Fix for concat changes when one diff is there (not possbile to concat)

server/mergin/sync/models.py

@@ -37,7 +37,7 @@
     PushChangeType,
 )
 from .interfaces import WorkspaceRole
-from .storages.disk import move_to_tmp
+from .storages.disk import copy_file, move_to_tmp
 from ..app import db
 from .storages import DiskStorage
 from .utils import (
@@ -1021,8 +1021,14 @@ def construct_checkpoint(self) -> bool:
 
         project: Project = basefile.file.project
         os.makedirs(project.storage.diffs_dir, exist_ok=True)
+
         try:
-            project.storage.geodiff.concat_changes(diffs_paths, self.abs_path)
+            if len(diffs_paths) == 1:
+                # if there is only one diff, we can just copy it as a checkpoint without merging
+                # geodiff.concat_changes is not able to concat one diff
+                copy_file(diffs_paths[0], self.abs_path)
+            else:
+                project.storage.geodiff.concat_changes(diffs_paths, self.abs_path)
         except (GeoDiffLibError, GeoDiffLibConflictError):
             logging.error(
                 f"Geodiff: Failed to merge diffs for file {self.file_path_id}"

server/mergin/tests/test_public_api_v2.py

@@ -261,7 +261,7 @@ def test_create_diff_checkpoint(diff_project):
     shutil.copy(
         os.path.join(diff_project.storage.project_dir, "v9", "test.gpkg"), base_gpkg
     )
-    for i in range(22):
+    for i in range(23):
         sql = f"UPDATE simple SET rating={i}"
         execute_query(base_gpkg, sql)
         pv = push_change(
@@ -348,6 +348,24 @@ def test_create_diff_checkpoint(diff_project):
         assert mock.called
         assert not os.path.exists(diff.abs_path)
 
+    # testing checkpoint with one diff only, no merging should happen, just copy the diff file
+    individual_diffs = (
+        FileDiff.query.filter_by(file_path_id=file_path_id, rank=0)
+        .filter(FileDiff.version.between(33, 36))
+        .all()
+    )
+    create_blank_version(diff_project)  # v34
+    create_blank_version(diff_project)  # v35
+    create_blank_version(diff_project)  # v36
+    diff = FileDiff(
+        basefile=basefile, path=f"test.gpkg-diff-{uuid.uuid4()}", version=36, rank=1
+    )
+    db.session.add(diff)
+    db.session.commit()
+    diff.construct_checkpoint()
+    assert os.path.exists(diff.abs_path)
+    assert diffs_are_equal(diff.abs_path, individual_diffs[0].abs_path)
+
 
 def test_can_create_checkpoint(diff_project):
     """Test if diff file checkpoint can be created"""

server/migrations/community/bd1ec73db389_create_file_diff_table.py

@@ -62,27 +62,28 @@ def upgrade():
     # migrate data
     conn = op.get_bind()
     conn.execute(
-        """
+        sa.text(
+            """
         WITH diffs AS (
-            SELECT * 
-            FROM file_history 
+            SELECT *
+            FROM file_history
             WHERE diff IS NOT NULL
         ),
         basefiles AS (
-            SELECT DISTINCT 
-                fh.id AS basefile_id, 
+            SELECT DISTINCT
+                fh.id AS basefile_id,
                 fh.file_path_id,
                 fh.project_version_name AS basefile_version
             FROM diffs d
             LEFT OUTER JOIN file_history fh ON fh.file_path_id = d.file_path_id
-            WHERE 
+            WHERE
                 fh.change = ANY(ARRAY['create'::push_change_type, 'update'::push_change_type])
         ),
         relevant_basefiles AS (
-            SELECT 
-                d.id, 
-                d.project_version_name, 
-                b.basefile_id, 
+            SELECT
+                d.id,
+                d.project_version_name,
+                b.basefile_id,
                 b.basefile_version
             FROM diffs d
             LEFT OUTER JOIN basefiles b ON b.file_path_id = d.file_path_id AND b.basefile_version < d.project_version_name
@@ -104,6 +105,7 @@ def upgrade():
         -- it seems that some projects / files might be broken so we need to play it safe here
         SELECT * FROM file_diffs WHERE basefile_id IS NOT NULL;
         """
+        )
     )
 
     op.drop_column("file_history", "diff")
@@ -123,7 +125,8 @@ def downgrade():
     # migrate data
     conn = op.get_bind()
     conn.execute(
-        """
+        sa.text(
+            """
         UPDATE file_history fh
         SET diff = jsonb_build_object(
             'path', fd.path,
@@ -134,11 +137,13 @@ def downgrade():
         FROM file_diff fd
         WHERE fh.file_path_id = fd.file_path_id AND fh.project_version_name = fd.version AND fd.rank = 0;
         """
+        )
     )
 
     # if there were any broken gpkg files (ommited in upgrade), let's add there a dummy diff
     conn.execute(
-        """
+        sa.text(
+            """
         UPDATE file_history fh
         SET diff = jsonb_build_object(
             'path', 'missing-diff',
@@ -148,6 +153,7 @@ def downgrade():
         )
         WHERE fh.change = 'update_diff' AND fh.diff IS NULL;
         """
+        )
     )
 
     # add back consistency constraint