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Handle some error conditions

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Simon Willison 2021-08-13 08:33:13 -07:00
commit 62aac6593a
1 changed files with 7 additions and 2 deletions
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9
datasette/utils/__init__.py
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@ -1098,6 +1098,8 @@ def columns_for_query(conn, sql, params=None):
per returned column. ``(None, None)`` if no table and column per returned column. ``(None, None)`` if no table and column
could be derived. could be derived.
""" """
if sql.lower().strip().startswith("explain"):
return []
rows = conn.execute("explain " + sql, params).fetchall() rows = conn.execute("explain " + sql, params).fetchall()
table_rootpage_by_register = { table_rootpage_by_register = {
r["p1"]: r["p2"] for r in rows if r["opcode"] == "OpenRead" r["p1"]: r["p2"] for r in rows if r["opcode"] == "OpenRead"
@ -1113,8 +1115,11 @@ def columns_for_query(conn, sql, params=None):
for row in rows: for row in rows:
if row["opcode"] in ("Rowid", "Column"): if row["opcode"] in ("Rowid", "Column"):
addr, opcode, table_id, cid, column_register, p4, p5, comment = row addr, opcode, table_id, cid, column_register, p4, p5, comment = row
table = names_by_rootpage[table_rootpage_by_register[table_id]] try:
columns_by_column_register[column_register] = (table, cid) table = names_by_rootpage[table_rootpage_by_register[table_id]]
columns_by_column_register[column_register] = (table, cid)
except KeyError:
pass
result_row = [dict(r) for r in rows if r["opcode"] == "ResultRow"][0] result_row = [dict(r) for r in rows if r["opcode"] == "ResultRow"][0]
registers = list(range(result_row["p1"], result_row["p1"] + result_row["p2"])) registers = list(range(result_row["p1"], result_row["p1"] + result_row["p2"]))
all_column_names = {} all_column_names = {}