* PERF: Remove JOIN on categories for PM search
JOIN on categories is not needed when searchin in private messages as
PMs are not categorized.
* DEV: Use == for string comparison
* PERF: Optimize query for allowed topic groups
There was a query that checked for all topics a user or their groups
were allowed to see. This used UNION between topic_allowed_users and
topic_allowed_groups which was very inefficient. That was replaced with
a OR condition that checks in either tables more efficiently.
When inviting a group to a topic, there may be members of
the group already in the topic as topic allowed users. These
can be safely removed from the topic, because they are implicitly
allowed in the topic based on their group membership.
Also, this prevents issues with group SMTP emails, which rely
on the topic_allowed_users of the topic to send to and cc's
for emails, and if there are members of the group as topic_allowed_users
then that complicates things and causes odd behaviour.
We also ensure that the OP of the topic is not removed from
the topic_allowed_users when a group they belong to is added,
as it will make it harder to add them back later.
Sometimes administrators want to permanently delete posts and topics
from the database. To make sure that this is done for a good reasons,
administrators can do this only after one minute has passed since the
post was deleted or immediately if another administrator does it.
* PERF: Improve database query perf when loading topics for a category.
Instead of left joining the `topics` table against `categories` by filtering with `categories.id`,
we can improve the query plan by filtering against `topics.category_id`
first before joining which helps to reduce the number of rows in the
topics table that has to be joined against the other tables and also
make better use of our existing index.
The following is a before and after of the query plan for a category
with many subcategories.
Before:
```
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------
Limit (cost=1.28..747.09 rows=30 width=12) (actual time=85.502..2453.727 rows=30 loops=1)
-> Nested Loop Left Join (cost=1.28..566518.36 rows=22788 width=12) (actual time=85.501..2453.722 rows=30 loops=1)
Join Filter: (category_users.category_id = topics.category_id)
Filter: ((topics.category_id = 11) OR (COALESCE(category_users.notification_level, 1) <> 0) OR (tu.notification_level > 1))
-> Nested Loop Left Join (cost=1.00..566001.58 rows=22866 width=20) (actual time=85.494..2453.702 rows=30 loops=1)
Filter: ((COALESCE(tu.notification_level, 1) > 0) AND ((topics.category_id <> 11) OR (topics.pinned_at IS NULL) OR ((t
opics.pinned_at <= tu.cleared_pinned_at) AND (tu.cleared_pinned_at IS NOT NULL))))
Rows Removed by Filter: 1
-> Nested Loop (cost=0.57..528561.75 rows=68606 width=24) (actual time=85.472..2453.562 rows=31 loops=1)
Join Filter: ((topics.category_id = categories.id) AND ((categories.topic_id <> topics.id) OR (categories.id = 1
1)))
Rows Removed by Join Filter: 13938306
-> Index Scan using index_topics_on_bumped_at on topics (cost=0.42..100480.05 rows=715549 width=24) (actual ti
me=0.010..633.015 rows=464623 loops=1)
Filter: ((deleted_at IS NULL) AND ((archetype)::text <> 'private_message'::text))
Rows Removed by Filter: 105321
-> Materialize (cost=0.14..36.04 rows=30 width=8) (actual time=0.000..0.002 rows=30 loops=464623)
-> Index Scan using categories_pkey on categories (cost=0.14..35.89 rows=30 width=8) (actual time=0.006.
.0.040 rows=30 loops=1)
Index Cond: (id = ANY ('{11,53,57,55,54,56,112,94,107,115,116,117,97,95,102,103,101,105,99,114,106,1
13,104,98,100,96,108,109,110,111}'::integer[]))
-> Index Scan using index_topic_users_on_topic_id_and_user_id on topic_users tu (cost=0.43..0.53 rows=1 width=16) (a
ctual time=0.004..0.004 rows=0 loops=31)
Index Cond: ((topic_id = topics.id) AND (user_id = 1103877))
-> Materialize (cost=0.28..2.30 rows=1 width=8) (actual time=0.000..0.000 rows=0 loops=30)
-> Index Scan using index_category_users_on_user_id_and_last_seen_at on category_users (cost=0.28..2.29 rows=1 width
=8) (actual time=0.004..0.004 rows=0 loops=1)
Index Cond: (user_id = 1103877)
Planning Time: 1.359 ms
Execution Time: 2453.765 ms
(23 rows)
```
After:
```
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=1.28..438.55 rows=30 width=12) (actual time=38.297..657.215 rows=30 loops=1)
-> Nested Loop Left Join (cost=1.28..195944.68 rows=13443 width=12) (actual time=38.296..657.211 rows=30 loops=1)
Filter: ((categories.topic_id <> topics.id) OR (topics.category_id = 11))
Rows Removed by Filter: 29
-> Nested Loop Left Join (cost=1.13..193462.59 rows=13443 width=16) (actual time=38.289..657.092 rows=59 loops=1)
Join Filter: (category_users.category_id = topics.category_id)
Filter: ((topics.category_id = 11) OR (COALESCE(category_users.notification_level, 1) <> 0) OR (tu.notification_level > 1))
-> Nested Loop Left Join (cost=0.85..193156.79 rows=13489 width=20) (actual time=38.282..657.059 rows=59 loops=1)
Filter: ((COALESCE(tu.notification_level, 1) > 0) AND ((topics.category_id <> 11) OR (topics.pinned_at IS NULL) OR ((topics.pinned_at <= tu.cleared_pinned_at) AND (tu.cleared_pinned_at IS NOT NULL))))
Rows Removed by Filter: 1
-> Index Scan using index_topics_on_bumped_at on topics (cost=0.42..134521.06 rows=40470 width=24) (actual time=38.267..656.850 rows=60 loops=1)
Filter: ((deleted_at IS NULL) AND ((archetype)::text <> 'private_message'::text) AND (category_id = ANY ('{11,53,57,55,54,56,112,94,107,115,116,117,97,95,102,103,101,105,99,114,106,113,104,98,100,96,108,109,110,111}'::integer[])))
Rows Removed by Filter: 569895
-> Index Scan using index_topic_users_on_topic_id_and_user_id on topic_users tu (cost=0.43..1.43 rows=1 width=16) (actual time=0.003..0.003 rows=0 loops=60)
Index Cond: ((topic_id = topics.id) AND (user_id = 1103877))
-> Materialize (cost=0.28..2.30 rows=1 width=8) (actual time=0.000..0.000 rows=0 loops=59)
-> Index Scan using index_category_users_on_user_id_and_last_seen_at on category_users (cost=0.28..2.29 rows=1 width=8) (actual time=0.004..0.004 rows=0 loops=1)
Index Cond: (user_id = 1103877)
-> Index Scan using categories_pkey on categories (cost=0.14..0.17 rows=1 width=8) (actual time=0.001..0.001 rows=1 loops=59)
Index Cond: (id = topics.category_id)
Planning Time: 1.633 ms
Execution Time: 657.255 ms
(22 rows)
```
* PERF: Optimize index on topics bumped_at.
Replace `index_topics_on_bumped_at` index with a partial index on `Topic#bumped_at` filtered by archetype since there is already another index that covers private topics.
We don't need no stinkin' denormalization! This commit ignores
the topic_id column on bookmarks, to be deleted at a later date.
We don't really need this column and it's better to rely on the
post.topic_id as the canonical topic_id for bookmarks, then we
don't need to remember to update both columns if the bookmarked
post moves to another topic.
This reverts a part of changes introduced by https://github.com/discourse/discourse/pull/13947
In that PR I:
1. Disallowed topic feature links for TL-0 users
2. Additionally, disallowed just putting any URL in topic titles for TL-0 users
Actually, we don't need the second part. It introduced unnecessary complexity for no good reason. In fact, it tries to do the job that anti-spam plugins (like Akismet plugin) should be doing.
This PR reverts this second change.
This disallows putting URLs in topic titles for TL0 users, which means that:
If a TL-0 user puts a link into the title, a topic featured link won't be generated (as if it was disabled in the site settings)
Server methods for creating and updating topics will be refusing featured links when they are called by TL-0 users
TL-0 users won't be able to put any link into the topic title. For example, the title "Hey, take a look at https://my-site.com" will be rejected.
Also, it improves a bit server behavior when creating or updating feature links on topics in the categories with disabled featured links. Before the server just silently ignored a featured link field that was passed to him, now it will be returning 422 response.
When configured, all topics in the category inherits the slow mode
duration from the category's default.
Note that currently there is no way to remove the slow mode from the
topics once it has been set.
The duration column has been ignored since the commit
4af77f1e38
for topic_timers, we use duration_minutes instead.
Also removing the duration key from Topic.set_or_create_timer. The only
plugin to use this was discourse-solved, which doesn't use it any
longer
since
c722b94a97
ATM it only implements server side of it, as my need is for automation purposes. However it should probably be added in the UI too as it's unexpected to have pinned_until and no bannered_until.
This PR changes the `UserNotification` class to send outbound `user_private_message` using the group's SMTP settings, but only if:
* The first allowed_group on the topic has SMTP configured and enabled
* SiteSetting.enable_smtp is true
* The group does not have IMAP enabled, if this is enabled the `GroupSMTPMailer` handles things
The email is sent using the group's `email_username` as both the `from` and `reply-to` address, so when the user replies from their email it will go through the group's SMTP inbox, which needs to have email forwarding set up to send the message on to a location (such as a hosted site email address like meta@discoursemail.com) where it can be POSTed into discourse's handle_mail route.
Also includes a fix to `EmailReceiver#group_incoming_emails_regex` to include the `group.email_username` so the group does not get a staged user created and invited to the topic (which was a problem for IMAP), as well as updating `Group.find_by_email` to find using the `email_username` as well for inbound emails with that as the TO address.
#### Note
This is safe to merge without impacting anyone seriously. If people had SMTP enabled for a group they would have IMAP enabled too currently, and that is a very small amount of users because IMAP is an alpha product, and also because the UserNotification change has a guard to make sure it is not used if IMAP is enabled for the group. The existing IMAP tests work, and I tested this functionality by manually POSTing replies to the SMTP address into my local discourse.
There will probably be more work needed on this, but it needs to be tested further in a real hosted environment to continue.
If reload a page after enabling slow mode and open the slow mode dialog again it would show a slow mode interval but wouldn't show Enabled Until value. This PR fixes it.
The old share modal used to host both share and invite functionality,
under two tabs. The new "Share Topic" modal can be used only for
sharing, but has a link to the invite modal.
Among the sharing methods, there is also "Notify" which points out
that existing users will simply be notified (this was not clear
before). Staff members can notify as many users as they want, but
regular users are restricted to one at a time, no more than
max_topic_invitations_per_day. The user will not receive another
notification if they have been notified of the same topic in past hour.
The "Create Invite" modal also suffered some changes: the two radio
boxes for selecting the type (invite or email) have been replaced by a
single checkbox (is email?) and then the two labels about emails have
been replaced by a single one, some fields were reordered and the
advanced options toggle was moved to the bottom right of the modal.
This PR adds a new category setting which is a column in the `categories` table, `allow_unlimited_owner_edits_on_first_post`.
What this does is:
* Inside the `can_edit_post?` method of `PostGuardian`, if the current user editing a post is the owner of the post, it is the first post, and the topic's category has `allow_unlimited_owner_edits_on_first_post`, then we bypass the check for `LimitedEdit#edit_time_limit_expired?` on that post.
* Also, similar to wiki topics, in `PostActionNotifier#after_create_post_revision` we send a notification to all users watching a topic when the OP is edited in a topic with the category setting `allow_unlimited_owner_edits_on_first_post` enabled.
This is useful for forums where there is a Marketplace or similar category, where topics are created and then updated indefinitely by the OP rather than the OP making new topics or additional replies. In a way this acts similar to a wiki that only one person can edit.
It was used both when inviting from a topic page and when creating
invites with "Send to topic on first login", while it should be used
only in the former case.
The user interface has been reorganized to show email and link invites
in the same screen. Staff has more control over creating and updating
invites. Bulk invite has also been improved with better explanations.
On the server side, many code paths for email and link invites have
been merged to avoid duplicated logic. The API returns better responses
with more appropriate HTTP status codes.
When `PostCreator` creates a new topic it loads the `allowed_groups` of the topic. `Fabricate` doesn't do that and that's why the existing spec worked even though it should have failed, because `PostAlerter#notify_group_summary` didn't create a notification for a non-fabricated topic.
`Topic#invite_group` added a new `TopicAllowedGroup` record without reloading `Topic.allowed_groups`. A subsequent call to `PostAlerter#notify_group_summary` didn't work because it didn't find the invited group in the topic's `allowed_groups` association.
though other participants are not in allowed list)
If you create an allowlist of users who can PM you, and use the function
“Only specific users can send me private messages”, then you can’t be
added to group messages unless everyone in that message is already in
your allow list.
This commit allows user to be added to a group message even when other
participants are not in allowed list
Previously when inheriting category auto-close settings for a topic, those settings were disrupted if another topic timer was assigned or if a topic was closed then manually re-opened.
This PR makes it so that when a topic is manually re-opened the topic auto-close settings are inherited from the category. However, they will now be based on the topic created_at date. As an example, for a topic with a category auto close hours setting of 72 (3 days):
* Topic was created on 2021-02-15 08:00
* Topic was closed on 2021-02-16 10:00
* Topic was opened again on 2021-02-17 06:00
Now, the topic will inherit the auto close timer again and will close automatically at **2021-02-18 08:00**, which is based on the creation date. If the current date and time is greater than the original auto-close time (e.g. we were at 2021-02-20 13:45) then no auto-close timer is created.
Note, this will not happen if the topic category auto-close setting is "based on last post".
Updating a topic's visibility did not increase or decrease the
topic_count of a category, but Category.update_stats does ignore
unlisted topics which resulted in inconsistencies when deleting
such topics.
This PR allows entering a float value for topic timers e.g. 0.5 for 30 minutes when entering hours, 0.5 for 12 hours when entering days. This is achieved by adding a new column to store the duration of a topic timer in minutes instead of the ambiguous both hours and days that it could be before.
This PR has ommitted the post migration to delete the duration column in topic timers; it will be done in a subsequent PR to ensure that no data is lost if the UPDATE query to set duration_mintues fails.
I have to keep the old keyword of duration in set_or_create_topic_timer for backwards compat, will remove at a later date after plugins are updated.
This is a try to simplify logic around dismiss new topics to have one solution to work in all places - dismiss all-new, dismiss new in a specific category or even in a specific tag.
This PR adds security_last_changed_at and security_last_changed_reason to uploads. This has been done to make it easier to track down why an upload's secure column has changed and when. This necessitated a refactor of the UploadSecurity class to provide reasons why the upload security would have changed.
As well as this, a source is now provided from the location which called for the upload's security status to be updated as they are several (e.g. post creator, topic security updater, rake tasks, manual change).
Moves the topic timer jobs from being scheduled ahead of time with enqueue_at to a 5 minute scheduled run like bookmark reminders, in a new job called Jobs::EnqueueTopicTimers. Backwards compatibility is maintained by checking if an existing topic timer job is enqueued in sidekiq for the timer, and if it is not running it inside the new job.
The functionality to close/open a topic if it is in the opposite state still remains in the after_save block of TopicTimer, with further commentary, which is used for Open/Close Temporarily.
This also removes the ensure_consistency! functionality of topic timers as it is no longer needed; the new job will always pick up the timers because they are not stored in a fragile state of sidekiq.
This PR fixes a race condition with the IMAP notification code. In the `Email::Receiver` we call the `NewPostManager` to create the post and enqueue jobs and sends alerts via `PostAlerter`. However, if the post alerter reaches the `notify_pm_users` and the `group_notifying_via_smtp` method _before_ the incoming email is updated with the post and topic, we unnecessarily send a notification to the person who just posted. The result of this is that the IMAP syncer re-imports the email sent to the user about their own post, which looks like this in the group inbox:
To fix this, we skip the jobs enqueued by `NewPostManager` and only enqueue them with `PostJobsEnqueuer` manually _after_ the incoming email record has been updated with the post and topic.
Other improvements:
* Moved code to calculate email addresses from `IncomingEmail` records into the topic, with a group passed in, for easier testing and debugging. It is not the responsibility of the post alerter to figure this stuff out.
* Add shortcut methods on `IncomingEmail` to split or provide an empty array for to and cc addresses to avoid repetition.
Splits the `ToggleTopicClosed` job into two distinct `OpenTopic` and `CloseTopic` jobs to make the code clearer. The old job cannot be deleted yet because of outstanding sidekiq schedules, so a todo has been added to do so later this year.
Also replaced mentions of `topic_status_update` with `topic_timer` in some files, because the `topic_status_update` model is obsolete and replaced by topic timer.
Added some shortcut methods for checking if a topic is open/whether a user can change an open topic.
- Only initialize the S3Helper when needed
- Skip initializing the S3Helper for S3Store#cdn_url
- Allow cook_url to be passed a `local` hint to skip unnecessary checks
It used to simply say "not allowed" without giving any hint what the
problem could be. This commit refactors the code and tries to improve
readability.
This commit adds a site setting `auto_close_topics_create_linked_topic`
which when enabled works in conjunction with `auto_close_topics_post_count`
setting and creates a new linked topic for the topic just closed.
The auto-created new topic contains a link for all the previous topics
and the topic titles are appended with `(Part {n})`.
The setting is enabled by default.
Adds a new slow mode for topics that are heating up. Users will have to wait for a period of time before being able to post again.
We store this interval inside the topics table and track the last time a user posted using the last_posted_at datetime in the TopicUser relation.
DEV: Replace instances of Discourse.base_uri with Discourse.base_path
This is clearer because the base_uri is actually just a path prefix. This continues the work started in 555f467.
This PR removes the user reminder topic timers, because that system has been supplanted and improved by bookmark reminders. The option is removed from the UI and all existing user reminder topic timers are migrated to bookmark reminders.
Migration does this:
* Get all topic_timers with status_type 5 (reminders)
* Gets all bookmarks where the user ID and topic ID match
* Loops through the found topic timers
* If there is no bookmark for the OP of the topic, then we just create a bookmark with a reminder
* If there is a bookmark for the OP of the topic and it does **not** have a reminder set, then just
update it with the topic timer reminder
* If there is a bookmark for the OP of the topic with a reminder then just discard the topic timer
* Cancels all outstanding user reminder topic timers
* **Trashes (not deletes) all user reminder topic timers**
Notes:
* For now I have left the user reminder topic timer job class in place; this is so the jobs can be cancelled in the migration. It and the specs will be deleted in the next PR.
* At a later date I will write a migration to delete all trashed user topic timers. They are not deleted here in case there are data issues and they need to be recovered.
* A future PR will change the UI of the topic timer modal to make it look more like the bookmark modal.
It's possible that the original topic image is broken in some form, so
we shouldn't try and generate a topic thumbnail for it. The fix will
prevent the generate_topic_thumbnails job being enqueued every time the
topic is viewed.
* DEV: Show message when cannot invite user to PM
When inviting a user to a PM return a message that says, "Sorry, this
user can't be invited." if they have been muted or are not in a users
allowed pm users list.
* Minor refactor & improved some text
This changes PG text search to only match the given title against
lexemes that are formed from the title. Likewise, the given raw will
only be matched against lexemes that are formed from the post's raw.
It's possible through an import or other means to have images larger
than the current max allowed image size in the db.
If this happens the thumbnail generation job will keep running
indefinitely trying to download a new copy of the original but
discarding it because it is larger than the max_file_size eventually
causing this error
`Job exception: undefined method `path' for nil:NilClass`
because the newly downloaded image is now nil.
This fix stops the enqueuing of the `GenerateTopicThumbnails` job for
all images that happen to be larger than the max image size.
If any value, including nil, is passed in as an argument the default
won't be set, so we need to handle when a non-Array value is passed in
to the `generate_thumbnails!` method.
This reverts commit 20780a1eee.
* SECURITY: re-adds accidentally reverted commit:
03d26cd6: ensure embed_url contains valid http(s) uri
* when the merge commit e62a85cf was reverted, git chose the 2660c2e2 parent to land on
instead of the 03d26cd6 parent (which contains security fixes)
* We now have a site setting "topic_excerpt_maxlength" that is used when the OP is created or revised to generate a topic excerpt.
* However, posts created before this setting was introduced cannot benefit from this change unless they are revised, and if the topic excerpt length setting is changed that situation is also not covererd.
* This PR makes a change to rebake! to update the topic excerpt IF the post is the OP.
If image uploads are missing a width/height, we re-download them to update the width/height in the database. However, this takes significant resources so we don't want to run this logic during topic serialization.
This introduces new APIs for obtaining optimized thumbnails for topics. There are a few building blocks required for this:
- Introduces new `image_upload_id` columns on the `posts` and `topics` table. This replaces the old `image_url` column, which means that thumbnails are now restricted to uploads. Hotlinked thumbnails are no longer possible. In normal use (with pull_hotlinked_images enabled), this has no noticeable impact
- A migration attempts to match existing urls to upload records. If a match cannot be found then the posts will be queued for rebake
- Optimized thumbnails are generated during post_process_cooked. If thumbnails are missing when serializing a topic list, then a sidekiq job is queued
- Topic lists and topics now include a `thumbnails` key, which includes all the available images:
```
"thumbnails": [
{
"max_width": null,
"max_height": null,
"url": "//example.com/original-image.png",
"width": 1380,
"height": 1840
},
{
"max_width": 1024,
"max_height": 1024,
"url": "//example.com/optimized-image.png",
"width": 768,
"height": 1024
}
]
```
- Themes can request additional thumbnail sizes by using a modifier in their `about.json` file:
```
"modifiers": {
"topic_thumbnail_sizes": [
[200, 200],
[800, 800]
],
...
```
Remember that these are generated asynchronously, so your theme should include logic to fallback to other available thumbnails if your requested size has not yet been generated
- Two new raw plugin outlets are introduced, to improve the customisability of the topic list. `topic-list-before-columns` and `topic-list-before-link`
We have the `# frozen_string_literal: true` comment on all our
files. This means all string literals are frozen. There is no need
to call #freeze on any literals.
For files with `# frozen_string_literal: true`
```
puts %w{a b}[0].frozen?
=> true
puts "hi".frozen?
=> true
puts "a #{1} b".frozen?
=> true
puts ("a " + "b").frozen?
=> false
puts (-("a " + "b")).frozen?
=> true
```
For more details see: https://samsaffron.com/archive/2018/02/16/reducing-string-duplication-in-ruby
avg_time on posts and topics have not been used in a year.
This uses a re-runnable ddl transaction diasabled migration to
drop the column, cause it touchs very high traffic table and may
deadlock
If the feature is enabled, staff members can construct a URL and publish a
topic for others to browse without the regular Discourse chrome.
This is useful if you want to use Discourse like a CMS and publish
topics as articles, which can then be embedded into other systems.
New `duration` attribute is introduced for the `set_or_create_timer` method in the commit aad12822b7 for "based on last post" and "auto delete replies" topic timers.
### UI Changes
If `SiteSetting.enable_bookmarks_with_reminders` is enabled:
* Clicking "Bookmark" on a topic will create a new Bookmark record instead of a post + user action
* Clicking "Clear Bookmarks" on a topic will delete all the new Bookmark records on a topic
* The topic bookmark buttons control the post bookmark flags correctly and vice-versa
Disabled selecting the "reminder type" for bookmarks in the UI because the backend functionality is not done yet (of sending users notifications etc.)
### Other Changes
* Added delete bookmark route (but no UI yet)
* Added a rake task to sync the old PostAction bookmarks to the new Bookmark table, which can be run as many times as we want for a site (it will not create duplicates).
Add TopicUploadSecurityManager to handle post moves. When a post moves around or a topic changes between categories and public/private message status the uploads connected to posts in the topic need to have their secure status updated, depending on the security context the topic now lives in.
The following methods have long been deprecated in ruby due to flaws in their implementation per http://blade.nagaokaut.ac.jp/cgi-bin/vframe.rb/ruby/ruby-core/29293?29179-31097:
URI.escape
URI.unescape
URI.encode
URI.unencode
escape/encode are just aliases for one another. This PR uses the Addressable gem to replace these methods with its own encode, unencode, and encode_component methods where appropriate.
I have put all references to Addressable::URI here into the UrlHelper to keep them corralled in one place to make changes to this implementation easier.
Addressable is now also an explicit gem dependency.
This ensures we can very quickly figure out which topics are banners if
a banner is set.
Previously you would have to scan an entire table to find banners
Doing .pluck(:column).first is a very common pattern in Discourse and in
most cases, a limit cause isn't being added. Instead of adding a limit
clause to all these callsites, this commit adds two new methods to
ActiveRecord::Relation:
pluck_first, equivalent to limit(1).pluck(*columns).first
and pluck_first! which, like other finder methods, raises an exception
when no record is found
