Write null when there is no parent-snapshot-id (#1383)

Author: Fokko

pyiceberg/manifest.py

@@ -957,7 +957,11 @@ def __init__(self, output_file: OutputFile, snapshot_id: int, parent_snapshot_id
         super().__init__(
             format_version=1,
             output_file=output_file,
-            meta={"snapshot-id": str(snapshot_id), "parent-snapshot-id": str(parent_snapshot_id), "format-version": "1"},
+            meta={
+                "snapshot-id": str(snapshot_id),
+                "parent-snapshot-id": str(parent_snapshot_id) if parent_snapshot_id is not None else "null",
+                "format-version": "1",
+            },
         )
 
     def prepare_manifest(self, manifest_file: ManifestFile) -> ManifestFile:
@@ -976,7 +980,7 @@ def __init__(self, output_file: OutputFile, snapshot_id: int, parent_snapshot_id
             output_file=output_file,
             meta={
                 "snapshot-id": str(snapshot_id),
-                "parent-snapshot-id": str(parent_snapshot_id),
+                "parent-snapshot-id": str(parent_snapshot_id) if parent_snapshot_id is not None else "null",
                 "sequence-number": str(sequence_number),
                 "format-version": "2",
             },

tests/utils/test_manifest.py

@@ -16,7 +16,7 @@
 # under the License.
 # pylint: disable=redefined-outer-name,arguments-renamed,fixme
 from tempfile import TemporaryDirectory
-from typing import Dict
+from typing import Dict, Optional
 from unittest.mock import patch
 
 import fastavro
@@ -526,14 +526,18 @@ def test_write_manifest(
 
 
 @pytest.mark.parametrize("format_version", [1, 2])
+@pytest.mark.parametrize("parent_snapshot_id", [19, None])
 def test_write_manifest_list(
-    generated_manifest_file_file_v1: str, generated_manifest_file_file_v2: str, format_version: TableVersion
+    generated_manifest_file_file_v1: str,
+    generated_manifest_file_file_v2: str,
+    format_version: TableVersion,
+    parent_snapshot_id: Optional[int],
 ) -> None:
     io = load_file_io()
 
     snapshot = Snapshot(
         snapshot_id=25,
-        parent_snapshot_id=19,
+        parent_snapshot_id=parent_snapshot_id,
         timestamp_ms=1602638573590,
         manifest_list=generated_manifest_file_file_v1 if format_version == 1 else generated_manifest_file_file_v2,
         summary=Summary(Operation.APPEND),
@@ -545,12 +549,20 @@ def test_write_manifest_list(
         path = tmp_dir + "/manifest-list.avro"
         output = io.new_output(path)
         with write_manifest_list(
-            format_version=format_version, output_file=output, snapshot_id=25, parent_snapshot_id=19, sequence_number=0
+            format_version=format_version,
+            output_file=output,
+            snapshot_id=25,
+            parent_snapshot_id=parent_snapshot_id,
+            sequence_number=0,
         ) as writer:
             writer.add_manifests(demo_manifest_list)
         new_manifest_list = list(read_manifest_list(io.new_input(path)))
 
-        expected_metadata = {"snapshot-id": "25", "parent-snapshot-id": "19", "format-version": str(format_version)}
+        if parent_snapshot_id:
+            expected_metadata = {"snapshot-id": "25", "parent-snapshot-id": "19", "format-version": str(format_version)}
+        else:
+            expected_metadata = {"snapshot-id": "25", "parent-snapshot-id": "null", "format-version": str(format_version)}
+
         if format_version == 2:
             expected_metadata["sequence-number"] = "0"
         _verify_metadata_with_fastavro(path, expected_metadata)