Fix issue with parameters in metadata

qiskit/providers/ibmq/utils/json_encoder.py

@@ -23,6 +23,33 @@
 class IQXJsonEncoder(json.JSONEncoder):
     """A json encoder for qobj"""
 
+    def __encode(self, param: Any) -> Any:
+        """
+        Convert dictionary to contain only JSON serializable types. For example,
+        if the key is a Parameter we convert it to a string.
+        """
+        if isinstance(param, dict):
+            param_bind_str = {}
+            for key in param.keys():
+                value = self.__encode(param[key])
+
+                if isinstance(key, (bool, float, int, str)) or key is None:
+                    param_bind_str[key] = value
+                else:
+                    param_bind_str[str(key)] = value
+            return param_bind_str
+        elif isinstance(param, list):
+            return [self.__encode(p) for p in param]
+        else:
+            return param
+
+    def encode(self, o: Any) -> str:
+        """
+        Return a JSON string representation of a Python data structure.
+        """
+        new_o = self.__encode(o)
+        return super().encode(new_o)
+
     def default(self, o: Any) -> Any:
         # Convert numpy arrays:
         if hasattr(o, 'tolist'):

releasenotes/notes/fix-metadata-parameter-ab6fb1ace79215d9.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fix delivered in `#1065 <https://github.com/Qiskit/qiskit-ibmq-provider/pull/1065>`__ for the
+    issue where job kept crashing when ``Parameter`` was passed in circuit metadata.
+

test/ibmq/test_serialization.py

@@ -15,11 +15,13 @@
 from unittest import SkipTest, skipIf
 from typing import Any, Dict, Optional
 
+import json
 import dateutil.parser
 from qiskit.test.reference_circuits import ReferenceCircuits
 from qiskit.test import slow_test
 from qiskit.providers.ibmq import least_busy
-from qiskit import transpile, schedule, QuantumCircuit
+from qiskit import transpile, schedule, assemble
+from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister
 from qiskit.providers.ibmq.utils.json_encoder import IQXJsonEncoder
 from qiskit.circuit import Parameter
 from qiskit.version import VERSION as terra_version
@@ -178,6 +180,43 @@ def test_convert_complex(self):
         self.assertEqual(val[0], 0.2)
         self.assertEqual(val[1], 0.1)
 
+    def test_exception_message(self):
+        """Test executing job with Parameter in methadata."""
+        qr = QuantumRegister(1)
+        cr = ClassicalRegister(1)
+        my_circ_str = 'test_metadata'
+        my_circ = QuantumCircuit(qr, cr, name=my_circ_str, metadata={Parameter('φ'): 0.2})
+        qobj = assemble(my_circ)
+        qobj_dict = qobj.to_dict()
+        json.dumps(qobj_dict, cls=IQXJsonEncoder)
+        # There is no self.assert method because if we cannot pass Parameter as metadata
+        # the last line throw:
+        # "TypeError: keys must be str, int, float, bool or None, not Parameter"
+
+    def test_encode_no_replace(self):
+        """Test encode where there is no invalid key to replace."""
+        test_dir = {
+            't1': 1,
+            None: None,
+            'list': [1, 2, {'ld': 1, 2: 3}]
+        }
+
+        self.assertEqual('{"t1": 1, "null": null, "list": [1, 2, {"ld": 1, "2": 3}]}',
+                         IQXJsonEncoder().encode(test_dir))
+
+    def test_encode_replace(self):
+        """Test encode where there is no invalid key to replace."""
+        test_dir = {
+            't1': 1,
+            None: None,
+            Parameter('a'): 0.2,
+            'list': [1, 2, {'ld': 1, 2: 3, Parameter('alfa'): 0.1}]
+        }
+
+        self.assertEqual(
+            '{"t1": 1, "null": null, "a": 0.2, "list": [1, 2, {"ld": 1, "2": 3, "alfa": 0.1}]}',
+            IQXJsonEncoder().encode(test_dir))
+
 
 def _find_potential_encoded(data: Any, c_key: str, tally: set) -> None:
     """Find data that may be in JSON serialized format.