Fix issue with string types in files.get_elems()

Author: avalentino

src/epr/_epr.pyx

@@ -758,18 +758,23 @@ cdef class Field(EprObject):
                 pyepr_null_ptr_error(msg)
         elif etype == e_tid_string:
             if shape[0] != 1:
-                raise ValueError(f"unexpected number of elements: {shape[0]}")
-            ndim = 0
-            dtype = np.NPY_STRING
-            buf = <char*>epr_get_field_elem_as_str(self._ptr)
-            if buf is NULL:
-                pyepr_null_ptr_error(msg)
+                raise ValueError(
+                    f"unexpected number of elements: {shape[0]} "
+                    "for e_tid_string"
+                )
+            elem = self.get_elem()
+            return np.asarray(elem)
+            # ndim = 0
+            # dtype = np.NPY_STRING
+            # buf = <char*>epr_get_field_elem_as_str(self._ptr)
+            # if buf is NULL:
+            #     pyepr_null_ptr_error(msg)
         # elif etype == e_tid_unknown:
         #     pass
         # elif etype = e_tid_spare:
         #     pass
         else:
-            raise ValueError("invalid field type")
+            raise ValueError(f"invalid field type: {etype}")
 
         out = np.PyArray_SimpleNewFromData(ndim, shape, dtype, <void*>buf)
         # np.PyArray_CLEARFLAG(out, NPY_ARRAY_WRITEABLE)  # new in numpy 1.7

tests/test_all.py

@@ -2134,6 +2134,38 @@ def test_tot_size(self):
         self.assertEqual(self.field.tot_size, tot_size)
 
 
+class TestFieldGetElems(unittest.TestCase):
+    def setUp(self):
+        self.product = epr.Product(PRODUCT_FILE)
+        self.record = self.product.get_sph()
+
+    def test_string_get_elem_int(self):
+        field = self.record.get_field("LINE_LENGTH")
+        value = field.get_elem()
+        self.assertIsInstance(value, int)
+        self.assertEqual(value, 1452)
+
+    def test_string_get_elem_str(self):
+        field = self.record.get_field("SPH_DESCRIPTOR")
+        value = field.get_elem()
+        self.assertIsInstance(value, bytes)
+        self.assertEqual(value, b"AP Mode Medium Res. Image")
+
+    def test_string_get_elems_int(self):
+        field = self.record.get_field("LINE_LENGTH")
+        value = field.get_elems()
+        self.assertIsInstance(value, np.ndarray)
+        self.assertTrue(np.isdtype(value.dtype, "integral"))
+        self.assertEqual(value.item(), 1452)
+
+    def test_string_get_elems_str(self):
+        field = self.record.get_field("SPH_DESCRIPTOR")
+        value = field.get_elems()
+        self.assertIsInstance(value, np.ndarray)
+        self.assertFalse(np.isdtype(value.dtype, "numeric"))
+        self.assertEqual(value.item(), b"AP Mode Medium Res. Image")
+
+
 class TestFieldRW(TestField):
     OPEN_MODE = "rb+"