Update src/database_center.py

src/database_center.py

@@ -12,7 +12,7 @@ import os
 # db=firestore.client()   
 
 #db_transaction=db.collection('test_transactions')
-cred_json=os.getenv['Firebase_Credential']
+cred_json=os.getenv('Firebase_Credential')
 if not firebase_admin._apps:
     cred = credentials.Certificate(json.loads(cred_json))
     firebase_admin.initialize_app(cred)