Implementing db querying

back/db.py

@@ -0,0 +1,85 @@
+from sqlalchemy import Column, Table, Integer, MetaData, String, select, create_engine
+from sqlalchemy.sql import func
+from sqlalchemy.orm import sessionmaker
+from sqlalchemy.ext.declarative import declarative_base
+
+
+SQLALCHEMY_DATABASE_URL = "sqlite:///./sql_app.db"
+
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False}
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+
+Base = declarative_base()
+
+
+class People(Base):
+    __tablename__ = "people"
+
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String)
+    age = Column(Integer)
+    gender = Column(String)
+    country = Column(String)
+
+
+def create_people_from_list(db, people_list):
+    count = 0
+    for p in people_list:
+        db_people = People(**p.dict())
+        db.add(db_people)
+        count += 1
+
+    db.commit()
+    return count
+
+
+def get_average_age_by_country(db) -> []:
+    return db.query(People.country.label('country'), func.avg(People.age).label('average_age'))\
+             .group_by( People.country).all()
+
+
+def count_people_by_country(db) -> []:
+    return db.query(People.country.label('country'), func.count(People.id).label('people_count'))\
+             .group_by( People.country).all()
+
+
+def get_gender_repartition_by_country(db, country) -> []:
+    count_women, total = db.query(
+
+        select(func.count(People.id).label('count_women')) \
+        .where(People.gender == 'F') \
+        .where(People.country == country).subquery(),
+
+        select(func.count(People.id).label('total')) \
+        .where(People.country == country).subquery(),
+
+    ).first()
+    female_proportion = count_women / total
+    return {
+        "female_proportion": female_proportion,
+        "male_proportion": 1 - female_proportion
+    }
+
+
+meta = MetaData()
+Table(
+    'people', meta,
+    Column('id', Integer, primary_key=True),
+    Column('name', String),
+    Column('age', Integer),
+    Column('gender', String),
+    Column('country', String),
+)
+meta.create_all(engine)

main.py

@@ -1,43 +1,36 @@
-from fastapi import FastAPI
+from fastapi import FastAPI, Depends
-
 from typing import List
 
+from sqlalchemy.orm import Session
+
 from back.schemas import PeopleList, AverageAgeByCountry, CountByCountry, GenderRepartition
+from back.db import get_db, create_people_from_list, get_average_age_by_country, \
+    count_people_by_country, get_gender_repartition_by_country
+
 
 app = FastAPI()
 
 
 @app.post("/people")
-async def create_people(people_list: PeopleList) -> dict:
+async def create_people(people_list: PeopleList, db: Session = Depends(get_db)) -> dict:
+    count = create_people_from_list(db, people_list.people)
+
     return {
         "message": "People list has been succesfully imported",
-        "records_created": 10
+        "records_created": count
     }
 
 
 @app.get("/average_age", response_model=List[AverageAgeByCountry])
-async def read_average_age() -> List[AverageAgeByCountry]:
+async def read_average_age(db: Session = Depends(get_db)) -> List[AverageAgeByCountry]:
-    return [
+    return [AverageAgeByCountry(**a) for a in get_average_age_by_country(db)]
-        {'country': 'FR', 'average_age': 15.0},
-        {'country': 'BE', 'average_age': 25.0},
-        {'country': 'DE', 'average_age': 23.3},
-        {'country': 'IT', 'average_age': 45.0},
-    ]
 
 
 @app.get("/count_by_country", response_model=List[CountByCountry])
-async def read_count_by_country() -> List[CountByCountry]:
+async def read_count_by_country(db: Session = Depends(get_db)) -> List[CountByCountry]:
-    return [
+    return [CountByCountry(**a) for a in count_people_by_country(db)]
-        {'country': 'FR', 'people_count': 2},
-        {'country': 'BE', 'people_count': 4},
-        {'country': 'DE', 'people_count': 3},
-        {'country': 'IT', 'people_count': 1},
-    ]
 
 
 @app.get("/gender_repartition/{country}", response_model=GenderRepartition)
-async def read_count_by_gender(country: str) -> GenderRepartition:
+async def read_count_by_gender(country: str, db: Session = Depends(get_db)) -> GenderRepartition:
-    return {
+    return GenderRepartition(**get_gender_repartition_by_country(db, country))
-        "female_proportion": 33.3,
-        "male_proportion": 66.6
-    }