support versioned open (#39)

* support versioned open

* bump version

baiji/cached_file.py

@@ -59,7 +59,7 @@ class CachedFile(object):
     CachedFile('s3://bucket/path/to/file.ext', 'w') opens a temp file for writing and uploads it on close
     CachedFile('s3://bucket/path/to/file.ext', 'x') verifies that the file doesn't exist on s3, then behaves like 'w'
     '''
-    def __init__(self, key, mode='r', connection=None, encrypt=True):
+    def __init__(self, key, mode='r', connection=None, encrypt=True, version_id=None):
         from baiji.connection import S3Connection
         self.encrypt = encrypt
         self.key = key
@@ -110,7 +110,7 @@ def __init__(self, key, mode='r', connection=None, encrypt=True):
             self.name = self.f.name
             self.remotename = key # Used by some serialization code to find files which sit along side the file in question, like textures which sit next to a mesh file
             if self.mode.reading:
-                self.connection.cp(self.key, self.name, force=True)
+                self.connection.cp(self.key, self.name, force=True, version_id=version_id)
     def upload(self):
         self.connection.cp(self.name, self.key, encrypt=self.encrypt, force=True)
     def __enter__(self):

baiji/package_version.py

@@ -5,4 +5,4 @@
 #
 # See https://www.python.org/dev/peps/pep-0420/#namespace-packages-today
 
-__version__ = '2.7.2'
+__version__ = '2.8.0'

baiji/s3.py

@@ -96,7 +96,7 @@ def enable_versioning(*args, **kwargs):
 def disable_versioning(*args, **kwargs):
     return S3Connection().disable_versioning(*args, **kwargs)
 
-def open(key, mode='rb'): # pylint: disable=redefined-builtin
+def open(key, mode='rb', version_id=None): # pylint: disable=redefined-builtin
     '''
     Acts like open(key, mode), opening a file.
 
@@ -121,6 +121,8 @@ def open(key, mode='rb'): # pylint: disable=redefined-builtin
     existing file or key, ValueError for an invalid key, and IOError for an
     underlying local file-system failure.
 
+    version_id: comes handy when opening remote versioned files. no-op otherwise
+
     '''
     from baiji.cached_file import CachedFile
-    return CachedFile(key, mode)
+    return CachedFile(key, mode, version_id=version_id)

baiji/test_s3_cached_file.py

@@ -209,6 +209,22 @@ def test_s3_open_read_raises_error_for_nonexistent_remote_file(self):
         with self.assertRaises(s3.KeyNotFound):
             s3.open(nonexistent_file, 'r')
 
+    def test_s3_open_read_versioned_remote_file(self):
+        remote_file_name = self.existing_versioned_remote_file
+        version_id = s3.info(remote_file_name)['version_id']
+
+        with s3.open(remote_file_name, 'r', version_id=version_id) as f:
+            tempname = f.name
+
+        self.assertFalse(os.path.exists(tempname))
+
+    def test_s3_open_read_versioned_remote_file_with_unkown_version_id_raise_key_not_found(self):
+        remote_file_name = self.existing_versioned_remote_file
+        unknown_version_id = '5elgojhtA8BGJerqfbciN78eU74SJ9mX'
+
+        with self.assertRaises(s3.KeyNotFound):
+            s3.open(remote_file_name, 'r', version_id=unknown_version_id)
+
     def test_s3_open_write_does_not_raise_error_for_nonexistent_remote_file(self):
         nonexistent_file = self.remote_file(str(uuid.uuid4()))
         self.assert_s3_does_not_exist(nonexistent_file)