server/general: move not found errors to func

20 files changed, 134 insertions, 207 deletions

diff --git a/server/szurubooru/api/comment_api.py b/server/szurubooru/api/comment_api.py
index d1201ff..7f675d1 100644
--- a/server/szurubooru/api/comment_api.py
+++ b/server/szurubooru/api/comment_api.py
@@ -18,12 +18,9 @@ class CommentListApi(BaseApi):
 
     def post(self, ctx):
         auth.verify_privilege(ctx.user, 'comments:create')
-
         text = ctx.get_param_as_string('text', required=True)
         post_id = ctx.get_param_as_int('postId', required=True)
         post = posts.get_post_by_id(post_id)
-        if not post:
-            raise posts.PostNotFoundError('Post %r not found.' % post_id)
         comment = comments.create_comment(ctx.user, post, text)
         ctx.session.add(comment)
         ctx.session.commit()
@@ -33,41 +30,21 @@ class CommentDetailApi(BaseApi):
     def get(self, ctx, comment_id):
         auth.verify_privilege(ctx.user, 'comments:view')
         comment = comments.get_comment_by_id(comment_id)
-        if not comment:
-            raise comments.CommentNotFoundError(
-                'Comment %r not found.' % comment_id)
         return {'comment': comments.serialize_comment(comment, ctx.user)}
 
     def put(self, ctx, comment_id):
         comment = comments.get_comment_by_id(comment_id)
-        if not comment:
-            raise comments.CommentNotFoundError(
-                'Comment %r not found.' % comment_id)
-
-        if ctx.user.user_id == comment.user_id:
-            infix = 'self'
-        else:
-            infix = 'any'
-
-        comment.last_edit_time = datetime.datetime.now()
-        auth.verify_privilege(ctx.user, 'comments:edit:%s' % infix)
+        infix = 'self' if ctx.user.user_id == comment.user_id else 'any'
         text = ctx.get_param_as_string('text', required=True)
+        auth.verify_privilege(ctx.user, 'comments:edit:%s' % infix)
+        comment.last_edit_time = datetime.datetime.now()
         comments.update_comment_text(comment, text)
-
         ctx.session.commit()
         return {'comment': comments.serialize_comment(comment, ctx.user)}
 
     def delete(self, ctx, comment_id):
         comment = comments.get_comment_by_id(comment_id)
-        if not comment:
-            raise comments.CommentNotFoundError(
-                'Comment %r not found.' % comment_id)
-
-        if ctx.user.user_id == comment.user_id:
-            infix = 'self'
-        else:
-            infix = 'any'
-
+        infix = 'self' if ctx.user.user_id == comment.user_id else 'any'
         auth.verify_privilege(ctx.user, 'comments:delete:%s' % infix)
         ctx.session.delete(comment)
         ctx.session.commit()
diff --git a/server/szurubooru/api/context.py b/server/szurubooru/api/context.py
index 3b725fc..58890e0 100644
--- a/server/szurubooru/api/context.py
+++ b/server/szurubooru/api/context.py
@@ -50,19 +50,15 @@ class Context(object):
                 raise errors.ValidationError(
                     'Parameter %r is invalid: the value must be an integer.'
                     % name)
-
             if min is not None and val < min:
                 raise errors.ValidationError(
                     'Parameter %r is invalid: the value must be at least %r.'
                     % (name, min))
-
             if max is not None and val > max:
                 raise errors.ValidationError(
                     'Parameter %r is invalid: the value may not exceed %r.'
                     % (name, max))
-
             return val
-
         if not required:
             return default
         raise errors.ValidationError(
diff --git a/server/szurubooru/api/info_api.py b/server/szurubooru/api/info_api.py
index d6c32e8..29043b7 100644
--- a/server/szurubooru/api/info_api.py
+++ b/server/szurubooru/api/info_api.py
@@ -11,7 +11,7 @@ class InfoApi(BaseApi):
         self._cache_result = None
 
     def get(self, ctx):
-        featured_post = posts.get_featured_post()
+        featured_post = posts.try_get_featured_post()
         return {
             'postCount': posts.get_post_count(),
             'diskUsage': self._get_disk_usage(),
diff --git a/server/szurubooru/api/password_reset_api.py b/server/szurubooru/api/password_reset_api.py
index 9346670..cca9576 100644
--- a/server/szurubooru/api/password_reset_api.py
+++ b/server/szurubooru/api/password_reset_api.py
@@ -12,8 +12,6 @@ class PasswordResetApi(BaseApi):
     def get(self, _ctx, user_name):
         ''' Send a mail with secure token to the correlated user. '''
         user = users.get_user_by_name_or_email(user_name)
-        if not user:
-            raise errors.NotFoundError('User %r not found.' % user_name)
         if not user.email:
             raise errors.ValidationError(
                 'User %r hasn\'t supplied email. Cannot reset password.' % user_name)
@@ -30,8 +28,6 @@ class PasswordResetApi(BaseApi):
     def post(self, ctx, user_name):
         ''' Verify token from mail, generate a new password and return it. '''
         user = users.get_user_by_name_or_email(user_name)
-        if not user:
-            raise errors.NotFoundError('User %r not found.' % user_name)
         good_token = auth.generate_authentication_token(user)
         token = ctx.get_param_as_string('token', required=True)
         if token != good_token:
diff --git a/server/szurubooru/api/post_api.py b/server/szurubooru/api/post_api.py
index 23df5c7..7565b92 100644
--- a/server/szurubooru/api/post_api.py
+++ b/server/szurubooru/api/post_api.py
@@ -6,9 +6,7 @@ class PostFeatureApi(BaseApi):
         auth.verify_privilege(ctx.user, 'posts:feature')
         post_id = ctx.get_param_as_int('id', required=True)
         post = posts.get_post_by_id(post_id)
-        if not post:
-            raise posts.PostNotFoundError('Post %r not found.' % post_id)
-        featured_post = posts.get_featured_post()
+        featured_post = posts.try_get_featured_post()
         if featured_post and featured_post.post_id == post.post_id:
             raise posts.PostAlreadyFeaturedError(
                 'Post %r is already featured.' % post_id)
@@ -20,5 +18,5 @@ class PostFeatureApi(BaseApi):
         return posts.serialize_post_with_details(post, ctx.user)
 
     def get(self, ctx):
-        post = posts.get_featured_post()
+        post = posts.try_get_featured_post()
         return posts.serialize_post_with_details(post, ctx.user)
diff --git a/server/szurubooru/api/tag_api.py b/server/szurubooru/api/tag_api.py
index e13b880..9907821 100644
--- a/server/szurubooru/api/tag_api.py
+++ b/server/szurubooru/api/tag_api.py
@@ -35,31 +35,22 @@ class TagDetailApi(BaseApi):
     def get(self, ctx, tag_name):
         auth.verify_privilege(ctx.user, 'tags:view')
         tag = tags.get_tag_by_name(tag_name)
-        if not tag:
-            raise tags.TagNotFoundError('Tag %r not found.' % tag_name)
         return tags.serialize_tag_with_details(tag)
 
     def put(self, ctx, tag_name):
         tag = tags.get_tag_by_name(tag_name)
-        if not tag:
-            raise tags.TagNotFoundError('Tag %r not found.' % tag_name)
-
         if ctx.has_param('names'):
             auth.verify_privilege(ctx.user, 'tags:edit:names')
             tags.update_names(tag, ctx.get_param_as_list('names'))
-
         if ctx.has_param('category'):
             auth.verify_privilege(ctx.user, 'tags:edit:category')
             tags.update_category_name(tag, ctx.get_param_as_string('category'))
-
         if ctx.has_param('suggestions'):
             auth.verify_privilege(ctx.user, 'tags:edit:suggestions')
             tags.update_suggestions(tag, ctx.get_param_as_list('suggestions'))
-
         if ctx.has_param('implications'):
             auth.verify_privilege(ctx.user, 'tags:edit:implications')
             tags.update_implications(tag, ctx.get_param_as_list('implications'))
-
         tag.last_edit_time = datetime.datetime.now()
         ctx.session.flush()
         snapshots.modify(tag, ctx.user)
@@ -69,13 +60,10 @@ class TagDetailApi(BaseApi):
 
     def delete(self, ctx, tag_name):
         tag = tags.get_tag_by_name(tag_name)
-        if not tag:
-            raise tags.TagNotFoundError('Tag %r not found.' % tag_name)
         if tag.post_count > 0:
             raise tags.TagIsInUseError(
                 'Tag has some usages and cannot be deleted. ' +
                 'Please untag relevant posts first.')
-
         auth.verify_privilege(ctx.user, 'tags:delete')
         snapshots.delete(tag, ctx.user)
         ctx.session.delete(tag)
@@ -89,15 +77,8 @@ class TagMergeApi(BaseApi):
         target_tag_name = ctx.get_param_as_string('merge-to', required=True) or ''
         source_tag = tags.get_tag_by_name(source_tag_name)
         target_tag = tags.get_tag_by_name(target_tag_name)
-        if not source_tag:
-            raise tags.TagNotFoundError(
-                'Source tag %r not found.' % source_tag_name)
-        if not target_tag:
-            raise tags.TagNotFoundError(
-                'Source tag %r not found.' % target_tag_name)
         if source_tag.tag_id == target_tag.tag_id:
-            raise tags.InvalidTagRelationError(
-                'Cannot merge tag with itself.')
+            raise tags.InvalidTagRelationError('Cannot merge tag with itself.')
         auth.verify_privilege(ctx.user, 'tags:merge')
         snapshots.delete(source_tag, ctx.user)
         tags.merge_tags(source_tag, target_tag)
@@ -109,8 +90,6 @@ class TagSiblingsApi(BaseApi):
     def get(self, ctx, tag_name):
         auth.verify_privilege(ctx.user, 'tags:view')
         tag = tags.get_tag_by_name(tag_name)
-        if not tag:
-            raise tags.TagNotFoundError('Tag %r not found.' % tag_name)
         result = tags.get_siblings(tag)
         serialized_siblings = []
         for sibling, occurrences in result:
diff --git a/server/szurubooru/api/tag_category_api.py b/server/szurubooru/api/tag_category_api.py
index bc6cbf3..798fa1f 100644
--- a/server/szurubooru/api/tag_category_api.py
+++ b/server/szurubooru/api/tag_category_api.py
@@ -7,7 +7,8 @@ class TagCategoryListApi(BaseApi):
         categories = tag_categories.get_all_categories()
         return {
             'tagCategories': [
-                tags.serialize_category(category) for category in categories],
+                tag_categories.serialize_category(category) \
+                    for category in categories],
         }
 
     def post(self, ctx):
@@ -20,22 +21,16 @@ class TagCategoryListApi(BaseApi):
         snapshots.create(category, ctx.user)
         ctx.session.commit()
         tags.export_to_json()
-        return tags.serialize_category_with_details(category)
+        return tag_categories.serialize_category_with_details(category)
 
 class TagCategoryDetailApi(BaseApi):
     def get(self, ctx, category_name):
         auth.verify_privilege(ctx.user, 'tag_categories:view')
         category = tag_categories.get_category_by_name(category_name)
-        if not category:
-            raise tag_categories.TagCategoryNotFoundError(
-                'Tag category %r not found.' % category_name)
-        return tags.serialize_category_with_details(category)
+        return tag_categories.serialize_category_with_details(category)
 
     def put(self, ctx, category_name):
         category = tag_categories.get_category_by_name(category_name)
-        if not category:
-            raise tag_categories.TagCategoryNotFoundError(
-                'Tag category %r not found.' % category_name)
         if ctx.has_param('name'):
             auth.verify_privilege(ctx.user, 'tag_categories:edit:name')
             tag_categories.update_name(
@@ -48,13 +43,10 @@ class TagCategoryDetailApi(BaseApi):
         snapshots.modify(category, ctx.user)
         ctx.session.commit()
         tags.export_to_json()
-        return tags.serialize_category_with_details(category)
+        return tag_categories.serialize_category_with_details(category)
 
     def delete(self, ctx, category_name):
         category = tag_categories.get_category_by_name(category_name)
-        if not category:
-            raise tag_categories.TagCategoryNotFoundError(
-                'Tag category %r not found.' % category_name)
         auth.verify_privilege(ctx.user, 'tag_categories:delete')
         if len(tag_categories.get_all_category_names()) == 1:
             raise tag_categories.TagCategoryIsInUseError(
diff --git a/server/szurubooru/api/user_api.py b/server/szurubooru/api/user_api.py
index 4ba2d7a..4c91fee 100644
--- a/server/szurubooru/api/user_api.py
+++ b/server/szurubooru/api/user_api.py
@@ -14,22 +14,17 @@ class UserListApi(BaseApi):
 
     def post(self, ctx):
         auth.verify_privilege(ctx.user, 'users:create')
-
         name = ctx.get_param_as_string('name', required=True)
         password = ctx.get_param_as_string('password', required=True)
         email = ctx.get_param_as_string('email', required=False, default='')
-
         user = users.create_user(name, password, email, ctx.user)
-
         if ctx.has_param('rank'):
             users.update_rank(user, ctx.get_param_as_string('rank'), ctx.user)
-
         if ctx.has_param('avatarStyle'):
             users.update_avatar(
                 user,
                 ctx.get_param_as_string('avatarStyle'),
                 ctx.get_file('avatar'))
-
         ctx.session.add(user)
         ctx.session.commit()
         return {'user': users.serialize_user(user, ctx.user)}
@@ -38,56 +33,35 @@ class UserDetailApi(BaseApi):
     def get(self, ctx, user_name):
         auth.verify_privilege(ctx.user, 'users:view')
         user = users.get_user_by_name(user_name)
-        if not user:
-            raise users.UserNotFoundError('User %r not found.' % user_name)
         return {'user': users.serialize_user(user, ctx.user)}
 
     def put(self, ctx, user_name):
         user = users.get_user_by_name(user_name)
-        if not user:
-            raise users.UserNotFoundError('User %r not found.' % user_name)
-
-        if ctx.user.user_id == user.user_id:
-            infix = 'self'
-        else:
-            infix = 'any'
-
+        infix = 'self' if ctx.user.user_id == user.user_id else 'any'
         if ctx.has_param('name'):
             auth.verify_privilege(ctx.user, 'users:edit:%s:name' % infix)
             users.update_name(user, ctx.get_param_as_string('name'), ctx.user)
-
         if ctx.has_param('password'):
             auth.verify_privilege(ctx.user, 'users:edit:%s:pass' % infix)
             users.update_password(user, ctx.get_param_as_string('password'))
-
         if ctx.has_param('email'):
             auth.verify_privilege(ctx.user, 'users:edit:%s:email' % infix)
             users.update_email(user, ctx.get_param_as_string('email'))
-
         if ctx.has_param('rank'):
             auth.verify_privilege(ctx.user, 'users:edit:%s:rank' % infix)
             users.update_rank(user, ctx.get_param_as_string('rank'), ctx.user)
-
         if ctx.has_param('avatarStyle'):
             auth.verify_privilege(ctx.user, 'users:edit:%s:avatar' % infix)
             users.update_avatar(
                 user,
                 ctx.get_param_as_string('avatarStyle'),
                 ctx.get_file('avatar'))
-
         ctx.session.commit()
         return {'user': users.serialize_user(user, ctx.user)}
 
     def delete(self, ctx, user_name):
         user = users.get_user_by_name(user_name)
-        if not user:
-            raise users.UserNotFoundError('User %r not found.' % user_name)
-
-        if ctx.user.user_id == user.user_id:
-            infix = 'self'
-        else:
-            infix = 'any'
-
+        infix = 'self' if ctx.user.user_id == user.user_id else 'any'
         auth.verify_privilege(ctx.user, 'users:delete:%s' % infix)
         ctx.session.delete(user)
         ctx.session.commit()
diff --git a/server/szurubooru/func/comments.py b/server/szurubooru/func/comments.py
index 873bc7d..576cca2 100644
--- a/server/szurubooru/func/comments.py
+++ b/server/szurubooru/func/comments.py
@@ -15,12 +15,18 @@ def serialize_comment(comment, authenticated_user):
         'lastEditTime': comment.last_edit_time,
     }
 
-def get_comment_by_id(comment_id):
+def try_get_comment_by_id(comment_id):
     return db.session \
         .query(db.Comment) \
         .filter(db.Comment.comment_id == comment_id) \
         .one_or_none()
 
+def get_comment_by_id(comment_id):
+    comment = try_get_comment_by_id(comment_id)
+    if comment:
+        return comment
+    raise CommentNotFoundError('Comment %r not found.' % comment_id)
+
 def create_comment(user, post, text):
     comment = db.Comment()
     comment.user = user
diff --git a/server/szurubooru/func/posts.py b/server/szurubooru/func/posts.py
index 8811caa..5d947b2 100644
--- a/server/szurubooru/func/posts.py
+++ b/server/szurubooru/func/posts.py
@@ -49,13 +49,19 @@ def serialize_post_with_details(post, authenticated_user):
 def get_post_count():
     return db.session.query(sqlalchemy.func.count(db.Post.post_id)).one()[0]
 
-def get_post_by_id(post_id):
+def try_get_post_by_id(post_id):
     return db.session \
         .query(db.Post) \
         .filter(db.Post.post_id == post_id) \
         .one_or_none()
 
-def get_featured_post():
+def get_post_by_id(post_id):
+    post = try_get_post_by_id(post_id)
+    if not post:
+        raise PostNotFoundError('Post %r not found.' % post_id)
+    return post
+
+def try_get_featured_post():
     post_feature = db.session \
         .query(db.PostFeature) \
         .order_by(db.PostFeature.time.desc()) \
diff --git a/server/szurubooru/func/tag_categories.py b/server/szurubooru/func/tag_categories.py
index c4a55cd..90bb387 100644
--- a/server/szurubooru/func/tag_categories.py
+++ b/server/szurubooru/func/tag_categories.py
@@ -1,6 +1,6 @@
 import re
 from szurubooru import config, db, errors
-from szurubooru.func import util
+from szurubooru.func import util, snapshots
 
 class TagCategoryNotFoundError(errors.NotFoundError): pass
 class TagCategoryAlreadyExistsError(errors.ValidationError): pass
@@ -14,6 +14,18 @@ def _verify_name_validity(name):
         raise InvalidTagCategoryNameError(
             'Name must satisfy regex %r.' % name_regex)
 
+def serialize_category(category):
+    return {
+        'name': category.name,
+        'color': category.color,
+    }
+
+def serialize_category_with_details(category):
+    return {
+        'tagCategory': serialize_category(category),
+        'snapshots': snapshots.get_serialized_history(category),
+    }
+
 def create_category(name, color):
     category = db.TagCategory()
     update_name(category, name)
@@ -42,11 +54,17 @@ def update_color(category, color):
         raise InvalidTagCategoryColorError('Color is too long.')
     category.color = color
 
-def get_category_by_name(name):
+def try_get_category_by_name(name):
     return db.session \
         .query(db.TagCategory) \
         .filter(db.TagCategory.name.ilike(name)) \
-        .first()
+        .one_or_none()
+
+def get_category_by_name(name):
+    category = try_get_category_by_name(name)
+    if not category:
+        raise TagCategoryNotFoundError('Tag category %r not found.' % name)
+    return category
 
 def get_all_category_names():
     return [row[0] for row in db.session.query(db.TagCategory.name).all()]
@@ -54,9 +72,15 @@ def get_all_category_names():
 def get_all_categories():
     return db.session.query(db.TagCategory).all()
 
-def get_default_category():
+def try_get_default_category():
     return db.session \
         .query(db.TagCategory) \
         .order_by(db.TagCategory.tag_category_id.asc()) \
         .limit(1) \
         .one()
+
+def get_default_category():
+    category = try_get_default_category()
+    if not category:
+        raise TagCategoryNotFoundError('No tag category created yet.')
+    return category
diff --git a/server/szurubooru/func/tags.py b/server/szurubooru/func/tags.py
index 7b5c70f..14619a0 100644
--- a/server/szurubooru/func/tags.py
+++ b/server/szurubooru/func/tags.py
@@ -13,6 +13,20 @@ class InvalidTagNameError(errors.ValidationError): pass
 class InvalidTagCategoryError(errors.ValidationError): pass
 class InvalidTagRelationError(errors.ValidationError): pass
 
+def _verify_name_validity(name):
+    name_regex = config.config['tag_name_regex']
+    if not re.match(name_regex, name):
+        raise InvalidTagNameError('Name must satisfy regex %r.' % name_regex)
+
+def _get_plain_names(tag):
+    return [tag_name.name for tag_name in tag.names]
+
+def _lower_list(names):
+    return [name.lower() for name in names]
+
+def _check_name_intersection(names1, names2):
+    return len(set(_lower_list(names1)).intersection(_lower_list(names2))) > 0
+
 def serialize_tag(tag):
     return {
         'names': [tag_name.name for tag_name in tag.names],
@@ -31,32 +45,6 @@ def serialize_tag_with_details(tag):
         'snapshots': snapshots.get_serialized_history(tag),
     }
 
-def serialize_category(category):
-    return {
-        'name': category.name,
-        'color': category.color,
-    }
-
-def serialize_category_with_details(category):
-    return {
-        'tagCategory': serialize_category(category),
-        'snapshots': snapshots.get_serialized_history(category),
-    }
-
-def _verify_name_validity(name):
-    name_regex = config.config['tag_name_regex']
-    if not re.match(name_regex, name):
-        raise InvalidTagNameError('Name must satisfy regex %r.' % name_regex)
-
-def _get_plain_names(tag):
-    return [tag_name.name for tag_name in tag.names]
-
-def _lower_list(names):
-    return [name.lower() for name in names]
-
-def _check_name_intersection(names1, names2):
-    return len(set(_lower_list(names1)).intersection(_lower_list(names2))) > 0
-
 def export_to_json():
     output = {
         'tags': [],
@@ -90,12 +78,18 @@ def export_to_json():
     with open(export_path, 'w') as handle:
         handle.write(json.dumps(output, separators=(',', ':')))
 
-def get_tag_by_name(name):
+def try_get_tag_by_name(name):
     return db.session \
         .query(db.Tag) \
         .join(db.TagName) \
         .filter(db.TagName.name.ilike(name)) \
-        .first()
+        .one_or_none()
+
+def get_tag_by_name(name):
+    tag = try_get_tag_by_name(name)
+    if not tag:
+        raise TagNotFoundError('Tag %r not found.' % name)
+    return tag
 
 def get_tags_by_names(names):
     names = util.icase_unique(names)
diff --git a/server/szurubooru/func/users.py b/server/szurubooru/func/users.py
index 85272ff..5a41881 100644
--- a/server/szurubooru/func/users.py
+++ b/server/szurubooru/func/users.py
@@ -44,19 +44,31 @@ def serialize_user(user, authenticated_user):
 def get_user_count():
     return db.session.query(db.User).count()
 
-def get_user_by_name(name):
+def try_get_user_by_name(name):
     return db.session \
         .query(db.User) \
         .filter(func.lower(db.User.name) == func.lower(name)) \
-        .first()
+        .one_or_none()
 
-def get_user_by_name_or_email(name_or_email):
+def get_user_by_name(name):
+    user = try_get_user_by_name(name)
+    if not user:
+        raise UserNotFoundError('User %r not found.' % name)
+    return user
+
+def try_get_user_by_name_or_email(name_or_email):
     return db.session \
         .query(db.User) \
         .filter(
             (func.lower(db.User.name) == func.lower(name_or_email))
             | (func.lower(db.User.email) == func.lower(name_or_email))) \
-        .first()
+        .one_or_none()
+
+def get_user_by_name_or_email(name_or_email):
+    user = try_get_user_by_name_or_email(name_or_email)
+    if not user:
+        raise UserNotFoundError('User %r not found.' % name_or_email)
+    return user
 
 def create_user(name, password, email, auth_user):
     user = db.User()
@@ -76,7 +88,7 @@ def update_name(user, name, auth_user):
         raise InvalidUserNameError('Name cannot be empty.')
     if util.value_exceeds_column_size(name, db.User.name):
         raise InvalidUserNameError('User name is too long.')
-    other_user = get_user_by_name(name)
+    other_user = try_get_user_by_name(name)
     if other_user and other_user.user_id != auth_user.user_id:
         raise UserAlreadyExistsError('User %r already exists.' % name)
     name = name.strip()
diff --git a/server/szurubooru/tests/api/test_post_featuring.py b/server/szurubooru/tests/api/test_post_featuring.py
index 9bb751b..a7cc24a 100644
--- a/server/szurubooru/tests/api/test_post_featuring.py
+++ b/server/szurubooru/tests/api/test_post_featuring.py
@@ -20,7 +20,7 @@ def test_ctx(context_factory, config_injector, user_factory, post_factory):
     return ret
 
 def test_no_featured_post(test_ctx):
-    assert posts.get_featured_post() is None
+    assert posts.try_get_featured_post() is None
     result = test_ctx.api.get(
         test_ctx.context_factory(
             user=test_ctx.user_factory(rank='regular_user')))
@@ -34,8 +34,8 @@ def test_featuring(test_ctx):
         test_ctx.context_factory(
             input={'id': 1},
             user=test_ctx.user_factory(rank='regular_user')))
-    assert posts.get_featured_post() is not None
-    assert posts.get_featured_post().post_id == 1
+    assert posts.try_get_featured_post() is not None
+    assert posts.try_get_featured_post().post_id == 1
     assert posts.get_post_by_id(1).is_featured
     assert 'post' in result
     assert 'snapshots' in result
@@ -63,7 +63,7 @@ def test_featuring_one_post_after_another(test_ctx, fake_datetime):
     db.session.add(test_ctx.post_factory(id=1))
     db.session.add(test_ctx.post_factory(id=2))
     db.session.commit()
-    assert posts.get_featured_post() is None
+    assert posts.try_get_featured_post() is None
     assert not posts.get_post_by_id(1).is_featured
     assert not posts.get_post_by_id(2).is_featured
     with fake_datetime('1997'):
@@ -76,8 +76,8 @@ def test_featuring_one_post_after_another(test_ctx, fake_datetime):
             test_ctx.context_factory(
                 input={'id': 2},
                 user=test_ctx.user_factory(rank='regular_user')))
-    assert posts.get_featured_post() is not None
-    assert posts.get_featured_post().post_id == 2
+    assert posts.try_get_featured_post() is not None
+    assert posts.try_get_featured_post().post_id == 2
     assert not posts.get_post_by_id(1).is_featured
     assert posts.get_post_by_id(2).is_featured
 
diff --git a/server/szurubooru/tests/api/test_tag_category_updating.py b/server/szurubooru/tests/api/test_tag_category_updating.py
index 3924c7f..592cdd4 100644
--- a/server/szurubooru/tests/api/test_tag_category_updating.py
+++ b/server/szurubooru/tests/api/test_tag_category_updating.py
@@ -43,7 +43,7 @@ def test_simple_updating(test_ctx):
         'color': 'white',
     }
     assert len(result['snapshots']) == 1
-    assert tag_categories.get_category_by_name('name') is None
+    assert tag_categories.try_get_category_by_name('name') is None
     category = tag_categories.get_category_by_name('changed')
     assert category is not None
     assert category.name == 'changed'
diff --git a/server/szurubooru/tests/api/test_tag_creating.py b/server/szurubooru/tests/api/test_tag_creating.py
index 5061d07..5f4b6fe 100644
--- a/server/szurubooru/tests/api/test_tag_creating.py
+++ b/server/szurubooru/tests/api/test_tag_creating.py
@@ -4,13 +4,6 @@ import pytest
 from szurubooru import api, config, db, errors
 from szurubooru.func import util, tags
 
-def get_tag(name):
-    return db.session \
-        .query(db.Tag) \
-        .join(db.TagName) \
-        .filter(db.TagName.name==name) \
-        .first()
-
 def assert_relations(relations, expected_tag_names):
     actual_names = [rel.names[0].name for rel in relations]
     assert actual_names == expected_tag_names
@@ -54,7 +47,7 @@ def test_creating_simple_tags(test_ctx, fake_datetime):
         'lastEditTime': None,
     }
     assert len(result['snapshots']) == 1
-    tag = get_tag('tag1')
+    tag = tags.get_tag_by_name('tag1')
     assert [tag_name.name for tag_name in tag.names] == ['tag1', 'tag2']
     assert tag.category.name == 'meta'
     assert tag.last_edit_time is None
@@ -133,7 +126,7 @@ def test_duplicating_names(test_ctx):
             user=test_ctx.user_factory(rank='regular_user')))
     assert result['tag']['names'] == ['tag1']
     assert result['tag']['category'] == 'meta'
-    tag = get_tag('tag1')
+    tag = tags.get_tag_by_name('tag1')
     assert [tag_name.name for tag_name in tag.names] == ['tag1']
 
 def test_trying_to_use_existing_name(test_ctx):
@@ -162,7 +155,7 @@ def test_trying_to_use_existing_name(test_ctx):
                     'implications': [],
                 },
                 user=test_ctx.user_factory(rank='regular_user')))
-    assert get_tag('unused') is None
+    assert tags.try_get_tag_by_name('unused') is None
 
 @pytest.mark.parametrize('input,expected_suggestions,expected_implications', [
     # new relations
@@ -201,11 +194,11 @@ def test_creating_new_suggestions_and_implications(
             input=input, user=test_ctx.user_factory(rank='regular_user')))
     assert result['tag']['suggestions'] == expected_suggestions
     assert result['tag']['implications'] == expected_implications
-    tag = get_tag('main')
+    tag = tags.get_tag_by_name('main')
     assert_relations(tag.suggestions, expected_suggestions)
     assert_relations(tag.implications, expected_implications)
     for name in ['main'] + expected_suggestions + expected_implications:
-        assert get_tag(name) is not None
+        assert tags.try_get_tag_by_name(name) is not None
 
 def test_reusing_suggestions_and_implications(test_ctx):
     db.session.add_all([
@@ -225,7 +218,7 @@ def test_reusing_suggestions_and_implications(test_ctx):
     # NOTE: it should export only the first name
     assert result['tag']['suggestions'] == ['tag1']
     assert result['tag']['implications'] == ['tag1']
-    tag = get_tag('new')
+    tag = tags.get_tag_by_name('new')
     assert_relations(tag.suggestions, ['tag1'])
     assert_relations(tag.implications, ['tag1'])
 
@@ -249,7 +242,7 @@ def test_tag_trying_to_relate_to_itself(test_ctx, input):
             test_ctx.context_factory(
                 input=input,
                 user=test_ctx.user_factory(rank='regular_user')))
-    assert get_tag('tag') is None
+    assert tags.try_get_tag_by_name('tag') is None
 
 def test_trying_to_create_tag_without_privileges(test_ctx):
     with pytest.raises(errors.AuthError):
diff --git a/server/szurubooru/tests/api/test_tag_merging.py b/server/szurubooru/tests/api/test_tag_merging.py
index e6dc098..2d7a2b6 100644
--- a/server/szurubooru/tests/api/test_tag_merging.py
+++ b/server/szurubooru/tests/api/test_tag_merging.py
@@ -4,13 +4,6 @@ import pytest
 from szurubooru import api, config, db, errors
 from szurubooru.func import util, tags
 
-def get_tag(name):
-    return db.session \
-        .query(db.Tag) \
-        .join(db.TagName) \
-        .filter(db.TagName.name==name) \
-        .first()
-
 @pytest.fixture
 def test_ctx(
         tmpdir, config_injector, context_factory, user_factory, tag_factory):
@@ -50,8 +43,8 @@ def test_merging_without_usages(test_ctx, fake_datetime):
         'lastEditTime': None,
     }
     assert 'snapshots' in result
-    assert get_tag('source') is None
-    tag = get_tag('target')
+    assert tags.try_get_tag_by_name('source') is None
+    tag = tags.get_tag_by_name('target')
     assert tag is not None
     assert os.path.exists(os.path.join(config.config['data_dir'], 'tags.json'))
 
@@ -76,8 +69,8 @@ def test_merging_with_usages(test_ctx, fake_datetime, post_factory):
                     'merge-to': 'target',
                 },
                 user=test_ctx.user_factory(rank='regular_user')))
-    assert get_tag('source') is None
-    assert get_tag('target').post_count == 1
+    assert tags.try_get_tag_by_name('source') is None
+    assert tags.get_tag_by_name('target').post_count == 1
 
 @pytest.mark.parametrize('input,expected_exception', [
     ({'remove': None}, tags.TagNotFoundError),
diff --git a/server/szurubooru/tests/api/test_tag_updating.py b/server/szurubooru/tests/api/test_tag_updating.py
index 282062b..f833399 100644
--- a/server/szurubooru/tests/api/test_tag_updating.py
+++ b/server/szurubooru/tests/api/test_tag_updating.py
@@ -4,13 +4,6 @@ import pytest
 from szurubooru import api, config, db, errors
 from szurubooru.func import util, tags
 
-def get_tag(name):
-    return db.session \
-        .query(db.Tag) \
-        .join(db.TagName) \
-        .filter(db.TagName.name==name) \
-        .first()
-
 def assert_relations(relations, expected_tag_names):
     actual_names = [rel.names[0].name for rel in relations]
     assert actual_names == expected_tag_names
@@ -61,9 +54,9 @@ def test_simple_updating(test_ctx, fake_datetime):
         'lastEditTime': datetime.datetime(1997, 12, 1),
     }
     assert len(result['snapshots']) == 1
-    assert get_tag('tag1') is None
-    assert get_tag('tag2') is None
-    tag = get_tag('tag3')
+    assert tags.try_get_tag_by_name('tag1') is None
+    assert tags.try_get_tag_by_name('tag2') is None
+    tag = tags.get_tag_by_name('tag3')
     assert tag is not None
     assert [tag_name.name for tag_name in tag.names] == ['tag3']
     assert tag.category.name == 'character'
@@ -132,9 +125,9 @@ def test_reusing_own_name(test_ctx, dup_name):
             user=test_ctx.user_factory(rank='regular_user')),
         'tag1')
     assert result['tag']['names'] == ['tag1', 'tag3']
-    assert get_tag('tag2') is None
-    tag1 = get_tag('tag1')
-    tag2 = get_tag('tag3')
+    assert tags.try_get_tag_by_name('tag2') is None
+    tag1 = tags.get_tag_by_name('tag1')
+    tag2 = tags.get_tag_by_name('tag3')
     assert tag1.tag_id == tag2.tag_id
     assert [name.name for name in tag1.names] == ['tag1', 'tag3']
 
@@ -147,9 +140,9 @@ def test_duplicating_names(test_ctx):
             user=test_ctx.user_factory(rank='regular_user')),
         'tag1')
     assert result['tag']['names'] == ['tag3']
-    assert get_tag('tag1') is None
-    assert get_tag('tag2') is None
-    tag = get_tag('tag3')
+    assert tags.try_get_tag_by_name('tag1') is None
+    assert tags.try_get_tag_by_name('tag2') is None
+    tag = tags.get_tag_by_name('tag3')
     assert tag is not None
     assert [tag_name.name for tag_name in tag.names] == ['tag3']
 
@@ -199,11 +192,11 @@ def test_updating_new_suggestions_and_implications(
         'main')
     assert result['tag']['suggestions'] == expected_suggestions
     assert result['tag']['implications'] == expected_implications
-    tag = get_tag('main')
+    tag = tags.get_tag_by_name('main')
     assert_relations(tag.suggestions, expected_suggestions)
     assert_relations(tag.implications, expected_implications)
     for name in ['main'] + expected_suggestions + expected_implications:
-        assert get_tag(name) is not None
+        assert tags.try_get_tag_by_name(name) is not None
 
 def test_reusing_suggestions_and_implications(test_ctx):
     db.session.add_all([
@@ -225,7 +218,7 @@ def test_reusing_suggestions_and_implications(test_ctx):
     # NOTE: it should export only the first name
     assert result['tag']['suggestions'] == ['tag1']
     assert result['tag']['implications'] == ['tag1']
-    tag = get_tag('new')
+    tag = tags.get_tag_by_name('new')
     assert_relations(tag.suggestions, ['tag1'])
     assert_relations(tag.implications, ['tag1'])
 
diff --git a/server/szurubooru/tests/api/test_user_creating.py b/server/szurubooru/tests/api/test_user_creating.py
index 274f0f4..3bb18ff 100644
--- a/server/szurubooru/tests/api/test_user_creating.py
+++ b/server/szurubooru/tests/api/test_user_creating.py
@@ -8,9 +8,6 @@ EMPTY_PIXEL = \
     b'\xff\xff\xff\x21\xf9\x04\x01\x00\x00\x01\x00\x2c\x00\x00\x00\x00' \
     b'\x01\x00\x01\x00\x00\x02\x02\x4c\x01\x00\x3b'
 
-def get_user(name):
-    return db.session.query(db.User).filter_by(name=name).first()
-
 @pytest.fixture
 def test_ctx(config_injector, context_factory, user_factory):
     config_injector({
@@ -51,7 +48,7 @@ def test_creating_user(test_ctx, fake_datetime):
             'rankName': 'Unknown',
         }
     }
-    user = get_user('chewie1')
+    user = users.get_user_by_name('chewie1')
     assert user.name == 'chewie1'
     assert user.email == 'asd@asd.asd'
     assert user.rank == 'admin'
@@ -77,8 +74,8 @@ def test_first_user_becomes_admin_others_not(test_ctx):
             user=test_ctx.user_factory(rank='anonymous')))
     assert result1['user']['rank'] == 'admin'
     assert result2['user']['rank'] == 'regular_user'
-    first_user = get_user('chewie1')
-    other_user = get_user('chewie2')
+    first_user = users.get_user_by_name('chewie1')
+    other_user = users.get_user_by_name('chewie2')
     assert first_user.rank == 'admin'
     assert other_user.rank == 'regular_user'
 
@@ -225,7 +222,7 @@ def test_uploading_avatar(test_ctx, tmpdir):
             },
             files={'avatar': EMPTY_PIXEL},
             user=test_ctx.user_factory(rank='mod')))
-    user = get_user('chewie')
+    user = users.get_user_by_name('chewie')
     assert user.avatar_style == user.AVATAR_MANUAL
     assert response['user']['avatarUrl'] == \
         'http://example.com/data/avatars/chewie.jpg'
diff --git a/server/szurubooru/tests/api/test_user_updating.py b/server/szurubooru/tests/api/test_user_updating.py
index e069c24..72723f4 100644
--- a/server/szurubooru/tests/api/test_user_updating.py
+++ b/server/szurubooru/tests/api/test_user_updating.py
@@ -8,9 +8,6 @@ EMPTY_PIXEL = \
     b'\xff\xff\xff\x21\xf9\x04\x01\x00\x00\x01\x00\x2c\x00\x00\x00\x00' \
     b'\x01\x00\x01\x00\x00\x02\x02\x4c\x01\x00\x3b'
 
-def get_user(name):
-    return db.session.query(db.User).filter_by(name=name).first()
-
 @pytest.fixture
 def test_ctx(config_injector, context_factory, user_factory):
     config_injector({
@@ -66,7 +63,7 @@ def test_updating_user(test_ctx):
             'rankName': 'Unknown',
         }
     }
-    user = get_user('chewie')
+    user = users.get_user_by_name('chewie')
     assert user.name == 'chewie'
     assert user.email == 'asd@asd.asd'
     assert user.rank == 'mod'
@@ -133,7 +130,7 @@ def test_removing_email(test_ctx):
     db.session.add(user)
     test_ctx.api.put(
         test_ctx.context_factory(input={'email': ''}, user=user), 'u1')
-    assert get_user('u1').email is None
+    assert users.get_user_by_name('u1').email is None
 
 @pytest.mark.parametrize('input', [
     {'name': 'whatever'},
@@ -183,7 +180,7 @@ def test_uploading_avatar(test_ctx, tmpdir):
             files={'avatar': EMPTY_PIXEL},
             user=user),
         'u1')
-    user = get_user('u1')
+    user = users.get_user_by_name('u1')
     assert user.avatar_style == user.AVATAR_MANUAL
     assert response['user']['avatarUrl'] == \
         'http://example.com/data/avatars/u1.jpg'