Construct the ``Search`` object.

def build_search(self):
        """
        Construct the ``Search`` object.
        """
        s = self.search()
        s = self.query(s, self._query)
        s = self.filter(s)
        if self.fields:
            s = self.highlight(s)
        s = self.sort(s)
        self.aggregate(s)
        return s