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database.py — SQLAlchemy ORM models and session management.
Tables:
contracts — one row per ingested contract
clauses — one row per extracted clause (FK → contracts)
analysis_results — one row per analysis run linking all scores
All timestamps are stored as ISO-8601 UTC strings for SQLite compatibility.
"""
import sys
from contextlib import contextmanager
from datetime import datetime, timezone
from pathlib import Path
from typing import Generator, Optional
from sqlalchemy import (
Boolean,
Column,
DateTime,
Float,
ForeignKey,
Integer,
String,
Text,
create_engine,
event,
)
from sqlalchemy.orm import DeclarativeBase, Session, relationship, sessionmaker
sys.path.insert(0, str(Path(__file__).parent.parent))
import config
# Engine & Session
engine = create_engine(
config.DB_URL,
connect_args={"check_same_thread": False}, # SQLite requires this for FastAPI
echo=False,
)
# Enable WAL mode for better concurrent read performance with SQLite
@event.listens_for(engine, "connect")
def set_sqlite_pragma(dbapi_connection, connection_record):
"""Enable WAL mode and foreign key enforcement on every new SQLite connection."""
cursor = dbapi_connection.cursor()
cursor.execute("PRAGMA journal_mode=WAL")
cursor.execute("PRAGMA foreign_keys=ON")
cursor.close()
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
# ORM Base
class Base(DeclarativeBase):
"""Declarative base for all ORM models."""
pass
# ORM Models
class Contract(Base):
"""Represents a single ingested contract document.
Attributes:
contract_id: MD5-based unique identifier derived from filename.
filename: Original filename or identifier string.
source: Origin of contract ('CUAD', 'upload', 'text_input').
page_count: Number of pages (for PDFs).
created_at: UTC timestamp of ingestion.
clauses: Relationship to associated Clause rows.
"""
__tablename__ = "contracts"
contract_id = Column(String(64), primary_key=True, index=True)
filename = Column(String(512), nullable=False)
source = Column(String(64), nullable=False, default="upload")
page_count = Column(Integer, nullable=True)
created_at = Column(
DateTime,
default=lambda: datetime.now(timezone.utc),
nullable=False,
)
clauses = relationship("Clause", back_populates="contract", cascade="all, delete-orphan")
results = relationship("AnalysisResult", back_populates="contract", cascade="all, delete-orphan")
def __repr__(self) -> str:
return f"<Contract id={self.contract_id} file={self.filename}>"
class Clause(Base):
"""Represents a single clause extracted from a contract.
Attributes:
clause_id: MD5-based unique identifier.
contract_id: FK to contracts table.
clause_text: Raw text of the clause.
clause_type: Pipe-separated list of CUAD clause type labels.
party_a: Name of Party A as detected in clause.
party_b: Name of Party B as detected in clause.
source: Origin ('CUAD', 'upload', 'text_input').
anomaly_score: Combined anomaly risk score (0–100).
is_anomalous: True if anomaly_score > ANOMALY_FLAG_THRESHOLD.
power_imbalance_score: Bilateral imbalance score (-100 to +100).
party_a_leverage: Party A leverage score (0–100).
party_b_leverage: Party B leverage score (0–100).
sentiment_score: Sentiment feature value.
modal_score: Modal verb feature value.
obligation_score: Obligation assignment feature value.
assertiveness_score: Assertiveness feature value.
shap_plot_path: Filesystem path to the SHAP PNG for this clause.
created_at: UTC timestamp of processing.
"""
__tablename__ = "clauses"
clause_id = Column(String(64), primary_key=True, index=True)
contract_id = Column(String(64), ForeignKey("contracts.contract_id"), nullable=False, index=True)
clause_text = Column(Text, nullable=False)
clause_type = Column(String(512), nullable=False, default="")
party_a = Column(String(256), nullable=True, default="")
party_b = Column(String(256), nullable=True, default="")
source = Column(String(64), nullable=True, default="")
# Anomaly detection fields
anomaly_score = Column(Float, nullable=True)
is_anomalous = Column(Boolean, nullable=True, default=False)
# Power imbalance fields
power_imbalance_score = Column(Float, nullable=True)
party_a_leverage = Column(Float, nullable=True)
party_b_leverage = Column(Float, nullable=True)
# Feature-level scores
sentiment_score = Column(Float, nullable=True)
modal_score = Column(Float, nullable=True)
obligation_score = Column(Float, nullable=True)
assertiveness_score = Column(Float, nullable=True)
# Explainability
shap_plot_path = Column(String(512), nullable=True)
created_at = Column(
DateTime,
default=lambda: datetime.now(timezone.utc),
nullable=False,
)
contract = relationship("Contract", back_populates="clauses")
def __repr__(self) -> str:
return f"<Clause id={self.clause_id} type={self.clause_type[:30]}>"
class AnalysisResult(Base):
"""Stores aggregate analysis results at the contract level.
Attributes:
result_id: Auto-incremented primary key.
contract_id: FK to contracts table.
overall_imbalance_index: Contract-level power imbalance (-100 to +100).
total_clauses: Total clause count.
anomalous_clauses: Count of flagged anomalous clauses.
dominant_clause_type: Most frequent clause type in the contract.
analysis_metadata: JSON string with additional metadata.
created_at: UTC timestamp.
"""
__tablename__ = "analysis_results"
result_id = Column(Integer, primary_key=True, autoincrement=True)
contract_id = Column(String(64), ForeignKey("contracts.contract_id"), nullable=False, index=True)
overall_imbalance_index = Column(Float, nullable=True)
total_clauses = Column(Integer, nullable=True)
anomalous_clauses = Column(Integer, nullable=True)
dominant_clause_type = Column(String(256), nullable=True)
analysis_metadata = Column(Text, nullable=True) # JSON string
created_at = Column(
DateTime,
default=lambda: datetime.now(timezone.utc),
nullable=False,
)
contract = relationship("Contract", back_populates="results")
def __repr__(self) -> str:
return f"<AnalysisResult contract={self.contract_id} imbalance={self.overall_imbalance_index}>"
# Utility functions
def create_tables() -> None:
"""Create all database tables if they do not already exist.
Safe to call multiple times — uses CREATE TABLE IF NOT EXISTS semantics.
"""
Base.metadata.create_all(bind=engine)
def get_db() -> Generator[Session, None, None]:
"""FastAPI dependency that provides a database session per request.
Yields:
SQLAlchemy Session instance. Automatically closed after use.
"""
db = SessionLocal()
try:
yield db
finally:
db.close()
@contextmanager
def managed_session() -> Generator[Session, None, None]:
"""Context manager for database sessions outside of FastAPI request scope.
Usage:
with managed_session() as session:
session.add(some_object)
session.commit()
"""
session = SessionLocal()
try:
yield session
session.commit()
except Exception:
session.rollback()
raise
finally:
session.close()
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