FastAPI Quick CRUD

• Introduction
  • Advantage
  • Constraint
• Getting started
  • Installation
  • Usage
• Design
  • Path Parameter
  • Query Parameter
  • Request Body
  • Upsert

Introduction

I believe that everyone who's working with FastApi and building some RESTful of CRUD services, wastes the time to writing similar code for simple CRUD every time

FastAPI Quick CRUD can generate CRUD in FastApi with SQLAlchemy schema of PostgreSQL Database.

• Get one
• Get many
• Update one
• Update many
• Patch one
• Patch many
• Create/Upsert one
• Create/Upsert many
• Delete One
• Delete Many
• Post Redirect Get

FastAPI Quick CRUDis developed based on SQLAlchemy 1.4.23 version and supports sync and async.

Advantage

• Support SQLAlchemy 1.4 - Allow you build a fully asynchronous python service, also supports synchronization.

• Support Pagination - Get many API support order by offset limit field in API

• Rich FastAPI CRUD router generation - Many operations of CRUD are implemented to complete the development and coverage of all aspects of basic CRUD.

• CRUD route automatically generated - Support Declarative class definitions and Imperative table

• Flexible API request - UPDATE ONE/MANY FIND ONE/MANY PATCH ONE/MANY DELETE ONE/MANY supports Path Parameters (primary key) and Query Parameters as a command to the resource to filter and limit the scope of the scope of data in request.

Constraint

• ❌ Only Support PostgreSQL yet (support MongoDB,MSSQL in schedule)
• ❌ If there are multiple unique constraints, please use composite unique constraints instead
• ❌ Composite primary key is not support
• ❌ Not Support API requests with specific resource xxx/{primary key} when table have not primary key;
  • UPDATE ONE
  • FIND ONE
  • PATCH ONE
  • DELETE ONE
• ❌ Alias is not support for imperative table yet
• ❌ Some types of columns are not supported as query parameter
  • INTERVAL
  • JSON
  • JSONB
  • H-STORE
  • ARRAY
  • BYTE
  • Geography
  • box
  • line
  • point
  • lseg
  • polygon
  • inet
  • macaddr

Getting started

Installation

pip install fastapi-quickcrud

Usage

Start PostgreSQL using:

docker run -d -p 5432:5432 --name mypostgres --restart always -v postgresql-data:/var/lib/postgresql/data -e POSTGRES_PASSWORD=1234 postgres

Simple Code (get more example from ./example)

from datetime import datetime, timezone

import uvicorn
from fastapi import FastAPI
from sqlalchemy import Column, Integer, \
    String, Table, ForeignKey
from sqlalchemy.orm import declarative_base, sessionmaker

from fastapi_quickcrud import CrudMethods
from fastapi_quickcrud import crud_router_builder
from fastapi_quickcrud import sqlalchemy_table_to_pydantic
from fastapi_quickcrud import sqlalchemy_to_pydantic

app = FastAPI()

Base = declarative_base()
metadata = Base.metadata

from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession

engine = create_async_engine('postgresql+asyncpg://postgres:[email protected]:5432/postgres', future=True, echo=True,
                             pool_use_lifo=True, pool_pre_ping=True, pool_recycle=7200)
async_session = sessionmaker(bind=engine, class_=AsyncSession)


async def get_transaction_session() -> AsyncSession:
    async with async_session() as session:
        async with session.begin():
            yield session


class User(Base):
    __tablename__ = 'users'

    id = Column(Integer, primary_key=True, autoincrement=True, unique=True)
    name = Column(String, nullable=False)
    email = Column(String, nullable=False, default=datetime.now(timezone.utc).strftime('%H:%M:%S%z'))


friend = Table(
    'friend', metadata,
    Column('id', ForeignKey('users.id', ondelete='CASCADE', onupdate='CASCADE'), nullable=False),
    Column('friend_name', String, nullable=False)
)

user_model_set = sqlalchemy_to_pydantic(db_model=User,
                                        crud_methods=[
                                            CrudMethods.FIND_MANY,
                                            CrudMethods.FIND_ONE,
                                            CrudMethods.UPSERT_ONE,
                                            CrudMethods.UPDATE_MANY,
                                            CrudMethods.UPDATE_ONE,
                                            CrudMethods.DELETE_ONE,
                                            CrudMethods.DELETE_MANY,
                                            CrudMethods.PATCH_MANY,

                                        ],
                                        exclude_columns=[])

friend_model_set = sqlalchemy_table_to_pydantic(db_model=friend,
                                                crud_methods=[
                                                    CrudMethods.FIND_MANY,
                                                    CrudMethods.UPSERT_MANY,
                                                    CrudMethods.UPDATE_MANY,
                                                    CrudMethods.DELETE_MANY,
                                                    CrudMethods.PATCH_MANY,

                                                ],
                                                exclude_columns=[])


crud_route_1 = crud_router_builder(db_session=get_transaction_session,
                                   crud_models=user_model_set,
                                   db_model=User,
                                   prefix="/user",
                                   dependencies=[],
                                   async_mode=True,
                                   tags=["User"]
                                   )
crud_route_2 = crud_router_builder(db_session=get_transaction_session,
                                   crud_models=friend_model_set,
                                   db_model=friend,
                                   async_mode=True,
                                   prefix="/friend",
                                   dependencies=[],
                                   tags=["Friend"]
                                   )


app.include_router(crud_route_1)
app.include_router(crud_route_2)
uvicorn.run(app, host="0.0.0.0", port=8000, debug=False)

Main module

covert SQLAlchemy to model set

use sqlalchemy_to_pydantic if SQLAlchemy model is Declarative Base Class

use sqlalchemy_table_to_pydantic if SQLAlchemy model is Table

• argument:

  • db_model: SQLALchemy Declarative Base Class

  • crud_methods: CrudMethods

    • CrudMethods.FIND_ONE
    • CrudMethods.FIND_MANY
    • CrudMethods.UPDATE_ONE
    • CrudMethods.UPDATE_MANY
    • CrudMethods.PATCH_ONE
    • CrudMethods.PATCH_MANY
    • CrudMethods.UPSERT_ONE
    • CrudMethods.UPSERT_MANY
    • CrudMethods.DELETE_ONE
    • CrudMethods.DELETE_MANY
    • CrudMethods.POST_REDIRECT_GET

  • exclude_columns: list

    set the columns that not to be operated but the columns should nullable or set the default value)

Generate CRUD router

crud_router_builder

• db_session: execute session generator
  • example:
    • sync SQLALchemy:

def get_transaction_session():
    try:
        db = sessionmaker(...)
        yield db
        db.commit()
    except Exception as e:
        db.rollback()
        raise e
    finally:
        db.close()

• Async SQLALchemy

async def get_transaction_session() -> AsyncSession:
    async with async_session() as session:
        async with session.begin():
            yield session

• db_model SQLALchemy Declarative Base Class

  Note: There are some constraint in the SQLALchemy Schema

• async_modebool: if your db session is async

  Note: require async session generator if True

• autocommitbool: if you don't need to commit by your self

  Note: require handle the commit in your async session generator if False

• dependencies: API dependency injection of fastapi

  Note: Get the example usage in ./example

• crud_models sqlalchemy_to_pydantic

• dynamic argument (prefix, tags): extra argument for APIRouter() of fastapi

Design

In PUT DELETE PATCH, user can use Path Parameters and Query Parameters to limit the scope of the data affected by the operation, and the Query Parameters is same with FIND API

Path Parameter

In the design of this tool, Path Parameters should be a primary key of table, that why limited primary key can only be one.

Query Parameter

• Query Operation will look like that when python type of column is

  string

  • support Approximate String Matching that require this
    • (<column_name>____str, <column_name>____str_____matching_pattern)
  • support In-place Operation, get the value of column in the list of input
    • (<column_name>____list, <column_name>____list____comparison_operator)
  • preview
  numeric or datetime

  • support Range Searching from and to
    • (<column_name>____from, <column_name>____from_____comparison_operator)
    • (<column_name>____to, <column_name>____to_____comparison_operator)
  • support In-place Operation, get the value of column in the list of input
    • (<column_name>____list, <column_name>____list____comparison_operator)
  • preview
  uuid

  uuid supports In-place Operation only

  • support In-place Operation, get the value of column in the list of input
    • (<column_name>____list, <column_name>____list____comparison_operator)

• EXTRA query parameter for GET_MANY:

  Pagination

  • limit
  • offset
  • order by
  • preview

Query to SQL statement example

• Approximate String Matching

  example

  • request url

    /test_CRUD?
    char_value____str_____matching_pattern=match_regex_with_case_sensitive&
    char_value____str_____matching_pattern=does_not_match_regex_with_case_insensitive&
    char_value____str_____matching_pattern=case_sensitive&
    char_value____str_____matching_pattern=not_case_insensitive&
    char_value____str=a&
    char_value____str=b
    

  • generated sql

      SELECT *
      FROM untitled_table_256 
      WHERE (untitled_table_256.char_value ~ 'a') OR 
      (untitled_table_256.char_value ~ 'b' OR 
      (untitled_table_256.char_value !~* 'a') OR 
      (untitled_table_256.char_value !~* 'b' OR 
      untitled_table_256.char_value LIKE 'a' OR 
      untitled_table_256.char_value LIKE 'b' OR 
      untitled_table_256.char_value NOT ILIKE 'a' 
      OR untitled_table_256.char_value NOT ILIKE 'b'

• In-place Operation

  example

  • In-place support the following operation

  • generated sql if user select Equal operation and input True and False

  • preview

  • generated sql

      select * FROM untitled_table_256 
      WHERE untitled_table_256.bool_value = true OR 
      untitled_table_256.bool_value = false

• Range Searching

  example

  • Range Searching support the following operation

    

    

  • generated sql

      select * from untitled_table_256
      WHERE untitled_table_256.date_value > %(date_value_1)s 

      select * from untitled_table_256
      WHERE untitled_table_256.date_value < %(date_value_1)s 

• Also support your custom dependency for each api(there is a example in ./example)

Request Body

In the design of this tool, the columns of the table will be used as the fields of request body.

In the basic request body in the api generated by this tool, some fields are optional if :

• it is primary key with autoincrement is True or the server_default or default is True
• it is not a primary key, but the server_default or default is True
• The field is nullable

Upsert

POST API will perform the data insertion action with using the basic Request Body, In addition, it also supports upsert(insert on conflict do)

The operation will use upsert instead if the unique column in the inserted row that is being inserted already exists in the table

The tool uses unique columns in the table as a parameter of on conflict , and you can define which column will be updated

Alias

Alias is supported already

usage:

id = Column('primary_key',Integer, primary_key=True, server_default=text("nextval('untitled_table_256_id_seq'::regclass)"))

you can use info argument to set the alias name of column, and use synonym to map the column between alias column and original column

id = Column(Integer, info={'alias_name': 'primary_key'}, primary_key=True, server_default=text("nextval('untitled_table_256_id_seq'::regclass)"))
primary_key = synonym('id')

FastAPI_quickcrud Response Status Code standard

When you ask for a specific resource, say a user or with query param, and the user doesn't exist

GET: get one : https://0.0.0.0:8080/api/:userid?xx=xx

UPDATE: update one : https://0.0.0.0:8080/api/:userid?xx=xx

PATCH: patch one : https://0.0.0.0:8080/api/:userid?xx=xx

DELETE: delete one : https://0.0.0.0:8080/api/:userid?xx=xx

then fastapi-qucikcrud should return 404. In this case, the client requested a resource that doesn't exist.

In the other case, you have an api that operate data on batch in the system using the following url:

GET: get many : https://0.0.0.0:8080/api/user?xx=xx

UPDATE: update many : https://0.0.0.0:8080/api/user?xx=xx

DELETE: delete many : https://0.0.0.0:8080/api/user?xx=xx

PATCH: patch many : https://0.0.0.0:8080/api/user?xx=xx

If there are no users in the system, then, in this case, you should return 204.

TODO

• handle relationship
• support MYSQL , MSSQL cfand Sqllite