From 4fbd9b4e74bb1c93a8a953f41a3695d25eea8977 Mon Sep 17 00:00:00 2001
From: Takashi Imamichi <imamichi@jp.ibm.com>
Date: Fri, 24 May 2024 15:15:49 +0900
Subject: [PATCH] use mapping-like features of DataBin

---
 qiskit_ibm_runtime/utils/json.py     |  7 +++----
 test/integration/test_sampler_v2.py  |  6 +++---
 test/unit/test_data_serialization.py | 14 +++++---------
 3 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/qiskit_ibm_runtime/utils/json.py b/qiskit_ibm_runtime/utils/json.py
index b2b005a28..cf180d374 100644
--- a/qiskit_ibm_runtime/utils/json.py
+++ b/qiskit_ibm_runtime/utils/json.py
@@ -270,10 +270,9 @@ def default(self, obj: Any) -> Any:  # pylint: disable=arguments-differ
             return {"__type__": "BitArray", "__value__": out_val}
         if isinstance(obj, DataBin):
             out_val = {
-                "field_names": obj._FIELDS,
-                "field_types": [str(field_type) for field_type in obj._FIELD_TYPES],
-                "shape": obj._SHAPE,
-                "fields": {field_name: getattr(obj, field_name) for field_name in obj._FIELDS},
+                "field_names": list(obj),
+                "shape": obj.shape,
+                "fields": dict(obj.items()),
             }
             return {"__type__": "DataBin", "__value__": out_val}
         if isinstance(obj, EstimatorPub):
diff --git a/test/integration/test_sampler_v2.py b/test/integration/test_sampler_v2.py
index 6647fb45b..783b69f41 100644
--- a/test/integration/test_sampler_v2.py
+++ b/test/integration/test_sampler_v2.py
@@ -513,10 +513,10 @@ def test_circuit_with_multiple_cregs(self, service):
                     result = sampler.run([qc]).result()
                     self.assertEqual(len(result), 1)
                     data = result[0].data
-                    self.assertEqual(len(data._FIELDS), 3)
+                    self.assertEqual(len(data), 3)
                     for creg in qc.cregs:
-                        self.assertTrue(hasattr(data, creg.name))
-                        self._assert_allclose(getattr(data, creg.name), np.array(target[creg.name]))
+                        self.assertIn(creg.name, data)
+                        self._assert_allclose(data[creg.name], np.array(target[creg.name]))
 
     @run_integration_test
     def test_samplerv2_options(self, service):
diff --git a/test/unit/test_data_serialization.py b/test/unit/test_data_serialization.py
index e2be4f306..a08bac75e 100644
--- a/test/unit/test_data_serialization.py
+++ b/test/unit/test_data_serialization.py
@@ -296,15 +296,11 @@ def assert_data_bins_equal(self, dbin1, dbin2):
         """Compares two DataBins
         Field types are compared up to their string representation
         """
-        self.assertEqual(dbin1._FIELDS, dbin2._FIELDS)
-        self.assertEqual(
-            [str(field_type) for field_type in dbin1._FIELD_TYPES],
-            [str(field_type) for field_type in dbin2._FIELD_TYPES],
-        )
-        self.assertEqual(dbin1._SHAPE, dbin2._SHAPE)
-        for field_name in dbin1._FIELDS:
-            field_1 = getattr(dbin1, field_name)
-            field_2 = getattr(dbin2, field_name)
+        self.assertEqual(tuple(dbin1), tuple(dbin2))
+        self.assertEqual(dbin1.shape, dbin2.shape)
+        for field_name in dbin1:
+            field_1 = dbin1[field_name]
+            field_2 = dbin2[field_name]
             if isinstance(field_1, np.ndarray):
                 np.testing.assert_allclose(field_1, field_2)
             else: