Add metadata attribute to DataSetDefinition

docs/changes/newsfragments/6643.improved

@@ -0,0 +1 @@
+Improves the DataSetDefinition class to allow users to specify metadata to be added to the resulting dataset

src/qcodes/dataset/measurement_extensions.py

@@ -37,6 +37,9 @@ class DataSetDefinition:
     experiment: Experiment | None = None
     """An optional argument specifying which Experiment this dataset should be
     written to"""
+    metadata: dict[str, Any] | None = None
+    """An optional dictionary of metadata that will be added to the dataset
+    generated by this definition"""
 
 
 def setup_measurement_instances(
@@ -107,6 +110,11 @@ def datasaver_builder(
             stack.enter_context(measurement.run(parent_span=datasaver_builder_span))
             for measurement in measurement_instances
         ]
+        for i, datasaver in enumerate(datasavers):
+            ds_def = dataset_definitions[i]
+            if ds_def.metadata is not None:
+                for key, value in ds_def.metadata.items():
+                    datasaver.dataset.add_metadata(tag=key, metadata=value)
         yield datasavers
 
 

tests/dataset/test_measurement_extensions.py

@@ -98,8 +98,17 @@ def default_database_and_experiment_(tmp_path):
 def test_context(default_params, default_database_and_experiment):
     _ = default_database_and_experiment
     set1, set2, set3, meas1, meas2, meas3 = default_params
+    metadata_dict = {  # Nesting dictionaries does NOT work here
+        "test_metadata": "test_meta_value_1",
+        "test_metadata_2": "test_meta_value_2",
+    }
     dataset_definition = [
-        DataSetDefinition(name="dataset_1", independent=[set1], dependent=[meas1]),
+        DataSetDefinition(
+            name="dataset_1",
+            independent=[set1],
+            dependent=[meas1],
+            metadata=metadata_dict,
+        ),
         DataSetDefinition(
             name="dataset_2", independent=[set1, set2, set3], dependent=[meas2, meas3]
         ),
@@ -133,6 +142,8 @@ def test_context(default_params, default_database_and_experiment):
         },
         data_vars=(meas1.name,),
     )
+    assert datasets[0].metadata == metadata_dict
+
     assert_dataset_as_expected(
         datasets[1],
         dims_dict={
@@ -142,6 +153,7 @@ def test_context(default_params, default_database_and_experiment):
         },
         data_vars=(meas2.name, meas3.name),
     )
+    assert datasets[1].metadata == {}
 
 
 def test_dond_into(default_params, default_database_and_experiment):