fix(python): Fix error message for uninstantiated Enum types (pola-…

…rs#12886)
stinodego · Dec 4, 2023 · d2aea50 · d2aea50
1 parent c1f04d1
commit d2aea50
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Showing 3 changed files with 16 additions and 5 deletions.
diff --git a/py-polars/polars/datatypes/convert.py b/py-polars/polars/datatypes/convert.py
@@ -320,7 +320,7 @@ def REPR_TO_DTYPE(self) -> dict[str, PolarsDataType]:
         def _dtype_str_repr_safe(o: Any) -> PolarsDataType | None:
             try:
                 return _dtype_str_repr(o.base_type()).split("[")[0]
-            except ValueError:
+            except TypeError:
                 return None
 
         return {

diff --git a/py-polars/src/conversion.rs b/py-polars/src/conversion.rs
@@ -453,6 +453,11 @@ impl FromPyObject<'_> for Wrap<DataType> {
                     "Binary" => DataType::Binary,
                     "Boolean" => DataType::Boolean,
                     "Categorical" => DataType::Categorical(None),
+                    "Enum" => {
+                        return Err(PyTypeError::new_err(
+                            "Enum types must be instantiated with a list of categories",
+                        ))
+                    },
                     "Date" => DataType::Date,
                     "Datetime" => DataType::Datetime(TimeUnit::Microseconds, None),
                     "Time" => DataType::Time,
@@ -468,8 +473,8 @@ impl FromPyObject<'_> for Wrap<DataType> {
                     "Null" => DataType::Null,
                     "Unknown" => DataType::Unknown,
                     dt => {
-                        return Err(PyValueError::new_err(format!(
-                            "{dt} is not a recognised polars DataType.",
+                        return Err(PyTypeError::new_err(format!(
+                            "'{dt}' is not a Polars data type",
                         )))
                     },
                 }
@@ -539,8 +544,7 @@ impl FromPyObject<'_> for Wrap<DataType> {
             },
             dt => {
                 return Err(PyTypeError::new_err(format!(
-                    "A {dt} object is not a recognised polars DataType. \
-                    Hint: use the class without instantiating it.",
+                    "'{dt}' is not a Polars data type",
                 )))
             },
         };

diff --git a/py-polars/tests/unit/datatypes/test_enum.py b/py-polars/tests/unit/datatypes/test_enum.py
@@ -126,3 +126,10 @@ def test_extend_to_an_enum() -> None:
     s.extend(s2)
     assert s.len() == 8
     assert s.null_count() == 1
+
+
+def test_series_init_uninstantiated_enum() -> None:
+    with pytest.raises(
+        TypeError, match="Enum types must be instantiated with a list of categories"
+    ):
+        pl.Series(["a", "b", "a"], dtype=pl.Enum)