feat: Refactor Fund schema to use many-to-many relationships for investment stages and sectors

- Updated FundTable to replace JSON fields for investment stages and sectors with relationships.
- Introduced InvestmentStageTable and fund_investment_stages association table.
- Created fund_sectors association table for many-to-many relationship with sectors.
- Changed geographic_focus from JSON array to a simple string.
- Migrated existing data to new schema, ensuring data integrity and normalization.
- Updated related schemas, routers, and services to reflect new structure.
- Added migration script to handle data transformation and schema updates.
- Implemented tests to verify new relationships and data integrity.

app/db/models.py

@@ -70,6 +70,22 @@ project_company_association = Table(
     Column("company_id", Integer, ForeignKey("companies.id")),
 )
 
+# Association table for fund-stage many-to-many
+fund_investment_stages_association = Table(
+    "fund_investment_stages",
+    Base.metadata,
+    Column("fund_id", Integer, ForeignKey("funds.id")),
+    Column("stage_id", Integer, ForeignKey("investment_stages.id")),
+)
+
+# Association table for fund-sector many-to-many
+fund_sectors_association = Table(
+    "fund_sectors",
+    Base.metadata,
+    Column("fund_id", Integer, ForeignKey("funds.id")),
+    Column("sector_id", Integer, ForeignKey("sectors.id")),
+)
+
 
 class InvestorTable(Base, TimestampMixin):
     __tablename__ = "investors"
@@ -172,13 +188,21 @@ class FundTable(Base, TimestampMixin):
     source_url = Column(String, nullable=True)
     source_provider = Column(String, nullable=True)  # e.g., "Perplexity"
 
-    # JSON array fields
-    geographic_focus = Column(JSON, nullable=True)  # Array of regions/countries
-    investment_stage_focus = Column(JSON, nullable=True)  # Array of stages
-    sector_focus = Column(JSON, nullable=True)  # Array of sectors
+    # Geographic focus as simple string
+    geographic_focus = Column(String, nullable=True)
 
     # Relationships
     investor = relationship("InvestorTable", back_populates="funds")
+    investment_stages = relationship(
+        "InvestmentStageTable",
+        secondary=fund_investment_stages_association,
+        back_populates="funds",
+    )
+    sectors = relationship(
+        "SectorTable",
+        secondary=fund_sectors_association,
+        back_populates="funds",
+    )
 
 
 class CompanyTable(Base, TimestampMixin):
@@ -224,26 +248,43 @@ class CompanyMember(Base, TimestampMixin):
     company = relationship("CompanyTable", back_populates="members")
 
 
+class InvestmentStageTable(Base, TimestampMixin):
+    __tablename__ = "investment_stages"
+
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String, nullable=False, unique=True)
+
+    # Relationships
+    funds = relationship(
+        "FundTable",
+        secondary=fund_investment_stages_association,
+        back_populates="investment_stages",
+    )
+
+
 class SectorTable(Base, TimestampMixin):
     __tablename__ = "sectors"
 
     id = Column(Integer, primary_key=True, index=True)
     name = Column(String, nullable=False)
 
-    # Add relationship back to investors
+    # Relationships
     investors = relationship(
         "InvestorTable",
         secondary=investor_sector_association,
         back_populates="sectors",
     )
-
     companies = relationship(
         "CompanyTable", secondary=company_sector_association, back_populates="sectors"
     )
-
     projects = relationship(
         "ProjectTable", secondary=project_sector_association, back_populates="sector"
     )
+    funds = relationship(
+        "FundTable",
+        secondary=fund_sectors_association,
+        back_populates="sectors",
+    )
 
 
 class ProjectTable(Base, TimestampMixin):