
                    $prefixedColumn = "{$alias}.[[{$columnName}]]";
                }
            } else {
                // there is an expression, can't prefix it reliably
                $prefixedColumn = $columnName;
            }

            $prefixedConditions[$prefixedColumn] = $columnValue;
        }

        return $prefixedConditions;
    }
private function applyTableAlias($query, $conditions, $alias = null)
    {
        if ($alias === null) {
            $alias = array_keys($query->getTablesUsedInFrom())[0];
        }
        $prefixedConditions = [];
        foreach ($conditions as $columnName => $columnValue) {
            if (strpos($columnName, '(') === false) {
                $columnName = preg_replace('/^' . preg_quote($alias) . '\.(.*)$/', '$1', $columnName);
                if (strpos($columnName, '[[') === 0) {
                    $prefixedColumn = "{$alias}.{$columnName}";
                } else {
                    $prefixedColumn = "{$alias}.[[{$columnName}]]";
                }
            } else {
                // there is an expression, can't prefix it reliably
                $prefixedColumn = $columnName;
            }

            $prefixedConditions[$prefixedColumn] = $columnValue;
        }

        return $prefixedConditions;
    }
Returns conditions with alias.
@param ActiveQuery $query
@param array $conditions array of condition, keys to be modified
@param null|string $alias set empty string for no apply alias. Set null for apply primary table alias
@return array