SelectionDeleting even

when i used SelectionDeleting even delete data from mysql i need key ,
how can i do it , i don’t get node key ,Bf {aa: D, Sb: “SelectionDeleting”, Ow: I, xw: null, Xq: false}
当我使用SelectionDeleting事件从我的数据库删除事件时我需要一个节点的key,但是我取不到,我该如何从Bf中取出key?

i know e.subject.each(function(n){console.log(n.data.key)});