improve error when calling sqlcmd (#804)

CHANGELOG.md

@@ -14,6 +14,7 @@
 * [Fix] Current connection and switching connections message only displayed when `feedback>=1`
 * [Fix] `--persist/--persist-replace` perform `ROLLBACK` automatically when needed
 * [Fix] `ResultSet` footer (when `displaylimit` truncates results and when showing how to convert to a data frame) now appears in the `ResultSet` plain text representation (#682)
+* [Fix] Improve error when calling `%sqlcmd` (#761)
 * [API Change] When loading connections from a `.ini` file via `%sql --section section_name`, the section name is set as the connection alias
 * [API Change] Starting connections from a `.ini` file via `%sql [section_name]` has been deprecated
 * [Doc] Fixes documentation inaccuracy that said `:variable` was deprecated (we brought it back in `0.9.0`)

src/sql/magic_cmd.py

@@ -11,6 +11,7 @@ from sql.cmd.test import test
 from sql.cmd.profile import profile
 from sql.cmd.explore import explore
 from sql.cmd.snippets import snippets
+from sql.connection import ConnectionManager
 
 try:
     from traitlets.config.configurable import Configurable
@@ -51,6 +52,14 @@ class SqlCmdMagic(Magics, Configurable):
             "explore",
             "snippets",
         ]
+        COMMANDS_CONNECTION_REQUIRED = [
+            "tables",
+            "columns",
+            "test",
+            "profile",
+            "explore",
+        ]
+        COMMANDS_SQLALCHEMY_ONLY = ["tables", "columns", "test", "explore"]
 
         VALID_COMMANDS_MSG = (
             f"Missing argument for %sqlcmd. "
@@ -64,8 +73,19 @@ class SqlCmdMagic(Magics, Configurable):
             command, others = split[0].strip(), split[1:]
 
             if command in AVAILABLE_SQLCMD_COMMANDS:
-                if command not in ["profile"]:
-                    util.support_only_sql_alchemy_connection("%sqlcmd")
+                if (
+                    command in COMMANDS_CONNECTION_REQUIRED
+                    and not ConnectionManager.current
+                ):
+                    raise exceptions.RuntimeError(
+                        f"Cannot execute %sqlcmd {command} because there "
+                        "is no active connection. Connect to a database "
+                        "and try again."
+                    )
+
+                if command in COMMANDS_SQLALCHEMY_ONLY:
+                    util.support_only_sql_alchemy_connection(f"%sqlcmd {command}")
+
                 return self.execute(command, others)
             else:
                 raise exceptions.UsageError(

src/tests/integration/test_questDB.py

@@ -615,17 +615,17 @@ NOT_SUPPORTED_SUFFIX = (
 
 
 @pytest.mark.parametrize(
-    "query",
+    "query, command",
     [
-        ("%sqlcmd tables"),
-        ("%sqlcmd tables --schema some_schema"),
-        ("%sqlcmd columns --table penguins.csv"),
-        ("%sqlcmd test"),
-        ("%sqlcmd test --table penguins.csv"),
+        ("%sqlcmd tables", "tables"),
+        ("%sqlcmd tables --schema some_schema", "tables"),
+        ("%sqlcmd columns --table penguins.csv", "columns"),
+        ("%sqlcmd test", "test"),
+        ("%sqlcmd test --table penguins.csv", "test"),
     ],
 )
-def test_sqlcmd_not_supported_error(ip_questdb, query, capsys):
-    expected_error_message = f"%sqlcmd {NOT_SUPPORTED_SUFFIX}"
+def test_sqlcmd_not_supported_error(ip_questdb, query, command, capsys):
+    expected_error_message = f"%sqlcmd {command} {NOT_SUPPORTED_SUFFIX}"
 
     with pytest.raises(UsageError) as excinfo:
         ip_questdb.run_cell(query)

src/tests/test_magic_cmd.py

@@ -125,6 +125,60 @@ def test_error(tmp_empty, ip, cell, error_message):
     assert str(excinfo.value) == error_message
 
 
+@pytest.mark.parametrize(
+    "command",
+    [
+        "tables",
+        "columns",
+        "test",
+        "profile",
+        "explore",
+    ],
+)
+def test_sqlcmd_error_when_no_connection(ip_empty, command):
+    with pytest.raises(UsageError) as excinfo:
+        ip_empty.run_cell(f"%sqlcmd {command}")
+
+    assert excinfo.value.error_type == "RuntimeError"
+    assert str(excinfo.value) == (
+        f"Cannot execute %sqlcmd {command} because there is no "
+        "active connection. Connect to a database and try again."
+    )
+
+
+def test_sqlcmd_snippets_when_no_connection(ip_empty, capsys):
+    for key in list(store):
+        del store[key]
+
+    ip_empty.run_cell("%sqlcmd snippets")
+    captured = capsys.readouterr()
+    assert "No snippets stored" in captured.out
+
+
+@pytest.mark.parametrize(
+    "query, command",
+    [
+        ("%sqlcmd tables", "tables"),
+        ("%sqlcmd columns --table penguins.csv", "columns"),
+        (
+            "%sqlcmd test --table penguins.csv  --column body_mass_g --greater 2900",
+            "test",
+        ),
+        ("%sqlcmd explore --table penguins.csv", "explore"),
+    ],
+)
+def test_sqlcmd_not_supported_error(ip_with_connections, query, command, capsys):
+    ip_with_connections.run_cell("%sql duckdb_dbapi")
+    expected_error_message = (
+        f"%sqlcmd {command} is only supported with SQLAlchemy connections, "
+        "not with DBAPI connections"
+    )
+    with pytest.raises(UsageError) as excinfo:
+        ip_with_connections.run_cell(query)
+
+    assert expected_error_message in str(excinfo.value)
+
+
 def test_tables(ip):
     out = ip.run_cell("%sqlcmd tables").result._repr_html_()
     assert "author" in out