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"""
Database connection and models for sentiment API
Uses SQLAlchemy ORM for clean database interactions
PostgreSQL for persistent storage (runs in Docker container - FREE!)
"""
from sqlalchemy import create_engine, Column, Integer, String, Float, DateTime
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from datetime import datetime
import os
# Get database URL from environment variable
# Set by docker-compose.yml
DATABASE_URL = os.getenv(
"DATABASE_URL",
"postgresql://user:pass@localhost:5432/sentiment" # Fallback for local dev
)
# Create database engine
# This connects to PostgreSQL container
engine = create_engine(DATABASE_URL)
# Create session factory
# Sessions are like "conversations" with the database
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
# Base class for database models
Base = declarative_base()
# Database Model (Table Definition)
class SentimentAnalysis(Base):
"""
Stores sentiment analysis results
Table: sentiment_analyses
"""
__tablename__ = "sentiment_analyses"
# Primary key (auto-incrementing ID)
id = Column(Integer, primary_key=True, index=True)
# The text that was analyzed
text = Column(String(512), nullable=False)
# Sentiment result (POSITIVE or NEGATIVE)
sentiment = Column(String(50), nullable=False)
# Confidence score (0.0 to 1.0)
confidence = Column(Float, nullable=False)
# Processing time in milliseconds
processing_time_ms = Column(Integer, nullable=False)
# When this analysis was created
created_at = Column(DateTime, default=datetime.utcnow, nullable=False)
# Create all tables in the database
# This runs when the app starts
def init_db():
"""
Initialize database tables
Creates sentiment_analyses table if it doesn't exist
Safe to call multiple times (won't recreate existing tables)
"""
Base.metadata.create_all(bind=engine)
# Dependency for FastAPI routes
# Provides a database session to each request
def get_db():
"""
FastAPI dependency that provides a database session
Usage in routes:
@app.post("/analyze")
def analyze(db: Session = Depends(get_db)):
# Use db here
pass
Automatically closes session after request
"""
db = SessionLocal()
try:
yield db
finally:
db.close() |