Fix 500: use 'or' fallback for env vars, guard eligible-patient query against Neo4j not ready

backend/graphrag.py

@@ -44,10 +44,10 @@ def _get_graph():
     global _graph
     if _graph is None:
         _graph = Neo4jGraph(
-            url=os.getenv("NEO4J_URI", "bolt://127.0.0.1:7687"),
-            username=os.getenv("NEO4J_USERNAME", "neo4j"),
-            password=os.getenv("NEO4J_PASSWORD", "clinicalmatch2024"),
-            database=os.getenv("NEO4J_DATABASE", "neo4j"),
+            url=os.getenv("NEO4J_URI") or "bolt://127.0.0.1:7687",
+            username=os.getenv("NEO4J_USERNAME") or "neo4j",
+            password=os.getenv("NEO4J_PASSWORD") or "clinicalmatch2024",
+            database=os.getenv("NEO4J_DATABASE") or "neo4j",
         )
     return _graph
 

backend/neo4j_setup.py

@@ -47,10 +47,10 @@ class Neo4jConnection:
 
 
 neo4j_conn = Neo4jConnection(
-    uri=os.getenv("NEO4J_URI", "bolt://127.0.0.1:7687"),
-    user=os.getenv("NEO4J_USERNAME", "neo4j"),
-    password=os.getenv("NEO4J_PASSWORD", "clinicalmatch2024"),
-    database=os.getenv("NEO4J_DATABASE", "neo4j"),
+    uri=os.getenv("NEO4J_URI") or "bolt://127.0.0.1:7687",
+    user=os.getenv("NEO4J_USERNAME") or "neo4j",
+    password=os.getenv("NEO4J_PASSWORD") or "clinicalmatch2024",
+    database=os.getenv("NEO4J_DATABASE") or "neo4j",
 )
 
 

backend/trial_enrichment.py

@@ -172,15 +172,18 @@ def get_eligible_patient_counts(nct_ids: list[str]) -> dict[str, int]:
     """Batch version — returns {nct_id: count} for a list of trials."""
     if not nct_ids:
         return {}
-    rows = neo4j_conn.run_query(
-        """
-        MATCH (p:Patient)-[:ELIGIBLE_FOR]->(t:Trial)
-        WHERE t.id IN $ids
-        RETURN t.id AS nct_id, count(p) AS n
-        """,
-        {"ids": nct_ids},
-    )
-    return {row["nct_id"]: row["n"] for row in rows}
+    try:
+        rows = neo4j_conn.run_query(
+            """
+            MATCH (p:Patient)-[:ELIGIBLE_FOR]->(t:Trial)
+            WHERE t.id IN $ids
+            RETURN t.id AS nct_id, count(p) AS n
+            """,
+            {"ids": nct_ids},
+        )
+        return {row["nct_id"]: row["n"] for row in rows}
+    except Exception:
+        return {}
 
 
 def get_similar_trials(nct_id: str, limit: int = 5) -> list[dict]: