models: bucket tags

* Adds support for adding tags (i.e. key/value-pairs) to buckets.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>

invenio_files_rest/models.py

@@ -27,6 +27,8 @@
 The entities of this module consists of:
 
  * Buckets - Identified by UUIDs, and contains objects.
+ * Buckets tags - Identified uniquely with a bucket by a key. Used to store
+   extra metadata for a bucket.
  * Objects - Identified uniquely within a bucket by string keys. Each object
    can have multiple object versions.
  * Object versions - Identified by UUIDs and belongs to one specific object
@@ -234,6 +236,10 @@ def snapshot(self, lock=False):
 
         return b
 
+    def get_tags(self):
+        """Get tags for bucket as dictionary."""
+        return {t.key: t.value for t in self.tags}
+
     @classmethod
     def create(cls, location=None, storage_class=None):
         """Create a bucket.
@@ -277,6 +283,74 @@ def all(cls):
         )
 
 
+class BucketTag(db.Model):
+    """Model for storing tags associated to buckets.
+
+    This is useful to store extra information for a bucket.
+    """
+
+    __tablename__ = 'files_buckettags'
+
+    bucket_id = db.Column(
+        UUIDType,
+        db.ForeignKey(Bucket.id, ondelete='CASCADE'),
+        default=uuid.uuid4,
+        primary_key=True, )
+
+    key = db.Column(db.String(255), primary_key=True)
+    """Tag key."""
+
+    value = db.Column(db.Text, nullable=False)
+    """Tag value."""
+
+    bucket = db.relationship(Bucket, backref='tags')
+    """Relationship to buckets."""
+
+    @classmethod
+    def get(cls, bucket, key):
+        """Get tag object."""
+        return cls.query.filter_by(
+            bucket_id=bucket.id if isinstance(bucket, Bucket) else bucket,
+            key=key,
+        ).one_or_none()
+
+    @classmethod
+    def create(cls, bucket, key, value):
+        """Create a new tag for bucket."""
+        with db.session.begin_nested():
+            obj = cls(
+                bucket_id=bucket.id if isinstance(bucket, Bucket) else bucket,
+                key=key,
+                value=value
+            )
+            db.session.add(obj)
+        return obj
+
+    @classmethod
+    def create_or_update(cls, bucket, key, value):
+        """Create a new tag for bucket."""
+        obj = cls.get(bucket, key)
+        if obj:
+            obj.value = value
+        else:
+            cls.create(bucket, key, value)
+
+    @classmethod
+    def get_value(cls, bucket, key):
+        """Get tag value."""
+        obj = cls.get(bucket, key)
+        return obj.value if obj else None
+
+    @classmethod
+    def delete(cls, bucket, key):
+        """Delete a tag."""
+        with db.session.begin_nested():
+            cls.query.filter_by(
+                bucket_id=bucket.id if isinstance(bucket, Bucket) else bucket,
+                key=key,
+            ).delete()
+
+
 class FileInstance(db.Model, Timestamp):
     """Model for storing files.
 

tests/test_models.py

@@ -32,8 +32,8 @@
 
 from invenio_files_rest.errors import FileInstanceAlreadySetError, \
     InvalidOperationError
-from invenio_files_rest.models import Bucket, FileInstance, Location, \
-    ObjectVersion
+from invenio_files_rest.models import Bucket, BucketTag, FileInstance, \
+    Location, ObjectVersion
 
 
 def test_location(app, db):
@@ -475,3 +475,44 @@ def test_object_restore(app, db, dummy_location):
     assert obj_new.key == obj1.key
     assert obj_new.file_id == obj1.file_id
     assert obj_new.bucket == obj1.bucket
+
+
+def test_bucket_tags(app, db, dummy_location):
+    """Test bucket tags."""
+    b = Bucket.create()
+    BucketTag.create(b, "mykey", "testvalue")
+    BucketTag.create(b, "another_key", "another value")
+    db.session.commit()
+
+    # Duplicate key
+    pytest.raises(Exception, BucketTag.create, b, "mykey", "newvalue")
+
+    # Test get
+    assert BucketTag.query.count() == 2
+    assert BucketTag.get(b.id, "mykey").value == "testvalue"
+    assert BucketTag.get_value(b, "another_key") == "another value"
+    assert BucketTag.get_value(b.id, "invalid") is None
+
+    # Test delete
+    BucketTag.delete(b, "mykey")
+    assert BucketTag.query.count() == 1
+    BucketTag.delete(b, "invalid")
+    assert BucketTag.query.count() == 1
+
+    # Create or update
+    BucketTag.create_or_update(b, "another_key", "newval")
+    BucketTag.create_or_update(b, "newkey", "testval")
+    db.session.commit()
+    assert BucketTag.get_value(b, "another_key") == "newval"
+    assert BucketTag.get_value(b, "newkey") == "testval"
+
+    # Get tags as dictionary
+    assert b.get_tags() == dict(another_key="newval", newkey="testval")
+
+    b2 = Bucket.create()
+    assert b2.get_tags() == dict()
+
+    # Test cascading delete.
+    Bucket.query.delete()
+    db.session.commit()
+    assert BucketTag.query.count() == 0