Added first draft of versions to schema

pull/3/head
Jef Roosens 2021-12-23 16:28:43 +01:00
parent b83ea9796b
commit fb38a1c1bf
Signed by: Jef Roosens
GPG Key ID: 955C0660072F691F
4 changed files with 107 additions and 27 deletions

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@ -1,3 +1,38 @@
# blog # blog
Handles the contents of the blogging section. Handles the contents of the blogging section.
## Schema & Data Objects
All objects have a personal UUID ID, generated automatically by PostgreSQL.
### Sections
Sections group posts according to a common subject or some other metric by
which they could be grouped. They can be seen as sub-blogs within the larger
system. Each post can be part of only one section, & posts not part of a
section will not be shown in the public UI.
A section has a title & optional description, along with a shortname. The
shortname is what will be used inside URLs for routing.
A section can be part of the default posts list, meaning all posts created in
this section will be shown on the homepage. The default list is an aggregated
list containing all default sections.
A section can be private, meaning all posts created in this section will not be
shown on the any public page without authentification. Furthermore, it can
specify wether posts should have titles, or are not allowed to. This is to
allow for creating microblogs, which do not require titles.
### Posts & Versions
A post represents a publication in a specific section. The posts table itself
only specifies which section a post belongs to & wether or not the post is
private. Any content of the actual post is stored a a version. A private post
can only be seen by logged-in users with the right authorization.
Each version has its own publication date, with the last publication being
shown when visiting the post. The UI however should also expose a way to show
previous versions of the post. Each version has its own title (if allowed) &
content. A version can be a draft. This means that the version will not be shown in the public UI, allowing the user to finish it at a later time.

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@ -1,7 +1,8 @@
-- This file should undo anything in `up.sql` -- This file should undo anything in `up.sql`
drop trigger insert_enforce_post_titles on posts; drop trigger insert_enforce_version_titles on versions;
drop trigger update_enforce_post_titles on posts; drop trigger update_enforce_version_titles on versions;
drop function enforce_post_titles; drop function enforce_version_titles;
drop table versions cascade;
drop table posts cascade; drop table posts cascade;
drop table sections cascade; drop table sections cascade;

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@ -1,4 +1,3 @@
-- Your SQL goes here
create table sections ( create table sections (
id uuid DEFAULT gen_random_uuid() PRIMARY KEY, id uuid DEFAULT gen_random_uuid() PRIMARY KEY,
@ -11,48 +10,80 @@ create table sections (
-- Wether to show the section in the default list on the homepage -- Wether to show the section in the default list on the homepage
is_default boolean NOT NULL DEFAULT false, is_default boolean NOT NULL DEFAULT false,
-- Wether the posts should contain titles or not -- Wether the posts should contain titles or not
has_titles boolean NOT NULL DEFAULT true has_titles boolean NOT NULL DEFAULT true,
-- Wether posts in this section should be shown publicly
is_private boolean NOT NULL DEFAULT false
); );
create table posts ( create table posts (
id uuid DEFAULT gen_random_uuid() PRIMARY KEY, id uuid DEFAULT gen_random_uuid() PRIMARY KEY,
section_id uuid NOT NULL REFERENCES sections(id) ON DELETE CASCADE, -- Posts shouldn't get deleted when we delete a section, as they're the
-- Title of the post -- most valuable part of a blog
-- Wether this is NULL or not is enforced using the enforce_post_titles trigger section_id uuid NOT NULL REFERENCES sections(id) ON DELETE SET NULL,
title varchar(255),
-- Post date, defaults to today -- Wether a post should be private
publish_date date NOT NULL DEFAULT now(), is_private boolean NOT NULL DEFAULT false,
-- Content of the post -- Wether the post is archived
content text NOT NULL is_archived boolean NOT NULL DEFAULT false
); );
create function enforce_post_titles() returns trigger as $enforce_post_titles$ create table versions (
id uuid DEFAULT gen_random_uuid() PRIMARY KEY,
-- A version should be deleted when its referenced post is deleted
post_id uuid NOT NULL REFERENCES posts(id) ON DELETE CASCADE,
-- Title of the post. Wether this is NULL or not is enforced using the
-- enforce_post_titles trigger.
title varchar(255),
-- Publish date
publish_date date,
-- Content of the post, in Markdown
content text NOT NULL DEFAULT '',
-- Wether the version is still a draft
is_draft boolean NOT NULL default true,
-- This check allows draft posts to be created without having to enter a
-- publish date, but forces them to have one if they're not a draft.
CHECK (is_draft OR publish_date IS NOT NULL)
);
create function enforce_version_titles() returns trigger as $$
begin begin
-- Draft versions shouldn't be evaluated.
if new.is_draft then
return new;
end if;
-- Check for a wrongfully null title -- Check for a wrongfully null title
if new.title is null and exists ( if new.title is null and exists (
select 1 from sections where id = new.section_id and has_titles select 1 from posts
inner join sections on posts.section_id = sections.id
where posts.id = new.post_id and sections.has_titles
) then ) then
raise exception 'Expected a post title, but got null.'; raise exception 'Expected a post title, but got null.';
end if; end if;
if new.title is not null and exists ( if new.title is not null and exists (
select 1 from sections where id = new.section_id and not has_titles select 1 from posts
inner join sections on posts.section_id = sections.id
where posts.id = new.post_id and not sections.has_titles
) then ) then
raise exception 'Expected an empty post title, but got a value.'; raise exception 'Expected an empty post title, but got a value.';
end if; end if;
return new; return new;
end; end;
$enforce_post_titles$ language plpgsql; $$ language plpgsql;
create trigger insert_enforce_post_titles create trigger insert_enforce_version_titles
before insert on posts before insert on versions
for each row for each row
execute function enforce_post_titles(); execute function enforce_version_titles();
create trigger update_enforce_post_titles create trigger update_enforce_version_titles
before update of title on posts before update of title on versions
for each row for each row
when (old.title is distinct from new.title) when (old.title is distinct from new.title)
execute function enforce_post_titles(); execute function enforce_version_titles();

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@ -2,9 +2,8 @@ table! {
posts (id) { posts (id) {
id -> Uuid, id -> Uuid,
section_id -> Uuid, section_id -> Uuid,
title -> Nullable<Varchar>, is_private -> Bool,
publish_date -> Date, is_archived -> Bool,
content -> Text,
} }
} }
@ -16,12 +15,26 @@ table! {
description -> Nullable<Text>, description -> Nullable<Text>,
is_default -> Bool, is_default -> Bool,
has_titles -> Bool, has_titles -> Bool,
is_private -> Bool,
}
}
table! {
versions (id) {
id -> Uuid,
post_id -> Uuid,
title -> Nullable<Varchar>,
publish_date -> Nullable<Date>,
content -> Text,
is_draft -> Bool,
} }
} }
joinable!(posts -> sections (section_id)); joinable!(posts -> sections (section_id));
joinable!(versions -> posts (post_id));
allow_tables_to_appear_in_same_query!( allow_tables_to_appear_in_same_query!(
posts, posts,
sections, sections,
versions,
); );