Fix for Service Serialization (Qiskit-Extensions#796)

* Added warning for saving service class.

* Added tests for experiment data serialization and bug fix

* Serialization of numpy.number in json file

Co-authored-by: Christopher J. Wood <cjwood@us.ibm.com>

qiskit_experiments/database_service/db_experiment_data.py

@@ -1835,8 +1835,6 @@ def __json_encode__(self):
         for att in [
             "_metadata",
             "_source",
-            "_service",
-            "_backend",
             "_id",
             "_parent_id",
             "_type",
@@ -1861,6 +1859,15 @@ def __json_encode__(self):
         # Handle non-serializable objects
         json_value["_jobs"] = self._safe_serialize_jobs()
 
+        # the attribute self._service in charge of the connection and communication with the
+        #  experiment db. It doesn't have meaning in the json format so there is no need to serialize
+        #  it.
+        for att in ["_service", "_backend"]:
+            json_value[att] = None
+            value = getattr(self, att)
+            if value is not None:
+                LOG.info("%s cannot be JSON serialized", str(type(value)))
+
         return json_value
 
     @classmethod

qiskit_experiments/framework/json.py

@@ -456,6 +456,8 @@ def default(self, obj: Any) -> Any:  # pylint: disable=arguments-differ
             return {"__type__": "spmatrix", "__value__": value}
         if isinstance(obj, bytes):
             return _serialize_bytes(obj)
+        if isinstance(obj, np.number):
+            return obj.item()
         if dataclasses.is_dataclass(obj):
             return _serialize_object(obj, settings=dataclasses.asdict(obj))
         if isinstance(obj, uncertainties.UFloat):

test/test_qubit_spectroscopy.py

@@ -160,4 +160,57 @@ def test_experiment_config(self):
     def test_roundtrip_serializable(self):
         """Test round trip JSON serialization"""
         exp = QubitSpectroscopy(1, np.linspace(int(100e6), int(150e6), int(20e6)))
+        # Checking serialization of the experiment
         self.assertRoundTripSerializable(exp, self.json_equiv)
+
+    def test_expdata_serialization(self):
+        """Test experiment data and analysis data JSON serialization"""
+        exp_helper = SpectroscopyHelper(line_width=2e6)
+        backend = MockIQBackend(
+            experiment_helper=exp_helper,
+            iq_cluster_centers=[((-1.0, -1.0), (1.0, 1.0))],
+            iq_cluster_width=[0.2],
+        )
+        backend._configuration.basis_gates = ["x"]
+        backend._configuration.timing_constraints = {"granularity": 16}
+
+        qubit = 1
+        freq01 = backend.defaults().qubit_freq_est[qubit]
+        frequencies = np.linspace(freq01 - 10.0e6, freq01 + 10.0e6, 21)
+        exp = QubitSpectroscopy(qubit, frequencies)
+
+        exp.set_run_options(meas_level=MeasLevel.CLASSIFIED, shots=1024)
+        expdata = exp.run(backend).block_for_results()
+        self.assertExperimentDone(expdata)
+
+        # Checking serialization of the experiment data
+        self.assertRoundTripSerializable(expdata, self.experiment_data_equiv)
+
+        # Checking serialization of the analysis
+        self.assertRoundTripSerializable(expdata.analysis_results(1), self.analysis_result_equiv)
+
+    def test_kerneled_expdata_serialization(self):
+        """Test experiment data and analysis data JSON serialization"""
+        exp_helper = SpectroscopyHelper(line_width=2e6)
+        backend = MockIQBackend(
+            experiment_helper=exp_helper,
+            iq_cluster_centers=[((-1.0, -1.0), (1.0, 1.0))],
+            iq_cluster_width=[0.2],
+        )
+        backend._configuration.basis_gates = ["x"]
+        backend._configuration.timing_constraints = {"granularity": 16}
+
+        qubit = 1
+        freq01 = backend.defaults().qubit_freq_est[qubit]
+        frequencies = np.linspace(freq01 - 10.0e6, freq01 + 10.0e6, 21)
+        exp = QubitSpectroscopy(qubit, frequencies)
+
+        exp.set_run_options(meas_level=MeasLevel.KERNELED, shots=1024)
+        expdata = exp.run(backend).block_for_results()
+        self.assertExperimentDone(expdata)
+
+        # Checking serialization of the experiment data
+        self.assertRoundTripSerializable(expdata, self.experiment_data_equiv)
+
+        # Checking serialization of the analysis
+        self.assertRoundTripSerializable(expdata.analysis_results(1), self.analysis_result_equiv)

test/test_readout_angle.py

@@ -16,6 +16,7 @@
 from test.base import QiskitExperimentsTestCase
 import numpy as np
 
+from qiskit.qobj.utils import MeasLevel
 from qiskit_experiments.library import ReadoutAngle
 from qiskit_experiments.test.mock_iq_backend import MockIQBackend
 
@@ -51,3 +52,21 @@ def test_readout_angle_end2end(self):
         self.assertExperimentDone(expdata)
         res = expdata.analysis_results(0)
         self.assertAlmostEqual(res.value % (2 * np.pi), 15 * np.pi / 8, places=2)
+
+    def test_kerneled_expdata_serialization(self):
+        """Test experiment data and analysis data JSON serialization"""
+        backend = MockIQBackend(
+            MockIQReadoutAngleHelper(), iq_cluster_centers=[((-3.0, 3.0), (5.0, 5.0))]
+        )
+
+        exp = ReadoutAngle(0)
+
+        exp.set_run_options(meas_level=MeasLevel.KERNELED, shots=1024)
+        expdata = exp.run(backend).block_for_results()
+        self.assertExperimentDone(expdata)
+
+        # Checking serialization of the experiment data
+        self.assertRoundTripSerializable(expdata, self.experiment_data_equiv)
+
+        # Checking serialization of the analysis
+        self.assertRoundTripSerializable(expdata.analysis_results(0), self.analysis_result_equiv)

test/test_resonator_spectroscopy.py

@@ -95,3 +95,32 @@ def test_roundtrip_serializable(self):
         """Test round trip JSON serialization"""
         exp = ResonatorSpectroscopy(1, frequencies=np.linspace(int(100e6), int(150e6), int(20e6)))
         self.assertRoundTripSerializable(exp, self.json_equiv)
+
+    @data(-5e6, 0, 3e6)
+    def test_kerneled_expdata_serialization(self, freq_shift):
+        """Test experiment data and analysis data JSON serialization"""
+        qubit = 1
+        backend = MockIQBackend(
+            experiment_helper=ResonatorSpectroscopyHelper(
+                gate_name="measure", freq_offset=freq_shift
+            ),
+            iq_cluster_centers=[((0.0, 0.0), (-1.0, 0.0))],
+            iq_cluster_width=[0.2],
+        )
+        backend._configuration.timing_constraints = {"granularity": 16}
+
+        res_freq = backend.defaults().meas_freq_est[qubit]
+
+        frequencies = np.linspace(res_freq - 20e6, res_freq + 20e6, 51)
+        exp = ResonatorSpectroscopy(qubit, backend=backend, frequencies=frequencies)
+
+        expdata = exp.run(backend).block_for_results()
+        self.assertExperimentDone(expdata)
+
+        # since under _experiment in kwargs there is an argument of the backend which isn't serializable.
+        expdata._experiment = None
+        # Checking serialization of the experiment data
+        self.assertRoundTripSerializable(expdata, self.experiment_data_equiv)
+
+        # Checking serialization of the analysis
+        self.assertRoundTripSerializable(expdata.analysis_results(1), self.analysis_result_equiv)

test/test_t2hahn.py

@@ -166,9 +166,31 @@ def test_experiment_config(self):
 
     def test_roundtrip_serializable(self):
         """Test round trip JSON serialization"""
-        exp = T2Hahn(0, [1, 2, 3, 4, 5])
+
+        delays0 = list(range(1, 60, 2))
+
+        exp = T2Hahn(0, delays0)
         self.assertRoundTripSerializable(exp, self.json_equiv)
 
+        osc_freq = 0.08
+        estimated_t2hahn = 30
+        backend = T2HahnBackend(
+            t2hahn=[estimated_t2hahn],
+            frequency=[osc_freq],
+            initialization_error=[0.0],
+            readout0to1=[0.02],
+            readout1to0=[0.02],
+        )
+        exp.analysis.set_options(p0={"amp": 0.5, "tau": estimated_t2hahn, "base": 0.5}, plot=False)
+        expdata = exp.run(backend=backend, shots=1000).block_for_results()
+        self.assertExperimentDone(expdata)
+
+        # Checking serialization of the experiment data
+        self.assertRoundTripSerializable(expdata, self.experiment_data_equiv)
+
+        # Checking serialization of the analysis
+        self.assertRoundTripSerializable(expdata.analysis_results(1), self.analysis_result_equiv)
+
     def test_analysis_config(self):
         """ "Test converting analysis to and from config works"""
         analysis = T2HahnAnalysis()