feat: download object with versioned_id in key

Refs: #14

cubicweb_s3storage/storages.py

@@ -33,6 +33,7 @@
 
 class S3Storage(Storage):
     is_source_callback = True
+    KEY_SEPARATOR = '#'
 
     def __init__(self, bucket, suffix='.tmp'):
         self.s3cnx = self._s3_client()
@@ -57,7 +58,7 @@
             # FIXME need a way to check that the attribute is actually edited
             try:
                 suffixed_key = self.suffixed_key(key)
-                return self.download(suffixed_key)
+                self.get_s3_object(source, suffixed_key)
             except Exception:
                 pass
         try:
@@ -61,7 +62,7 @@
             except Exception:
                 pass
         try:
-            return self.download(key)
+            self.get_s3_object(source, key)
         except Exception as ex:
             source.critical("can't retrieve S3 object %s: %s", key, ex)
             return None
@@ -75,7 +76,7 @@
             if PY3:
                 key = key.decode('utf-8')
             try:
-                return self.download(key)
+                self.get_s3_object(entity, key)
             except Exception:
                 return None
 
@@ -175,7 +176,7 @@
         """
         Format the string that will store key and version id
         """
-        return f"{key}#{version_id}"
+        return f"{key}{self.KEY_SEPARATOR}{version_id}"
 
     def get_s3_key(self, entity, attr):
         """
@@ -206,8 +207,34 @@
     def suffixed_key(self, key):
         return key + self.suffix
 
-    def download(self, key):
-        result = self.s3cnx.get_object(Bucket=self.bucket, Key=key)
+    def get_s3_object(self, entity, key):
+        """
+        :param entiry: (Object)
+        :param key: (string)
+        get s3 stored attribute for entity
+        handle the case of versioned object
+        """
+
+        version_id = ""
+        # check  first : does the key contain a '<separator>'
+        try:
+            key, version_id = key.rsplit(self.KEY_SEPARATOR, 1)
+        except Exception as ex:
+            if entity._cw.repo.config['s3-activate-object-versioning']:
+                self.info(f"key for {entity.eid} was not versionned : {ex}")
+
+        # if object-versioning is activated use the version_id
+        if entity._cw.repo.config['s3-activate-object-versioning']:
+            return self.download(key, VersionId=version_id)
+        return self.download(key)
+
+    def download(self, key, **kwargs):
+        """
+        :param key: (string)
+        :param kwargs: (dict) Keys must be compatible with method S3.Client.put_object
+        https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/s3.html#S3.Client.put_object
+        """
+        result = self.s3cnx.get_object(Bucket=self.bucket, Key=key, **kwargs)
         self.info('Downloaded %s/%s from S3', self.bucket, key)
         return Binary(result['Body'].read())