feat(ux): improve error message when column is not found

Author: krzysztof-kwitt

ibis/backends/tests/test_generic.py

@@ -345,7 +345,9 @@ def test_select_filter_mutate(backend, alltypes, df):
 
 
 def test_table_fillna_invalid(alltypes):
-    with pytest.raises(com.IbisTypeError, match=r"'invalid_col' is not a field in.*"):
+    with pytest.raises(
+        com.IbisTypeError, match=r"Column 'invalid_col' is not found in table"
+    ):
         alltypes.fillna({'invalid_col': 0.0})
 
     with pytest.raises(
@@ -412,7 +414,9 @@ def test_mutate_rename(alltypes):
 
 
 def test_dropna_invalid(alltypes):
-    with pytest.raises(com.IbisTypeError, match=r"'invalid_col' is not a field in.*"):
+    with pytest.raises(
+        com.IbisTypeError, match=r"Column 'invalid_col' is not found in table"
+    ):
         alltypes.dropna(subset=['invalid_col'])
 
     with pytest.raises(ValueError, match=r".*is not in.*"):

ibis/expr/operations/generic.py

@@ -35,7 +35,11 @@ def __init__(self, table, name):
             name = table.schema.name_at_position(name)
 
         if name not in table.schema:
-            raise com.IbisTypeError(f"value {name!r} is not a field in {table.schema}")
+            columns_formatted = ', '.join(map(repr, table.schema.names))
+            raise com.IbisTypeError(
+                f"Column {name!r} is not found in table. "
+                f"Existing columns: {columns_formatted}."
+            )
 
         super().__init__(table=table, name=name)
 

ibis/expr/types/relations.py

@@ -956,12 +956,14 @@ def fillna(
 
         if isinstance(replacements, collections.abc.Mapping):
             for col, val in replacements.items():
-                try:
-                    col_type = schema[col]
-                except KeyError:
+                if col not in schema:
+                    columns_formatted = ', '.join(map(repr, schema.names))
                     raise com.IbisTypeError(
-                        f'{col!r} is not a field in {schema}.'
+                        f"Column {col!r} is not found in table. "
+                        f"Existing columns: {columns_formatted}."
                     ) from None
+
+                col_type = schema[col]
                 val_type = val.type() if isinstance(val, Expr) else dt.infer(val)
                 if not dt.castable(val_type, col_type):
                     raise com.IbisTypeError(