fix(hooks): reset Tx to pooled connection for post-commit hook calls

BeforeScan (restheadspec handleUpdate) and BeforeResponse (funcspec
list/single query handlers) fire after RunInTransaction commits, but
hookCtx.Tx still pointed at the now-dead transaction. Any hook that
executed a query against Tx (e.g. setUserViaContext) failed with
"sql: transaction has already been committed or rolled back".

pkg/funcspec/function_api.go

@@ -331,7 +331,10 @@ func (h *Handler) SqlQueryList(sqlquery string, options SqlQueryOptions) HTTPFun
 		w.Header().Set("Content-Range", fmt.Sprintf("items %d-%d/%d", respOffset, respOffset+len(dbobjlist), total))
 		logger.Info("Serving: Records %d of %d", len(dbobjlist), total)
 
-		// Execute BeforeResponse hook
+		// Execute BeforeResponse hook. The transaction has already committed by
+		// this point, so hooks must use the pooled connection rather than the
+		// now-dead tx.
+		hookCtx.Tx = h.db
 		hookCtx.Result = dbobjlist
 		hookCtx.Total = total
 		if err := h.hooks.Execute(BeforeResponse, hookCtx); err != nil {
@@ -631,7 +634,10 @@ func (h *Handler) SqlQuery(sqlquery string, options SqlQueryOptions) HTTPFuncTyp
 			return
 		}
 
-		// Execute BeforeResponse hook
+		// Execute BeforeResponse hook. The transaction has already committed by
+		// this point, so hooks must use the pooled connection rather than the
+		// now-dead tx.
+		hookCtx.Tx = h.db
 		hookCtx.Result = dbobj
 		if err := h.hooks.Execute(BeforeResponse, hookCtx); err != nil {
 			logger.Error("BeforeResponse hook failed: %v", err)

pkg/restheadspec/handler.go

@@ -1498,6 +1498,9 @@ func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, id
 	// Execute BeforeScan hooks so row security is re-applied to the post-update
 	// re-fetch, same as it is for the initial read and the update query itself.
 	// Without this, the re-fetch can return a row the caller isn't authorized to see.
+	// The transaction has already committed by this point, so hooks must use the
+	// pooled connection rather than the now-dead tx.
+	hookCtx.Tx = h.db
 	hookCtx.Query = selectQuery
 	if err := h.hooks.Execute(BeforeScan, hookCtx); err != nil {
 		logger.Error("BeforeScan hook failed: %v", err)