if语句socket io mongodb nodejs

Question

如果userally或enemyally不存在，然后不发送，该如何检查该代码。我应该先做if语句，然后再在没有用户盟友，没有敌人盟友或没有两者的情况下再做两个emits吗？

AllianceMember.findOne({username: user.username}).then((userally) => {
 AllianceMember.findOne({username: enemy.username}).then((enemyally) => {
      io.emit('fight-win', {
          username: user.username,
          useralliance: userally.ally_title,
          enemyalliance: enemyally.ally_title,
          enemyname: enemy.username,
});

Answer 1

假设它们是json对象，则可以将它们的默认值设置为空对象。

AllianceMember.findOne({username: user.username}).then((userally = {}) => {
 AllianceMember.findOne({username: enemy.username}).then((enemyally = {}) => {
      io.emit('fight-win', {
          username: user.username,
          useralliance: userally.ally_title,
          enemyalliance: enemyally.ally_title,
          enemyname: enemy.username,
});