“Row is not JSON serializable” error when sending result set to a Flask view

results = crsr.execute(query).fetchall()
print(f"{type(results)} of type {type(results[0])}")
#  of type 

json_string = json.dumps(results)
# TypeError: Object of type Row is not JSON serializable

results = [tuple(row) for row in results]
print(f"{type(results)} of type {type(results[0])}")
#  of type 

json_string = json.dumps(results)
# no error (unless the tuples themselves contain elements that are not serializable)

json_string = json.dumps(results, default=str)

query = "SELECT CAST(x AS FLOAT) AS x FROM tbl"

query = "SELECT x FROM tbl"