我在终端中收到服务器异常错误 - Meteor

Question

这是我从终端得到的错误

Exception while invoking method 'getCustomerNameByAppIdReactive' { stack: 'TypeError: Cannot read property \'customerId\' of undefined
  at [object Object].getCustomerNameByAppIdReactive (server/Functions/searchFunctions.js:167:20)
    at [object Object].methodMap.(anonymous function) (packages/meteorhacks_kadira/lib/hijack/wrap_session.js:164:1)
    at maybeAuditArgumentChecks (packages/ddp-server/livedata_server.js:1711:12)
    at packages/ddp-server/livedata_server.js:711:19
    at [object Object]._.extend.withValue (packages/meteor/dynamics_nodejs.js:56:1)
 at packages/ddp-server/livedata_server.js:709:40
    at [object Object]._.extend.withValue (packages/meteor/dynamics_nodejs.js:56:1)
 at packages/ddp-server/livedata_server.js:707:46
    at tryCallTwo (/home/saran/.meteor/packages/promise/.0.7.3.3xbt0b++os+web.browser+web.cordova/npm/node_modules/promise/lib/core.js:45:5)
 at doResolve (/home/saran/.meteor/packages/promise/.0.7.3.3xbt0b++os+web.browser+web.cordova/npm/node_modules/promise/lib/core.js:200:13)', I20170824-11:47:30.445(5.5)?   source: 'method' }

这是我在服务器写的meteor方法

getCustomerNameByAppIdReactive: function(appointmentId){

  let customerId = Appointments.findOne({
    _id: appointmentId}).customerId;    
  if (customerId == “1”){   
      return “Walk-In Customer”;
  } else {
    return Customers.findOne({_id:customerId}).name;
  }
},

这是来自客户端的反应式方法调用

getCustomerName: (appointmentId)=>{
return ReactiveMethod.call(“getCustomerNameByAppIdReactive”,appointmentId);
 },

此方法运行良好，但在终端中出现错误

"Exception while invoking method ‘getCustomerNameByAppIdReactive’ { stack: 'TypeError: Cannot read property ‘customerId’ of undefined\n at [object Object].getCustomerNameByAppIdReactive (server/Functions/searchFunctions.js:167:20)\n at [object Object].methodMap.(anonymous function) "

任何与此问题相关的人？？

Answer 1

您的代码假设会找到一条记录，但最好在您的编码中采取防御措施，并假设事情可能会出错，这是您的代码：

getCustomerNameByAppIdReactive: function(appointmentId){

  let customerId = Appointments.findOne({
    _id: appointmentId}).customerId;    
  if (customerId == “1”){   
      return “Walk-In Customer”;
  } else {
    return Customers.findOne({_id:customerId}).name;
  }
},

对 Appointments.findOne 的调用将 return 一条记录，但它正在 returning null/undefined。因此错误消息：

Cannot read property \'customerId\' of undefined

如果您将代码重组为防御性的，它会产生更好的结果，例如

getCustomerNameByAppIdReactive: function(appointmentId){

  let appt = Appointments.findOne({
    _id: appointmentId});
  if (!appt) {
    console.log("Can't find an appointment record for "+appointmentId)
    return "Not found"
  }
  if (appt.customerId === “1”){   
      return “Walk-In Customer”;
  } else {
    return Customers.findOne({_id:customerId}).name;
  }
},

您可以在 Customers.findOne 调用中编写一些更具防御性的代码，但我会将其留给您。

这段代码不会爆炸（除非找不到客户）

Answer 2

使用 if 条件检查是否有 return value.if 你的 return 值为 null 或 undefined 你会得到异常

let customerId = Appointments.findOne({_id: appointmentId}).customerId; 
if(customerId){

}
else{ 

}

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