Use struct for node metadata

tests/test_inference.py

@@ -1094,9 +1094,11 @@ def test_from_standard_tree_sequence(self):
             assert i1.flags == i2.flags
             assert tsutil.json_metadata_is_subset(i1.metadata, i2.metadata)
         # Unless inference is perfect, internal nodes may differ, but sample nodes
-        # should be identical
+        # should be identical. Node metadata is not transferred, however, and a tsinfer-
+        # specific node metadata schema is used (where empty is None rather than b"")
+        assert ts.table_metadata_schemas.node == tsinfer.formats.node_metadata_schema()
         for n1, n2 in zip(ts.samples(), ts_inferred.samples()):
-            assert ts.node(n1) == ts_inferred.node(n2)
+            assert ts.node(n1).replace(metadata=None) == ts_inferred.node(n2)
         # Sites can have metadata added by the inference process, but inferred site
         # metadata should always include all the metadata in the original ts
         for s1, s2 in zip(ts.sites(), ts_inferred.sites()):
@@ -1586,7 +1588,7 @@ def verify(self, sample_data, mismatch_ratio=None, recombination_rate=None):
             ancestors_time = ancestor_data.ancestors_time[:]
             num_ancestor_nodes = 0
             for n in ancestors_ts.nodes():
-                md = json.loads(n.metadata) if n.metadata else {}
+                md = n.metadata if n.metadata else {}
                 if tsinfer.is_pc_ancestor(n.flags):
                     assert not ("ancestor_data_id" in md)
                 else:
@@ -3114,8 +3116,7 @@ def verify_augmented_ancestors(
             node = t2.nodes[m + j]
             assert node.flags == tsinfer.NODE_IS_SAMPLE_ANCESTOR
             assert node.time == 1
-            metadata = json.loads(node.metadata.decode())
-            assert node_id == metadata["sample_data_id"]
+            assert node_id == node.metadata["sample_data_id"]
 
         t2.nodes.truncate(len(t1.nodes))
         # Adding and subtracting 1 can lead to small diffs, so we compare
@@ -3265,8 +3266,7 @@ def verify_example(self, full_subset, samples, ancestors, path_compression):
             num_sample_ancestors = 0
             for node in final_ts.nodes():
                 if node.flags == tsinfer.NODE_IS_SAMPLE_ANCESTOR:
-                    metadata = json.loads(node.metadata.decode())
-                    assert metadata["sample_data_id"] in subset
+                    assert node.metadata["sample_data_id"] in subset
                     num_sample_ancestors += 1
             assert expected_sample_ancestors == num_sample_ancestors
             tsinfer.verify(samples, final_ts.simplify())

tsinfer/formats.py

@@ -74,6 +74,32 @@ def permissive_json_schema():
     }
 
 
+def node_metadata_schema():
+    # This is fixed by tsinfer: users cannot add to the node metadata
+    return tskit.MetadataSchema(
+        {
+            "codec": "struct",
+            "type": ["object", "null"],
+            "properties": {
+                "ancestor_data_id": {
+                    "description": "",
+                    "type": "integer",
+                    "binaryFormat": "i",
+                    "default": -1,
+                },
+                "sample_data_id": {
+                    "description": "Date of sample collection in ISO format",
+                    "type": "integer",
+                    "binaryFormat": "i",
+                    "default": -1,
+                },
+            },
+            "required": ["ancestor_data_id", "sample_data_id"],
+            "additionalProperties": False,
+        }
+    )
+
+
 def np_obj_equal(np_obj_array1, np_obj_array2):
     """
     A replacement for np.array_equal to test equality of numpy arrays that

tsinfer/inference.py

@@ -1411,12 +1411,7 @@ def get_ancestors_tree_sequence(self):
         pc_ancestors = is_pc_ancestor(flags)
         tables.nodes.set_columns(flags=flags, time=times)
 
-        # # FIXME we should do this as a struct codec?
-        # dict_schema = permissive_json_schema()
-        # dict_schema = add_to_schema(dict_schema, "ancestor_data_id",
-        #         {"type": "integer"})
-        # schema = tskit.MetadataSchema(dict_schema)
-        # tables.nodes.schema = schema
+        tables.nodes.metadata_schema = formats.node_metadata_schema()
 
         # Add metadata for any non-PC node, pointing to the original ancestor
         metadata = []
@@ -1425,7 +1420,11 @@ def get_ancestors_tree_sequence(self):
             if is_pc:
                 metadata.append(b"")
             else:
-                metadata.append(_encode_raw_metadata({"ancestor_data_id": ancestor}))
+                metadata.append(
+                    tables.nodes.metadata_schema.validate_and_encode_row(
+                        {"ancestor_data_id": ancestor, "sample_data_id": tskit.NULL}
+                    )
+                )
                 ancestor += 1
         tables.nodes.packset_metadata(metadata)
         left, right, parent, child = tsb.dump_edges()
@@ -1471,6 +1470,7 @@ def store_output(self):
             tables = tskit.TableCollection(
                 sequence_length=self.ancestor_data.sequence_length
             )
+            tables.nodes.metadata_schema = formats.node_metadata_schema()
             ts = tables.tree_sequence()
         return ts
 
@@ -1830,9 +1830,10 @@ def get_augmented_ancestors_tree_sequence(self, sample_indexes):
                 tables.nodes.add_row(
                     flags=constants.NODE_IS_SAMPLE_ANCESTOR,
                     time=times[j],
-                    metadata=_encode_raw_metadata(
-                        {"sample_data_id": int(sample_indexes[s])}
-                    ),
+                    metadata={
+                        "ancestor_data_id": tskit.NULL,
+                        "sample_data_id": int(sample_indexes[s]),
+                    },
                 )
                 s += 1
             else: