We can now save changes to metadata

genweb/metadata.py

@@ -6,8 +6,10 @@
 
 from glob import glob
 from copy import deepcopy
+from os.path import splitext
+from datetime import datetime
 
-from yaml import safe_load
+from yaml import safe_load, safe_dump
 
 
 def load_yaml(path: str) -> dict[str, dict]:
@@ -24,20 +26,47 @@ def load_yaml(path: str) -> dict[str, dict]:
 
 
 class Metadata:
-    """read-only-dict-like object"""
+    """dict-like object
+    When loading from file name.ext revisions are saved to name YYYY-MM-DD HH:MM:SS.ext
+    Revisions saved earlier are preserved, but overridden by later revisions
+    """
+
+    def __init__(self, path: str):
+        self.path = path  # original file
 
-    def __init__(self, path_pattern: str):
-        self.path = path_pattern
-        self.original = Metadata.__load(path_pattern)
+        # Calculate the file we will save any changes to
+        base, extension = splitext(path)
+        now = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+        self.revision_path = f"{base} {now}{extension}"
+
+        # load all the revisions
+        self.original = Metadata.__load(path)
         self.updated = {}
 
+    def save(self) -> None:
+        """If there are changes saves them to the revision file"""
+        if not self.updated:
+            return
+
+        with open(self.revision_path, "w", encoding="utf-8") as revision_file:
+            safe_dump(self.updated, revision_file)
+
     @staticmethod
-    def __load(path_pattern: str) -> dict[str:dict]:
+    def __load(path: str) -> dict[str:dict]:
         result = {}
 
-        for path in sorted(glob(path_pattern)):
-            result.update(Metadata.__validate(load_yaml(path)))
-
+        # Revisions are stored as: base YYYY-mm-dd HH:MM:SS.ext
+        base, extension = splitext(path)
+        revisions = glob(base + "*" + extension)
+        # ensure we load the original file first
+        revisions.remove(path)
+        revisions.sort()
+        revisions.insert(0, path)
+
+        # load them in order to have later override earlier
+        for revision_path in revisions:
+            revision = Metadata.__validate(load_yaml(revision_path))
+            result.update(revision)
         return result
 
     @staticmethod
@@ -54,6 +83,8 @@ def __combined(self, deep=False) -> dict[str:dict]:
 
         return combined
 
+    # MARK: dict methods
+
     def __getitem__(self, key: str) -> dict:
         if key in self.updated:
             return deepcopy(self.updated[key])

tests/test_metadata.py

@@ -4,6 +4,8 @@
 
 
 from os.path import dirname, join
+from shutil import copy
+from tempfile import TemporaryDirectory
 
 
 from genweb.metadata import load_yaml, Metadata
@@ -12,8 +14,33 @@
 DATA_DIR = join(dirname(__file__), "data")
 
 
+def test_metadata_save() -> None:
+    with TemporaryDirectory() as working_dir:
+        src_file = join(DATA_DIR, "example.yml")
+        metadata_file = join(working_dir, "example.yml")
+        copy(src_file, metadata_file)
+        metadata = Metadata(metadata_file)
+        johns_picture = metadata["1700000000WilliamsJohn1665DavisRebecca1639"]
+        johns_picture["width"] = 500
+        metadata["1700000000WilliamsJohn1665DavisRebecca1639"] = johns_picture
+        assert metadata["1700000000WilliamsJohn1665DavisRebecca1639"]["width"] == 500
+        metadata.save()
+
+        metadata = Metadata(metadata_file)
+        assert metadata["1700000000WilliamsJohn1665DavisRebecca1639"]["width"] == 500
+        metadata.save()
+
+        with open(src_file, "r", encoding="utf-8") as file:
+            original = file.read()
+
+        with open(metadata_file, "r", encoding="utf-8") as file:
+            copied = file.read()
+
+        assert original == copied, "base metadata file was modified"
+
+
 def test_metadata_update() -> None:
-    metadata = Metadata(join(DATA_DIR, "layered.*.yml"))
+    metadata = Metadata(join(DATA_DIR, "layered.yml"))
     metadata["0000000000PageMarcA1973HislopMickieL1949"] = {
         "type": "inline",
         "content": "hello",
@@ -38,7 +65,7 @@ def test_metadata_update() -> None:
 
 
 def test_metadata() -> None:
-    metadata = Metadata(join(DATA_DIR, "layered.*.yml"))
+    metadata = Metadata(join(DATA_DIR, "layered.yml"))
     assert "0000000000SmithCaleb1765JonesMary1724" in metadata
     assert "0000000000JohnsonSamI1892MillerJane1860" in metadata
     assert "1700000000WilliamsJohn1665DavisRebecca1639" in metadata
@@ -99,3 +126,4 @@ def test_load_yaml() -> None:
     test_load_yaml()
     test_metadata()
     test_metadata_update()
+    test_metadata_save()