feature #4: create function for follow

resources/functions/follow/follow.sql

@@ -0,0 +1,21 @@
+create or replace function follow(reference regclass, target_id uuid, citizen_id uuid) returns void
+    language plpgsql as
+$$
+declare
+    _citizen_id alias for citizen_id;
+    _target_id alias for target_id;
+begin
+    if reference = 'article'::regclass then
+        insert into follow_article (citizen_id, target_id)
+        values (_citizen_id, _target_id);
+    elseif reference = 'constitution'::regclass then
+        insert into follow_constitution (citizen_id, target_id)
+        values (_citizen_id, _target_id);
+    elseif reference = 'citizen'::regclass then
+        insert into follow_citizen (citizen_id, target_id)
+        values (_citizen_id, _target_id);
+    end if;
+end;
+$$;
+
+-- drop function if exists follow(regclass, uuid, uuid);

resources/functions/follow/unfollow.sql

@@ -0,0 +1,16 @@
+create or replace function unfollow(reference regclass, target_id uuid, citizen_id uuid) returns void
+    language plpgsql as
+$$
+declare
+    _citizen_id alias for citizen_id;
+    _target_id alias for target_id;
+begin
+    delete
+    from follow f
+    where f.citizen_id = _citizen_id
+      and f.target_id = _target_id
+      and f.target_reference = reference;
+end;
+$$;
+
+-- drop function if exists unfollow(regclass, uuid, uuid);

resources/sql/migrations/0000-init_schema.up.sql

@@ -61,14 +61,14 @@ declare
     _version_id alias for version_id;
 begin
     if (tablename = 'article'::regclass) then
-        select version_number+1
+        select version_number + 1
         into generated_number
         from article as t
         where t.version_id = _version_id
         order by version_number
         limit 1;
     elseif tablename = 'constitution'::regclass then
-        select version_number+1
+        select version_number + 1
         into generated_number
         from constitution as t
         where t.version_id = _version_id
@@ -198,6 +198,7 @@ create table follow
 
 create table follow_article
 (
+    target_reference regclass default 'article'::regclass not null,
     foreign key (citizen_id) references citizen (id),
     foreign key (target_id) references article (id),
     primary key (id)
@@ -205,6 +206,7 @@ create table follow_article
 
 create table follow_constitution
 (
+    target_reference regclass default 'constitution'::regclass not null,
     foreign key (citizen_id) references citizen (id),
     foreign key (target_id) references constitution (id),
     primary key (id)
@@ -212,6 +214,7 @@ create table follow_constitution
 
 create table follow_citizen
 (
+    target_reference regclass default 'citizen'::regclass not null,
     foreign key (citizen_id) references citizen (id),
     foreign key (target_id) references citizen (id),
     primary key (id)

resources/tests/follow.sql

@@ -0,0 +1,56 @@
+do
+$$
+declare
+    created_user     json  := '{"username": "george", "plain_password": "azerty"}';
+    created_user2    json  := '{"username": "john", "plain_password": "qwerty"}';
+    _citizen_id      uuid;
+    _citizen_id2     uuid;
+    created_citizen json := $json$
+    {
+      "name": {
+        "first_name": "George",
+        "last_name": "MICHEL"
+      },
+      "birthday": "2001-01-01"
+    }
+    $json$;
+    created_citizen2 json := $json$
+    {
+      "name": {
+        "first_name": "John",
+        "last_name": "Doe"
+      },
+      "birthday": "2002-01-01"
+    }
+    $json$;
+begin
+    -- insert user for context
+    call insert_user(created_user);
+    call insert_user(created_user2);
+    created_citizen := jsonb_set(created_citizen::jsonb, '{user}'::text[], jsonb_build_object('id', created_user->>'id'), true)::json;
+    created_citizen2 := jsonb_set(created_citizen2::jsonb, '{user}'::text[], jsonb_build_object('id', created_user2->>'id'), true)::json;
+
+    -- insert new citizen for context
+    call upsert_citizen(created_citizen);
+    _citizen_id := created_citizen->>'id';
+    -- insert new citizen for context
+    call upsert_citizen(created_citizen2);
+    _citizen_id2 := created_citizen2->>'id';
+
+
+    perform follow('citizen'::regclass, _citizen_id, _citizen_id2);
+    assert (select count(*) > 0 from follow), 'follow must be inserted';
+
+    perform unfollow('citizen'::regclass, _citizen_id, _citizen_id2);
+    assert (select count(*) = 0 from follow), 'follow must be deleted after unfollow';
+
+    -- delete article and context
+    delete from citizen;
+    delete from "user";
+
+    raise notice 'follow test pass';
+end;
+$$;
+
+
+-- select uuid_generate_v4();