Return CSV errors as plain text, closes #2129

datasette/handle_exception.py

@@ -59,6 +59,10 @@ def handle_exception(datasette, request, exception):
             body = dict(info)
             body.update(error_body(plain_message or message, status))
             return Response.json(body, status=status, headers=headers)
+        if request.path.split("?")[0].endswith(".csv"):
+            return Response.text(
+                plain_message or message, status=status, headers=headers
+            )
         info.update(
             {
                 "ok": False,

datasette/views/base.py

@@ -35,7 +35,7 @@ class DatasetteError(Exception):
         self.error_dict = error_dict or {}
         self.status = status
         self.message_is_html = message_is_html
-        # Plain text used for JSON error responses when message is HTML
+        # Plain text used for JSON and CSV error responses when message is HTML
         self.plain_message = plain_message
 
 

docs/changelog.rst

@@ -26,6 +26,7 @@ Datasette plugins can now use **background tasks** to run code independent of th
 Bug fixes
 ~~~~~~~~~
 
+- CSV endpoints now return plain-text error messages for SQL errors. (:issue:`2129`)
 - The :ref:`render_cell() <plugin_hook_render_cell>` plugin hook now receives an empty ``pks`` list when rendering SQL views in HTML, matching the JSON ``?_extra=render_cell`` behavior. (:issue:`2639`)
 - Numeric comparison filters now correctly handle decimal values, negative numbers and scientific notation when filtering computed columns and SQL views. Thanks, `Rami Abdelrazzaq <https://github.com/RamiNoodle733>`__. (:issue:`1681`, :pr:`2876`)
 - Fixed CSV streaming with ``?_stream=on`` on SQL views repeating the second page of results until the CSV size limit was reached. Thanks, `Ankita Advitot <https://github.com/AnkitaAdvitot>`__. (:issue:`2902`, :pr:`2903`)

tests/test_csv.py

@@ -166,6 +166,66 @@ async def test_custom_sql_csv(ds_client):
     assert response.text == EXPECTED_CUSTOM_CSV
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize("download", (False, True))
+@pytest.mark.parametrize(
+    "query_string,expected_error",
+    (
+        ("sql=select+blah", "no such column: blah"),
+        ("sql=select+*+from+missing", "no such table: missing"),
+        ("sql=select+from", 'near "from": syntax error'),
+        (
+            "sql=delete+from+simple_primary_key",
+            "Statement must be a SELECT",
+        ),
+        ("", "?sql= is required"),
+        (
+            "sql=select+sleep(0.01)&_timelimit=5",
+            (
+                "SQL query took too long. The time limit is"
+                " controlled by the sql_time_limit_ms setting."
+            ),
+        ),
+    ),
+)
+async def test_custom_sql_csv_errors(ds_client, query_string, expected_error, download):
+    if download:
+        query_string += "&_dl=1"
+    response = await ds_client.get(f"/fixtures/-/query.csv?{query_string}")
+    assert response.status_code == 400
+    assert response.headers["content-type"] == "text/plain; charset=utf-8"
+    assert "content-disposition" not in response.headers
+    assert response.text == expected_error
+
+
+@pytest.mark.asyncio
+async def test_custom_sql_csv_error_head(ds_client):
+    response = await ds_client.head("/fixtures/-/query.csv?sql=select+blah")
+    assert response.status_code == 400
+    assert response.headers["content-type"] == "text/plain; charset=utf-8"
+    assert response.content == b""
+
+
+@pytest.mark.asyncio
+async def test_custom_sql_csv_error_cors():
+    ds = Datasette(cors=True)
+    response = await ds.client.get("/_memory/-/query.csv?sql=select+blah")
+    assert response.status_code == 400
+    assert response.headers["content-type"] == "text/plain; charset=utf-8"
+    assert response.headers["access-control-allow-origin"] == "*"
+    assert response.text == "no such column: blah"
+
+
+@pytest.mark.asyncio
+async def test_table_csv_error(ds_client):
+    response = await ds_client.get(
+        "/fixtures/simple_primary_key.csv?_where=blah&_stream=1"
+    )
+    assert response.status_code == 400
+    assert response.headers["content-type"] == "text/plain; charset=utf-8"
+    assert response.text == "no such column: blah"
+
+
 @pytest.mark.asyncio
 async def test_table_csv_download(ds_client):
     response = await ds_client.get("/fixtures/simple_primary_key.csv?_dl=1")