Add support for retrieving attachment metadata

This commit adds support for getting details about a specific
attachment, and for getting a list of attachments related to a
specific story, to the attachments endpoint.

Change-Id: Ic4c945167fad77c304f46efc677eaec04426d49b
Story: 2000679
Task: 29116

storyboard/api/v1/attachments.py

@@ -14,14 +14,20 @@
 # limitations under the License.
 
 from oslo_config import cfg
+from pecan import request
 from pecan import response
 from pecan import rest
 from pecan.secure import secure
 from wsme import types as wtypes
 import wsmeext.pecan as wsme_pecan
 
+from storyboard._i18n import _
 from storyboard.api.auth import authorization_checks as checks
 from storyboard.api.v1.storage import storage
+from storyboard.api.v1 import wmodels
+from storyboard.common import decorators
+from storyboard.common import exception as exc
+from storyboard.db.api import attachments as attachments_api
 
 
 CONF = cfg.CONF
@@ -54,3 +60,50 @@ class AttachmentsController(rest.RestController):
         response.headers['X-Object-Name'] = name
 
         return STORAGE_BACKEND.get_upload_url()
+
+    @decorators.db_exceptions
+    @secure(checks.guest)
+    @wsme_pecan.wsexpose(wmodels.Attachment, int, int)
+    def get_one(self, story_id, attachment_id):
+        """Retrieve details about a single attachment.
+
+        Example::
+
+          curl https://my.example.org/api/v1/stories/1/attachments/1
+
+        :param story_id: ID of the story which has the attachment.
+        :param attachment_id: ID of the attachment to retrieve details
+            about.
+
+        """
+        attachment = attachments_api.get_by_id(
+            attachment_id, current_user=request.current_user_id)
+
+        if attachment:
+            return wmodels.Attachment.from_db_model(attachment)
+        raise exc.NotFound(_("Attachment %s not found") % attachment_id)
+
+    @decorators.db_exceptions
+    @secure(checks.guest)
+    @wsme_pecan.wsexpose([wmodels.Attachment], int)
+    def get_all(self, story_id):
+        """Retrieve details about all attachments for a given story.
+
+        Example::
+
+          curl https://my.example.org/api/v1/stories/1/attachments
+
+        :param story_id: ID of the story to view attachments of.
+
+        """
+        attachments = attachments_api.get_all(
+            story_id=story_id,
+            current_user=request.current_user_id
+        )
+        attachment_count = attachments_api.get_count(
+            story_id=story_id,
+            current_user=request.current_user_id
+        )
+
+        response.headers['X-Total'] = str(attachment_count)
+        return [wmodels.Attachment.from_db_model(a) for a in attachments]

storyboard/db/api/attachments.py

@@ -0,0 +1,53 @@
+# Copyright (c) 2019 Adam Coldrick
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from storyboard.db.api import base as api_base
+from storyboard.db import models
+
+
+def get_by_id(attachment_id, current_user=None, session=None):
+    query = api_base.model_query(models.Attachment, session=session)
+    query = query.filter(models.Attachment.id == attachment_id)
+
+    # Filter out attachments related to stories that the current user lacks
+    # permissions to see
+    query = query.join(models.Story)
+    query = api_base.filter_private_stories(query, current_user)
+
+    return query.first()
+
+
+def _build_query(current_user=None, session=None, **kwargs):
+    query = api_base.model_query(models.Attachment, session=session)
+    query = api_base.apply_query_filters(query=query,
+                                         model=models.Attachment,
+                                         **kwargs)
+
+    # Filter out attachments related to stories that the current user lacks
+    # permissions to see
+    query = query.join(models.Story)
+    query = api_base.filter_private_stories(query, current_user)
+
+    return query
+
+
+def get_all(current_user=None, session=None, **kwargs):
+    query = _build_query(current_user=current_user, session=session, **kwargs)
+    return query.all()
+
+
+def get_count(current_user=None, session=None, **kwargs):
+    query = _build_query(current_user=current_user, session=session, **kwargs)
+    return query.count()