WIP: initial fastapi endpoint implementation

Client endpoint - GET & POST implemented

backend/app/api/deps.py

@@ -0,0 +1,30 @@
+"""
+"""
+from fastapi import Depends
+from sqlmodel import Session, SQLModel, select
+from app.core.db import get_session
+from app.schemas.models import Client
+from typing import Type, Optional, Annotated
+
+
+SessionDep = Annotated[Session, Depends(get_session)]
+
+
+def exists(session: Session, model: Type[SQLModel], **filters) -> Optional[bool]:
+    """
+    Checks if a request exists in the given model using any filters.
+
+    Example:
+        exists(session, Client, phone="0781232465", tax_number="TIN123")
+    """
+    if not filters:
+        raise ValueError("At least one filter must be provided")
+
+    stmt = select(model)
+    for field, value in filters.items():
+        if not hasattr(model, field):
+            raise ValueError(f"Invalid filter field: {field}")
+        stmt = stmt.where(getattr(model, field) == value)
+
+    result = session.exec(stmt).first()
+    return result is not None