How to drop a PostgreSQL database if there are active connections to it? Let's get some practice executing commands in a running docker container. Contact us. Last time we left off, we dockerized our FastAPI backend and setup a router with a single dummy endpoint. If the migration worked, we expect the cleanings table to exist and the 5 columns with the correct datatypes to be displayed in the output. Time to Read: Quick Guide to Understand Everything about Regression Testing, Worst abuse of the C preprocessor (IOCCC winner, 1986), The Three Kingdoms Enters Into Partnership with NFTb, Docker, its not rocket scienceUnderstanding Container and Docker CLIPart I, http://127.0.0.1:8000/info?limit=10&score=100. (2) Uncomment # openapi_prefix="/prod" in app/main.py. Pair programming and code reviews are considered alternatives, but is this really true? We're importing the connect_to_db and close_db_connection functions from our db/tasks.py file, though we haven't defined those yet. After all settings are done, choose Create database. Each one returns an async function that's responsible for creating our database connection and shutting it down. connecting fastapi to mysql server . We can easily fix this by implementing a simple in-memory cache for get_tenant. To finish the transition to our multitenant system, we also need to add a tenant record to our newly created tables. We're also going to create some alembic-specific files for our migrations, and a base.py file in repositories. The next step is to decide for each table whether it should be tenant specific or shared across tenants. This will take a few mins. When the environment creation process completes, open web site with eb open. How to drop a PostgreSQL database if there are active connections to it? By using this feature of SQLAlchemy we can build a context manager function that returns a database session with any tenant mapping we want: The highlighted lines show how we remap tenant to the schema passed via the tenant_schema parameter. No payment information required. Multitenancy with FastAPI, SQLAlchemy and PostgreSQL, Each tenant should get its own set of database tables, with the possibility of shared tables, Tenant handling should be done implicitly/automatically, The architecture should make it hard to accidentally access the wrong data, Support for alembic migrations across all tenants in a single transaction, Easy way to upgrade an existing code base, No support for foreign keys into shared data, You cannot use transactions across tenants, Replication setups and backups require more work, Foreign keys into shared data are possible, Transactions across tenants are supported, Removing a tenant is difficult, each table needs to be removed, No hierarchy, number of tables can grow large, Removing a tenant is difficult, all affected rows need to be removed, One large index instead of multiple smaller indices, Duplicate all tenant specific types and use, Move all tenant specific tables and types into this new schema. What we've done here is compose a number of environment variables into a single database connection string that we'll use to link our FastAPI app to our postgres db. Connect to Azure Database for PostgreSQL using psycopg2. This can be achieved by passing a schema_translate_map to the execution_options of an SQLAlchemy Connection. The only tricky part is the Alembic migrations. full-stack-fastapi-postgresql is a Python library typically used in Devops, Continuous Deployment, Docker, Swagger applications. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. However, there is an automatic interactive API doc provided by Swagger UI in FastAPI, so youare able to go to http://127.0.0.1:8000/docs to interact API as follows: When we declare other function parameters that are not part of the path parameters, they are parsed as query parameters. Now we can create the FastAPI app instance and get the data from the database. Querying the tenant from the database for each incoming request is also not super efficient. Why are you not setting the DNS string for the DB directly instead of glue them later? and associate a connection with the context. If all is well, the file will resemble the following: The first thing we'll do is define an additional function for creating our cleanings table. rev2022.11.7.43014. Create an environment and deploy application to it with eb create, like eb create region us-east-1 CHOOSE-YOUR-NAME. Open the integrated terminal in VS Code or your IDE and run the following commands to create a virtual environment: Windows Machine: $ py -3 -m venv venv. In some cases the database mapping itself is not sufficient. index: True or False. "Database is not up-to-date. Step 7: Migrations. By using a pre-made container image it's very easy to combine and use different tools. Starlette provides a Config object that allows us to specify a file - .env - to look for environment variables in. In my case I forgot to change postgres url in alembic.ini file. Now we have all the dependencies we need to write our tenant_create function: The function inserts an entry into our tenant table, creates the schema as well as all tenant specific tables. For further clarification, I've pushed my code to GitHub & it can be accessed at this repository - Self_calculation. Does a beard adversely affect playing the violin or viola? Is it possible for a gas fired boiler to consume more energy when heating intermitently versus having heating at all times? Is this meat that I was told was brisket in Barcelona the same as U.S. brisket? We can add other tasks here later, but this is all we need for now. On top of that, we need to configure our alembic environment - usually done in an alembic.ini file located in our base directory: backend. Removing a tenant is even simpler and can be done in 2 lines: Drop the schema and remove the entry from the tenant tables. A product by Sysmagine to increase the efficiency of your code review workflow. In this example, we'll use SQLite, because it uses a single file and Python has integrated support. Nonetheless, I couldn't find any guides on how to serve HTML with FastAPI. This file is responsible for creating the model for the database. connect (host = "localhost", port = "5432", dbname = "testdb", user = "postgres", password = "samplepassword") db_connection. Is this homebrew Nystul's Magic Mask spell balanced? 'postgresql://db_username:[email protected]_server:db_server_port/database_name?sslmode=prefer' Create database instance. Our database and server are now connected to each other. The next step is to create the tenant specific tables each time a new tenant is added to our system. SQLAlchemy makes this very simple. import os DATABASE_URL = os.environ.get ('DATABASE_URL') Share. If you are using SQLAlchemy Enums in PostgreSQL, we have to decide where to store them. Step 8: Upgrading an existing database. If you press Enter, the program will use the default value specified in the square bracket [] and move the cursor to the new line. With that out of the way, we can start adding config data to our .env file. In this example that would be a123bc007edf. Create another file and name it schema.py . Follow us on social media to stay up to date. Price is represented by a floating point number, with 2 decimal places. to display their name in the frontend. Setting up FastAPI Start by creating a new folder to hold your project called "fastapi-react": $ mkdir fastapi-react $ cd fastapi-react We will therefore use a trick: We use tenant as schema name, but instruct SQLAlchemy to dynamically remap it to schema of the current tenant. For example, to try . Installation: pip install pipenv pipenv shell pipenv install fastapi fastapi-sqlalchemy pydantic alembic psycopg2 uvicorn python-dotenv Step 2. Async PostgreSQL with FastAPI dependency injection & SQLAlchemy. . First, head into the .gitignore file we made earlier and add the following: Then go ahead and initialize git, and make the first commit. We instead need a way to create only the shared part of our database. My profession is written "Unemployed" on my passport. As long as you have valid credentials, you can establish a connection with few lines of code. Each tenant has its own user list and we want to return different results depending on the tenant requesting /users/{user_id}. Volumes exist so that our containers can maintain state between runs. Migrating all tables and types in your database is a bit tedious and most probably not justified if you can just recreate your database. Also when you write an answer, explain what went wrong & what specific lines of code are doing. Now we can enter commands directly into the terminal to interact with our database. How do you work with other schemas then? How to deploy a FastAPI app using PostgreSQL as a database on Heroku, Going from engineer to entrepreneur takes more than just good code (Ep. (clarification of a documentary), Substituting black beans for ground beef in a meat pie. Connect and share knowledge within a single location that is structured and easy to search. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Lets assume your API function looks like the following code from the FastAPI tutorial. If you already own a custom domain lets say example.com, then you can point your domains A record with @ pointing to the VMs public IP address . Take note of that - we're going to come back and fix it later on. FastAPI works with any database and any style of library to talk to the database. Many auto-generated scripts needs some tweaking anyways, since Alembic can not yet handle all types of changes yet, like adding a value to an existing PostgreSQL enum. FastAPI has so many build-in options that make a lot of sense for building data science APIs. @D Malan I added the error message to the post. You could solved this by inserting the corresponding row directly as part of the migration script. If you missed part 1, you can find it here. Static Files in Development. { 'connections': { # Dict format for connection 'default': { 'engine': 'tortoise.backends.asyncpg', 'credentials': { 'host': 'localhost', 'port': '5432', 'user': 'tortoise', 'password': 'qwerty123', 'database': 'test', } }, # Using a DB_URL string 'default': 'postgres://postgres:qwerty123@localhost:5432/events' }, 'apps': { 'models': { 'models': ['__main__'], # If no default_connection specified, defaults to 'default' . Click the Create Database button, then pick a creation method and engine type. The two main functions - upgrade and downgrade - will be used to create and drop database tables, execute SQL commands, and each time we migrate. Based on all the code examples and long explanations, it may look difficult at first glance, but you probably need to change less than 100 lines to make it work. We decided against this solution because having a tenant with the schema tenant in our development databases could hide potential bugs where our app fails to properly remap the schema name. FastAPI doesnt require a relational database, but users are allowed to use any relational database, like PostgreSQL, MySQL, SQLite, Oracle, Microsoft SQL Server etc. Why don't math grad schools in the U.S. use entrance exams? How to Connect to PostgreSQL Using psql Installing PostgreSQL creates a default database and user account, both called 'postgres.' To log into the 'postgres' user account type the following command in the terminal: sudo -i -u postgres This example shows the command in a Debian-based distribution, Ubuntu. The task is therefore left to my motivated readers :-). (1) Replace the values in template.yml specified as {replace}. How can we achieve this? If you are using Postgres Addon on Heroku, probably your solution is simple. React is an open-source, component-based JavaScript UI library that's used for building frontend applications. How can I start PostgreSQL server on Mac OS X? Was Gandalf on Middle-earth in the Second Age? Is opposition to COVID-19 vaccines correlated with other political beliefs? Connecting FastAPI to PostgreSQL We can now use the connection string we've created to connect to our database using FastAPI's startup event. Since you only have to do this once, porting your API endpoints is ridiculously easy. All code up to this point can be found here: Hooking FastAPI Endpoints up to a Postgres Database, backend/app/db/__init__.py backend/app/db/tasks.py, # these can be configured in config as well, INFO: Connected to database postgresql://postgres:********@db:5432/postgres, backend/app/db/migrations backend/app/db/repositories, backend/app/db/migrations/script.py.mako backend/app/db/migrations/env.py, backend/app/db/repositories/__init__.py backend/app/db/repositories/base.py. We then create some constants that we'll use accross our app, cast them to the appropriate data types, and give defaults where we might want them. This doesnt guarantee that we didnt mess up the data during an upgrade but it at least ensures that the table definitions, types, are the same. Async SQL (Relational) Databases. What we actually want to do is apply this change to every tenant in our database. We'll also create a tasks file in the core directory, to wrap the startup and shutdown events for our app. Now create a migration to move them all to their new schemas: The chances are high that you dont have any shared tables yet. The same concept should also be compatible with other databases supporting schemas, but I didnt verify this. If you need to request a new certificate every time a customer starts a trial, you introduce some delays. You should see the same FastAPI website that you created and tested locally. 504), Mobile app infrastructure being decommissioned, Creating a copy of a database in PostgreSQL, Copying PostgreSQL database to another server, Save PL/pgSQL output from PostgreSQL to a CSV file, How to import CSV file data into a PostgreSQL table. This project is very much inspired by the tutorial of the databases framework itself that you can find at 'databases . Anyone who's set up postgres on their machine knows that it can be a pain in the ass at times. A planet you can take off from, but never land back. A common pattern is to use an "ORM": an "object-relational mapping" library. When starting your backend for the first time, you need to initialize the database by creating all necessary tables, types and so on. You may also be amazed how easy AWS makes it to deploy and manage web applications. Installation: pip install pipenv. For the rest of the tutorial we will use two schemas, shared for all the shared data and tenant_[NAME] for a tenant with the name [NAME]. If you are using MySQL, you are out of luck though. How do I connect my PostgreSQL database to FastAPI? Spring Data Rest - PATCH Postgres jsonb field; Convert JSON records in PostgreSQL into a Table; Postgresql order by and limit; multi-column index for string match + string similarity with pg_trgm? The idea is that get_db automatically uses the correct schema remapping based on the tenant making the request. The advantage of a multitenancy system, in contrast to a system like GitHub, is that mistakes often have fewer consequences. Here is the full code we use to initialize the database, including a check whether it already exists: After initializing our database, it is time to create our first tenant. The goal of this post will be to implement a data persistence layer. legal basis for "discretionary spending" vs. "mandatory spending" in the USA. Will Nondetection prevent an Alarm spell from triggering? To prevent this, we drop in a check to verify that all migrations were applied: That is all we need to do to add a new tenant. How can I drop all the tables in a PostgreSQL database? A pre-requirement for Alembic to work is that it initializes its own data when creating the database. Implementing multitenancy support is difficult: How do you separate the data? If you are using Postgres Addon on Heroku, probably your solution is simple. from logging.config import fileConfigfrom sqlalchemy import engine_from_configfrom sqlalchemy import poolfrom alembic import context# this is the Alembic Config object, which provides# access to the values within the .ini file in use.config = context.config# Interpret the config file for Python logging.# This line sets up loggers basically.fileConfig(config.config_file_name)# add your model's . That is easy to achieve, you can directly depend on get_tenant as well. Create a file and name it models.py. How to do an update + join in PostgreSQL? The major differences between SQLModel's create_engine and SQLAlchemy's version is that the SQLModel version adds type annotations (for editor support) and enables the SQLAlchemy "2.0" style of engines and connections.Also, we passed in echo=True so we can see the generated SQL queries in the terminal. Summary. This variable contains the escaped schema name that can be used in queries like op.execute(f"DROP TYPE {schema_quoted}.myenum"). This was implemented in HTTP/1.1 to support name based virtual hosting, i.e. "replace" or "append". You also need a DNS record for that subdomain pointing to the IP of your server. FastAPI is very fast due to its out-of-the-box support of the async feature of Python 3.6+. Not the answer you're looking for? Connect to PostgreSQL. Last time we left off, we setup our postgresql database and configured our migration running with alembic and sqlalchemy. Making statements based on opinion; back them up with references or personal experience. Connect and share knowledge within a single location that is structured and easy to search. All we have to do, is to extract the host from the request object, lookup the corresponding tenant schema from the database and call with_db with the correct schema: Before you get too excited though, the shown solution has one drawback. This will open a browser window using the domain name created for your application. How to exit from PostgreSQL command line utility: psql. By default, based on the project name. cursor # db cursor # 2. Once we have DATABASE_URL url built, create instance of database by adding the following line to main.py The best thing you can do is to read the official documentation at fastapi.tiangolo.com, it is amazing and explains all the basics in a very detailed way. Step 1. Though there are advantages to creating multiple migration files, we're going to start with one large migration file and modify it incrementally as we build our application. Follow. The app allows users to post requests to have their residence cleaned, and other users can select a cleaning project for a given hourly rate. The idea of multitenancy is to give each customer (tenant) the illusion of their own separate workspace, while using the same backend and resources. In the next post, we'll flesh out our router with the appropriate endpoints, and test our endpoints using Pytest and Docker. A somewhat simple solution we came up with was to create a function decorator that calls a function for every tenant in our database. Why does sending via a UdpClient cause subsequent receiving to fail? Can you check the logs for more detailed error message? If you have used PostgreSQL in the past and opened your database in pgAdmin, you have most likely come across the Schemas list. I personally avoid using this approach though, because it is easy to forget that you have altered the search path and suddenly work with the wrong data. Sci-Fi Book With Cover Of A Person Driving A Ship Saying "Look Ma, No Hands!". Finally, we need to remember the host name under which the tenant is reachable. To access PostgreSQL settings, hover your mouse over the Configuration (gear) icon, then click Data Sources, and then click the PostgreSQL data source. There are several ways to achieve this, all with their own pros and cons. How to link a folder with an existing Heroku app. In main.py, import the router: from routers import users. In this article we will learn how to use Python to perform the following tasks: Create Azure Database for PostgreSQL using azure python sdk. It gets complicated if you actually want to share some data across tenants, you allocate resources for tenants even if they dont use your app and managing hundreds of VMs or containers is not trivial. Welcome to Part 2 of Up and Running with FastAPI. serving multiple websites using the same IP and port. For this we created the script alembic/tenant.py: We can now import for_each_tenant_schema from a migration script and put all tenant specific upgrades into a function using this decorator. Learn in which situations either approach performs well and how a combination can lead to the best results.