correctly handle case when requested changesets were cached and

download_file_diffs() call returns empty list of downloaded files

Author: alexbruy

mergin/client.py

@@ -12,6 +12,7 @@
 from datetime import datetime, timezone
 import dateutil.parser
 import ssl
+import re
 
 from .common import ClientError, LoginError, InvalidProject
 from .merginproject import MerginProject
@@ -779,6 +780,23 @@ def get_file_diff(self, project_dir, file_path, output_diff, version_from, versi
             self, project_path, file_path, version_from=version_from, version_to=version_to, file_history=file_history
         )
         diffs = self.download_file_diffs(project_dir, file_path, versions_to_fetch[1:])
+        # if some changesets were cached before, they will be missed from the
+        # list of downloaded changesets and should be added before any attempt
+        # to concatenate them into single file
+        sort = False
+        if len(diffs) < len(versions_to_fetch[1:]):
+            sort = True
+            for v in versions_to_fetch[1:]:
+                file_name = mp.fpath_cache(file_history["history"][v]["diff"]["path"], v)
+                if file_name not in diffs:
+                    diffs.append(file_name)
+
+        # at this point diffs in the list might be in the wrong order
+        # we need to sort them by version in ascending order
+        if sort:
+            ver_regex = re.compile("\/v[0-9]+\/")
+            diffs.sort(key=lambda x: int(ver_regex.search(x)[0].strip("/").replace("v", "")))
+
         # concatenate diffs, if needed
         output_dir = os.path.dirname(output_diff)
         if len(diffs) >= 1:

mergin/test/test_client.py

@@ -1764,3 +1764,50 @@ def test_report_failure(mc):
 
     warnings = create_report(mc, project_dir, "v1", "v5", report_file)
     assert warnings
+
+
+def test_changesets_download(mc):
+    """Check that downloading diffs works correctly, including case when
+    changesets are cached.
+    """
+    test_project = 'test_changesets_download'
+    project = API_USER + '/' + test_project
+    project_dir = os.path.join(TMP_DIR, test_project)  # primary project dir
+    test_gpkg = 'test.gpkg'
+    file_path = os.path.join(project_dir, 'test.gpkg')
+    download_dir = os.path.join(TMP_DIR, "changesets")
+
+    cleanup(mc, project, [project_dir])
+
+    os.makedirs(project_dir, exist_ok=True)
+    shutil.copy(os.path.join(TEST_DATA_DIR, 'base.gpkg'), file_path)
+    mc.create_project_and_push(test_project, project_dir)
+
+    shutil.copy(os.path.join(TEST_DATA_DIR, 'inserted_1_A.gpkg'), file_path)
+    mc.push_project(project_dir)
+
+    shutil.copy(os.path.join(TEST_DATA_DIR, 'inserted_1_A_mod.gpkg'), file_path)
+    mc.push_project(project_dir)
+
+    mp = MerginProject(project_dir)
+
+    os.makedirs(download_dir, exist_ok=True)
+    diff_file = os.path.join(download_dir, "base-v1-2.diff")
+    mc.get_file_diff(project_dir, test_gpkg, diff_file, "v1", "v2")
+    assert os.path.exists(diff_file)
+    assert mp.geodiff.has_changes(diff_file)
+    assert mp.geodiff.changes_count(diff_file) == 1
+
+    diff_file = os.path.join(download_dir, "base-v2-3.diff")
+    mc.get_file_diff(project_dir, test_gpkg, diff_file, "v2", "v3")
+    assert os.path.exists(diff_file)
+    assert mp.geodiff.has_changes(diff_file)
+    assert mp.geodiff.changes_count(diff_file) == 2
+
+    # even if changesets were cached and were not downloaded destination
+    # file should be created and contain a valid changeset
+    diff_file = os.path.join(download_dir, "base-all.diff")
+    mc.get_file_diff(project_dir, test_gpkg, diff_file, "v1", "v3")
+    assert os.path.exists(diff_file)
+    assert mp.geodiff.has_changes(diff_file)
+    assert mp.geodiff.changes_count(diff_file) == 3