BUG/CLN: clean-up get_values logic in objToJSON

pandas/_libs/src/vendored/ujson/python/objToJSON.c

@@ -181,59 +181,56 @@ static TypeContext *createTypeContext(void) {
 }
 
 static PyObject *get_values(PyObject *obj) {
+  PyObject *typ = NULL;
+  PyObject *arr = NULL;
   PyObject *values = NULL;
 
-  if (object_is_index_type(obj) || object_is_series_type(obj)) {
-    // The special cases to worry about are dt64tz and category[dt64tz].
-    //  In both cases we want the UTC-localized datetime64 ndarray,
-    //  without going through and object array of Timestamps.
-    if (PyObject_HasAttrString(obj, "tz")) {
-      PyObject *tz = PyObject_GetAttrString(obj, "tz");
-      if (tz != Py_None) {
-        // Go through object array if we have dt64tz, since tz info will
-        // be lost if values is used directly.
-        Py_DECREF(tz);
-        values = PyObject_CallMethod(obj, "__array__", NULL);
-        return values;
-      }
-      Py_DECREF(tz);
-    }
+  if (!(object_is_index_type(obj) || object_is_series_type(obj))) {
+    PyObject *typeRepr = PyObject_Repr((PyObject *)Py_TYPE(obj));
+    PyErr_Format(PyExc_ValueError, "get_values expected Series/Index, got %R",
+                 typeRepr);
+    Py_DECREF(typeRepr);
+    return NULL;
+  }
+
+  // MultiIndex raises on .array -> go through .values to get numpy array
+  typ = PyObject_GetAttrString(obj, "_typ");
+  if (PyUnicode_Check(typ) &&
+      PyUnicode_CompareWithASCIIString(typ, "multiindex") == 0) {
+    Py_DECREF(typ);
     values = PyObject_GetAttrString(obj, "values");
     if (values == NULL) {
-      // Clear so we can subsequently try another method
-      PyErr_Clear();
-    } else if (PyObject_HasAttrString(values, "_values_for_json")) {
-      // We have gotten an ExtensionArray
-      PyObject *array_values =
-          PyObject_CallMethod(values, "_values_for_json", NULL);
-      Py_DECREF(values);
-      values = array_values;
-    } else if (!PyArray_CheckExact(values)) {
-      // Didn't get a numpy array, so keep trying
-      Py_DECREF(values);
-      values = NULL;
+      PyErr_SetString(PyExc_ValueError,
+                      "Error retrieving .values from MultiIndex object");
+      return NULL;
     }
+    return values;
   }
+  Py_DECREF(typ);
 
-  if (values == NULL) {
-    PyObject *typeRepr = PyObject_Repr((PyObject *)Py_TYPE(obj));
-    PyObject *repr;
-    if (PyObject_HasAttrString(obj, "dtype")) {
-      PyObject *dtype = PyObject_GetAttrString(obj, "dtype");
-      repr = PyObject_Repr(dtype);
-      Py_DECREF(dtype);
-    } else {
-      repr = PyUnicode_FromString("<unknown dtype>");
-    }
+  // For all other cases, call _values_for_json on the underlying array
+  arr = PyObject_GetAttrString(obj, "array");
+  if (arr == NULL) {
+    PyErr_SetString(PyExc_ValueError,
+                    "Error retrieving .array from Index/Series object");
+    return NULL;
+  }
 
-    PyErr_Format(PyExc_ValueError, "%R or %R are not JSON serializable yet",
-                 repr, typeRepr);
-    Py_DECREF(repr);
-    Py_DECREF(typeRepr);
+  values = PyObject_CallMethod(arr, "_values_for_json", NULL);
 
+  if (values == NULL) {
+    Py_DECREF(arr);
+    PyErr_SetString(PyExc_ValueError, "Error calling _values_for_json");
     return NULL;
   }
-
+  if (!PyArray_CheckExact(values)) {
+    PyErr_Format(PyExc_ValueError,
+                 "_values_for_json should return a numpy array");
+    Py_DECREF(values);
+    Py_DECREF(arr);
+    return NULL;
+  }
+  Py_DECREF(arr);
   return values;
 }