Create main.py

main.py

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+"""FastAPI Backend for OpenNL2SQL - Simplified for HuggingFace Spaces
+Author: Amal SP
+Created: December 2025
+"""
+
+from fastapi import FastAPI, HTTPException
+from fastapi.middleware.cors import CORSMiddleware
+from pydantic import BaseModel
+from typing import Optional, List, Dict, Any
+import os
+import logging
+
+# Configure logging
+logging.basicConfig(
+    level=logging.INFO,
+    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
+)
+logger = logging.getLogger(__name__)
+
+# Initialize FastAPI app
+app = FastAPI(
+    title="OpenNL2SQL API",
+    description="AI-powered Natural Language to SQL Analytics System",
+    version="1.0.0"
+)
+
+# CORS configuration
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# Request/Response Models
+class QueryRequest(BaseModel):
+    question: str
+    session_id: Optional[str] = None
+
+class QueryResponse(BaseModel):
+    success: bool
+    sql: Optional[str] = None
+    results: Optional[List[Dict[str, Any]]] = None
+    sql_explanation: Optional[str] = None
+    results_explanation: Optional[str] = None
+    error: Optional[str] = None
+    session_id: str
+
+@app.get("/")
+async def root():
+    """Health check endpoint"""
+    return {
+        "status": "healthy",
+        "service": "OpenNL2SQL API",
+        "version": "1.0.0",
+        "message": "FastAPI backend is running on Hugging Face Spaces!"
+    }
+
+@app.get("/health")
+async def health_check():
+    """Detailed health check"""
+    return {
+        "status": "healthy",
+        "groq_api_configured": bool(os.getenv("GROQ_API_KEY")),
+        "service": "OpenNL2SQL API"
+    }
+
+@app.post("/query", response_model=QueryResponse)
+async def process_query(request: QueryRequest):
+    """Process natural language query"""
+    # For now, return a placeholder response
+    # This will be integrated with GROQ API and full backend logic
+    session_id = request.session_id or "demo-session"
+    
+    return QueryResponse(
+        success=True,
+        sql="SELECT * FROM demo_table LIMIT 10;",
+        results=[{"status": "Backend is running! Full implementation coming soon."}],
+        sql_explanation="This is a demo response. Full NL2SQL functionality will be integrated.",
+        results_explanation="The backend is successfully deployed on Hugging Face Spaces.",
+        session_id=session_id
+    )
+
+if __name__ == "__main__":
+    import uvicorn
+    uvicorn.run(app, host="0.0.0.0", port=7860)