Plot error message

testcase

Fix

Fix

Fix

test fix

test fix

test fix

changelog

usageexception

test

test

error

error

error

error

error

changed to runtimeerror

CHANGELOG.md

@@ -10,6 +10,7 @@
 * [Fix] Updates errors so only the error message is displayed (and traceback is hidden) ([#407](https://github.com/ploomber/jupysql/issues/407))
 * [Fix] Fixes `%sqlcmd plot` when `--table` or `--column` have spaces ([#409](https://github.com/ploomber/jupysql/issues/409))
 * [Doc] Add QuestDB tutorial ([#350](https://github.com/ploomber/jupysql/issues/350))
+* [Feature] Better error messages when function used in plotting API unsupported by DB driver (#441)
 
 ## 0.7.1 (2023-04-19)
 
@@ -283,4 +284,4 @@ Converted from an IPython Plugin to an Extension for 1.0 compatibility
 
 *Release date: 21-Mar-2013*
 
-* Initial release
+* Initial release

src/sql/plot.py

@@ -6,6 +6,8 @@
 from jinja2 import Template
 
 from sql.util import flatten
+from sqlalchemy.exc import ProgrammingError
+from sql import exceptions
 
 try:
     import matplotlib.pyplot as plt
@@ -25,7 +27,7 @@
 from sql import util
 
 
-def _summary_stats(conn, table, column, with_=None):
+def _summary_stats(conn, table, column, with_=None, driver=None):
     """Compute percentiles and mean for boxplot"""
 
     if not conn:
@@ -44,7 +46,14 @@ def _summary_stats(conn, table, column, with_=None):
 
     query = template.render(table=table, column=column)
 
-    values = conn.execute(query, with_).fetchone()
+    try:
+        values = conn.execute(query, with_).fetchone()
+    except ProgrammingError as e:
+        print(e)
+        raise exceptions.RuntimeError(
+            f"\nEnsure that percentile_disc " f"function is available on {driver}."
+        )
+
     keys = ["q1", "med", "q3", "mean", "N"]
     return {k: float(v) for k, v in zip(keys, flatten(values))}
 
@@ -124,7 +133,9 @@ def _between(conn, table, column, whislo, whishi, with_=None):
 
 # https://github.com/matplotlib/matplotlib/blob/b5ac96a8980fdb9e59c9fb649e0714d776e26701/lib/matplotlib/cbook/__init__.py
 @modify_exceptions
-def _boxplot_stats(conn, table, column, whis=1.5, autorange=False, with_=None):
+def _boxplot_stats(
+    conn, table, column, whis=1.5, autorange=False, with_=None, driver=None
+):
     """Compute statistics required to create a boxplot"""
     if not conn:
         conn = sql.connection.Connection.current
@@ -141,7 +152,8 @@ def _compute_conf_interval(N, med, iqr):
     stats = dict()
 
     # arithmetic mean
-    s_stats = _summary_stats(conn, table, column, with_=with_)
+
+    s_stats = _summary_stats(conn, table, column, with_=with_, driver=driver)
 
     stats["mean"] = s_stats["mean"]
     q1, med, q3 = s_stats["q1"], s_stats["med"], s_stats["q3"]
@@ -250,20 +262,25 @@ def boxplot(payload, table, column, *, orient="v", with_=None, conn=None, ax=Non
 
     payload["connection_info"] = conn._get_curr_sqlalchemy_connection_info()
 
+    driver = payload["connection_info"]["driver"]
+
     ax = plt.gca()
     vert = orient == "v"
 
     set_ticklabels = ax.set_xticklabels if vert else ax.set_yticklabels
     set_label = ax.set_ylabel if vert else ax.set_xlabel
 
     if isinstance(column, str):
-        stats = [_boxplot_stats(conn, table, column, with_=with_)]
+        stats = [_boxplot_stats(conn, table, column, with_=with_, driver=driver)]
         ax.bxp(stats, vert=vert)
         ax.set_title(f"{column!r} from {table!r}")
         set_label(column)
         set_ticklabels([column])
     else:
-        stats = [_boxplot_stats(conn, table, col, with_=with_) for col in column]
+        stats = [
+            _boxplot_stats(conn, table, col, with_=with_, driver=driver)
+            for col in column
+        ]
         ax.bxp(stats, vert=vert)
         ax.set_title(f"Boxplot from {table!r}")
         set_ticklabels(column)

src/tests/integration/test_mssql.py

@@ -112,3 +112,16 @@ def test_sqlplot_boxplot(ip_with_MSSQL, cell):
     out = ip_with_MSSQL.run_cell(cell)
 
     assert type(out.result).__name__ in {"Axes", "AxesSubplot"}
+
+
+def test_unsupported_function(ip_with_MSSQL, test_table_name_dict):
+    # clean current Axes
+    plt.cla()
+    out = ip_with_MSSQL.run_cell(
+        f"%sqlplot boxplot --table " f"{test_table_name_dict['taxi']} --column x"
+    )
+    assert "Ensure that percentile_disc function is available" in str(out.error_in_exec)
+    assert (
+        "If you need help solving this issue, "
+        "send us a message: https://ploomber.io/community" in str(out.error_in_exec)
+    )