Firebase 產品的開源替代品
但是等等，如果他們已經有了函數為什麼還需要邊緣函數？
Supabase 函數：您的 PostgreSQL 工具箱
Supabase 函數，也稱為資料庫函數，本質上是 PostgreSQL 預存程序。它們是可執行的 SQL 程式碼區塊，可以從 SQL 查詢中呼叫。
邊緣函數：超越資料庫
相較之下，Edge 函數是在 Deno 運行時運行的伺服器端 TypeScript 函數。它們與 Firebase Cloud Functions 類似，但提供了更靈活和開源的替代方案。
Supabase：PostgreSQL 平台
除了作為 Firebase 的開源替代品之外，Supabase 已發展成為一個全面的 PostgreSQL 平台。它為 PostgreSQL 函數提供一流的支持，將它們無縫整合到其內建實用程式中，並允許您直接從 Supabase 儀表板建立和管理自訂函數。
基本 postgres 函數的結構
CREATE FUNCTION my_function() RETURNS int AS $$
BEGIN
RETURN 42;
END;
$$ LANGUAGE sql;
細分：
目的：
函數定義了一個名為 my_function 的簡單 SQL 函數，它會傳回整數值 42。這是一個示範 PostgreSQL 中函數定義的結構和語法的基本範例。
要記住的重點：
$$ 分隔符號用於以與語言無關的方式包圍函數體。
Postgres 函數也可以由 postgres TRIGGERS 調用，它們類似於函數，但對特定事件做出反應，例如表上的插入、更新或刪除
執行此函數
SELECT my_function();
SELECT
proname AS function_name,
prokind AS function_type
FROM pg_proc
WHERE proname = 'my_function';
DROP FUNCTION my_function();
內建函數
Supabase 使用 postgres 函數在資料庫中執行某些任務。
範例的簡短清單包括
-- list all the supabase functions
SELECT
proname AS function_name,
prokind AS function_type
FROM pg_proc;
-- filter for the session supabase functions function
SELECT
proname AS function_name,
prokind AS function_type
FROM pg_proc
WHERE proname ILIKE '%session%';
-- selects the curremt jwt
select auth.jwt()
-- select what role is callig the function (anon or authenticated)
select auth.role();
-- select the session user
select session_use;
儀表板上的 Supabase 功能視圖
要在 Supabase 中查看其中一些功能，您可以在資料庫 > 下查看功能
在使用者註冊時建立 user_profile 表
Supabase 將使用者資料儲存在 auth.users 表中，該表是私有的，不應直接存取或修改。建議的方法是建立一個公共 users 或 user_profiles 表並將其連結到 auth.users 表。
雖然這可以使用客戶端 SDK 透過將建立使用者請求與成功的註冊請求連結起來來完成，但在 Supabase 端處理它會更可靠、更有效率。這可以使用觸發器和函數的組合來實現。
-- create the user_profiles table
CREATE TABLE user_profiles (
id uuid PRIMARY KEY,
FOREIGN KEY (id) REFERENCES auth.users(id),
name text,
email text
);
-- create a function that returns a trigger on auth.users
CREATE
OR REPLACE FUNCTION public.create_public_user_profile_table()
RETURNS TRIGGER AS $$
BEGIN INSERT INTO public.user_profiles (id,name,email)
VALUES
(
NEW.id,
NEW.raw_user_meta_data ->> 'name',
NEW.raw_user_meta_data ->> 'email'
-- other fields accessible here
-- NEW.raw_user_meta_data ->> 'name',
-- NEW.raw_user_meta_data ->> 'picture',
);
RETURN NEW;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;
-- create the trigger that executes the function on every new user rowcteation(signup)
CREATE TRIGGER create_public_user_profiles_trigger
AFTER INSERT ON auth.users FOR EACH ROW WHEN (
NEW.raw_user_meta_data IS NOT NULL
)
EXECUTE FUNCTION public.create_public_user_profile_table ();
let { data: user_profiles, error } = await supabase
.from('user_profiles')
.select('*')
我們需要2塊
-- Custom types
create type public.app_permission as enum ('channels.delete', 'channels.update', 'messages.update', 'messages.delete');
create type public.app_role as enum ('admin', 'moderator');
-- USER ROLES
create table public.user_roles (
id bigint generated by default as identity primary key,
user_id uuid references public.users on delete cascade not null,
role app_role not null,
unique (user_id, role)
);
comment on table public.user_roles is 'Application roles for each user.';
-- ROLE PERMISSIONS
create table public.role_permissions (
id bigint generated by default as identity primary key,
role app_role not null,
permission app_permission not null,
unique (role, permission)
);
comment on table public.role_permissions is 'Application permissions for each role.';
使用者角色範例
| id | user_id | role |
|---|---|---|
| 1 | user-1 | admin |
| 2 | user-2 | moderator |
example of a role permission table
| id | role | permission |
|---|---|---|
| 1 | admin | channels.update |
| 2 | admin | messages.update |
| 3 | admin | messages.delete |
| 4 | admin | messages.delete |
| 5 | moderator | channels.update |
| 6 | moderator | messages.update |
user with user_id = user-1 will have admin and moderator roles and can delete channels and messages
users with user_id = user-2 can only update channels and messages with the moderator role
-- Create the auth hook function
create or replace function public.custom_access_token_hook(event jsonb)
returns jsonb
language plpgsql
stable
as $$
declare
claims jsonb;
user_role public.app_role;
begin
-- Fetch the user role in the user_roles table
select role into user_role from public.user_roles where user_id = (event->>'user_id')::uuid;
claims := event->'claims';
if user_role is not null then
-- Set the claim
claims := jsonb_set(claims, '{user_role}', to_jsonb(user_role));
else
claims := jsonb_set(claims, '{user_role}', 'null');
end if;
-- Update the 'claims' object in the original event
event := jsonb_set(event, '{claims}', claims);
-- Return the modified or original event
return event;
end;
$$;
grant usage on schema public to supabase_auth_admin;
grant execute
on function public.custom_access_token_hook
to supabase_auth_admin;
revoke execute
on function public.custom_access_token_hook
from authenticated, anon, public;
grant all
on table public.user_roles
to supabase_auth_admin;
revoke all
on table public.user_roles
from authenticated, anon, public;
create policy "Allow auth admin to read user roles" ON public.user_roles
as permissive for select
to supabase_auth_admin
using (true)
then create a function that will be called to authorize on RLS policies
create or replace function public.authorize(
requested_permission app_permission
)
returns boolean as $$
declare
bind_permissions int;
user_role public.app_role;
begin
-- Fetch user role once and store it to reduce number of calls
select (auth.jwt() ->> 'user_role')::public.app_role into user_role;
select count(*)
into bind_permissions
from public.role_permissions
where role_permissions.permission = requested_permission
and role_permissions.role = user_role;
return bind_permissions > 0;
end;
$$ language plpgsql stable security definer set search_path = '';
-- example RLS policies
create policy "Allow authorized delete access" on public.channels for delete using ( (SELECT authorize('channels.delete')) );
create policy "Allow authorized delete access" on public.messages for delete using ( (SELECT authorize('messages.delete')) );
Improved Text:
Creating RPC Endpoints
Supabase functions can be invoked using the rpc function. This is especially useful for writing custom SQL queries when the built-in PostgreSQL APIs are insufficient, such as calculating vector cosine similarity using pg_vector.
create or replace function match_documents (
query_embedding vector(384),
match_threshold float,
match_count int
)
returns table (
id bigint,
title text,
body text,
similarity float
)
language sql stable
as $$
select
documents.id,
documents.title,
documents.body,
1 - (documents.embedding <=> query_embedding) as similarity
from documents
where 1 - (documents.embedding <=> query_embedding) > match_threshold
order by (documents.embedding <=> query_embedding) asc
limit match_count;
$$;
and call it client side
const { data: documents } = await supabaseClient.rpc('match_documents', {
query_embedding: embedding, // Pass the embedding you want to compare
match_threshold: 0.78, // Choose an appropriate threshold for your data
match_count: 10, // Choose the number of matches
})
Improved Text:
Filtering Out Columns
To prevent certain columns from being modified on the client, create a simple function that triggers on every insert. This function can omit any extra fields the user might send in the request.
-- check if user with roles authenticated or anon submitted an updatedat column and replace it with the current time , if not (thta is an admin) allow it
CREATE
or REPLACE function public.omit_updated__at () returns trigger as
$$ BEGIN
IF auth.role() IS NOT NULL AND auth.role() IN ('anon', 'authenticated')
THEN NEW.updated_at = now();
END IF;
RETURN NEW;
END; $$ language plpgsql;
With a little experimentation, you can unlock the power of Supabase functions and their AI-powered SQL editor. This lowers the barrier to entry for the niche knowledge required to get this working.
Why choose Supabase functions?
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