I'm trying make a search field in my app. First I want load all results, but if user request the search, show only your answer.

```
def get_queryset(self):
    pista = self.request.GET.get('pesquisar_por')

    sql = (
    "SELECT t1.codigo, t1.nome, t1.quantidade, t1.preco_venda, t2.nome as nome_grupo "+
    "FROM produto t1 "+
    "LEFT JOIN grupo t2 on (t1.grupo = t2.codigo) "+
    "WHERE t1.status= 'A' ")
    if pista is not None:
        sql = sql + ("AND t1.nome LIKE %s", ['%'+pista+'%'])
    sql = sql + "ORDER BY t1.nome LIMIT 300"
    produtos = Produto.objects.using('horus').raw(sql)
    return produtos

```

But this showed this error: **Can't convert 'tuple' object to str implicitly**.

The error is in this line: sql = sql + ("AND t1.nome LIKE %s", ['%'+pista+'%'])