Merge pull request #116 from eleijonmarck/patch-3

Update current.sql with an example table

Author: benjie

@app/db/migrations/current.sql

@@ -1 +1,117 @@
--- Enter migration here
+/*
+
+This project is using Graphile Migrate to manage migrations; please be aware
+the Graphile Migrate works in a different way to most other migration
+frameworks:
+
+- it's "up-only" (there are no down migrations)
+- the current migration (this file) is executed every time it is saved
+- it requires *significant discipline* as changes made in this file will
+  persist locally even after they are deleted from the file
+
+Because during development the current migration is expected to run multiple
+times, the migration has to deal with both the situation where it _has_ been
+executed before, and where it _hasn't_ been executed before.
+
+You can (and should) read more on Graphile Migrate in its repository:
+
+  https://github.com/graphile/migrate
+
+You can absolutely switch out Graphile Migrate for a more traditional
+migration framework if you prefer.
+
+*/
+
+--------------------------------------------------------------------------------
+
+/*
+
+What follows is an example of a table that could be created after setup is
+complete. To use it uncomment the statements below and save the file -
+graphile-migrate will update the schema into database automagically and
+PostGraphile should automatically detect these changes and reflect them
+through GraphQL which you should see immediately in GraphiQL.
+
+Note any "DROP" statements should be at the top in reverse order of creation.
+The reason for reverse order is because we could have references from the
+second created resource to the first created resource. So your migration
+might look something like this pseudo-example:
+
+    DROP C;
+    DROP B;
+    DROP A;
+    CREATE A;
+    CREATE B REFERENCING A;
+    CREATE C REFERENCING A;
+
+We have to DROP B before DROP A because we have references that point to A
+from B.
+
+You can uncomment the following lines one block a time and safe the file to view
+the changes.
+
+**IMPORTANT**: when you uncomment the `CREATE TABLE` statements this will not
+result in the table being added to the GraphQL API, this is because we are
+using `ignoreRBAC: false` so we do not expose tables until you `GRANT` the
+relevant operations on them. The tables will appear when you uncomment the
+`GRANT` lines.
+
+*/
+
+-- drop table if exists app_public.user_feed_posts;
+-- drop table if exists app_public.posts;
+-- drop table if exists app_public.topics;
+
+-- create table app_public.topics (
+--   title            text not null primary key
+-- );
+-- alter table app_public.topics enable row level security;
+
+-- create table app_public.posts (
+--   id               serial primary key,
+--   author_id        int default app_public.current_user_id() references app_public.users(id) on delete set null,
+--   headline         text not null check (char_length(headline) < 280),
+--   body             text,
+--   topic            text not null references app_public.topics on delete restrict,
+--   created_at       timestamptz not null default now(),
+--   updated_at       timestamptz not null default now()
+-- );
+-- alter table app_public.posts enable row level security;
+
+-- create trigger _100_timestamps before insert or update on app_public.posts for each row execute procedure app_private.tg__timestamps();
+
+-- grant
+--   select,
+--   insert (headline, body, topic),
+--   update (headline, body, topic),
+--   delete
+-- on app_public.posts to :DATABASE_VISITOR;
+
+-- create policy select_all on app_public.posts for select using (true);
+-- create policy manage_own on app_public.posts for all using (author_id = app_public.current_user_id());
+-- create policy manage_as_admin on app_public.posts for all using (exists (select 1 from app_public.users where is_admin is true and id = app_public.current_user_id()));
+
+-- comment on table app_public.posts is 'A forum post written by a `User`.';
+-- comment on column app_public.posts.id is 'The primary key for the `Post`.';
+-- comment on column app_public.posts.headline is 'The title written by the `User`.';
+-- comment on column app_public.posts.author_id is 'The id of the author `User`.';
+-- comment on column app_public.posts.topic is 'The `Topic` this has been posted in.';
+-- comment on column app_public.posts.body is 'The main body text of our `Post`.';
+-- comment on column app_public.posts.created_at is 'The time this `Post` was created.';
+-- comment on column app_public.posts.updated_at is 'The time this `Post` was last modified (or created).';
+
+-- create table app_public.user_feed_posts (
+--   id               serial primary key,
+--   user_id          int not null references app_public.users on delete cascade,
+--   post_id          int not null references app_public.posts on delete cascade,
+--   created_at       timestamptz not null default now()
+-- );
+-- alter table app_public.user_feed_posts enable row level security;
+
+-- grant select on app_public.user_feed_posts to :DATABASE_VISITOR;
+
+-- create policy select_own on app_public.user_feed_posts for select using (user_id = app_public.current_user_id());
+
+-- comment on table app_public.user_feed_posts is 'A feed of `Post`s relevant to a particular `User`.';
+-- comment on column app_public.user_feed_posts.id is 'An identifier for this entry in the feed.';
+-- comment on column app_public.user_feed_posts.created_at is 'The time this feed item was added.';