I'm getting server Exception Error in terminal - Meteor - meteor

Question

This is the error i’m getting from terminal
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' }
this is the meteor method i wrote it in the server
getCustomerNameByAppIdReactive: function(appointmentId){
let customerId = Appointments.findOne({
_id: appointmentId}).customerId;
if (customerId == “1”){
return “Walk-In Customer”;
} else {
return Customers.findOne({_id:customerId}).name;
}
},
this is reactive-method call from client
getCustomerName: (appointmentId)=>{
return ReactiveMethod.call(“getCustomerNameByAppIdReactive”,appointmentId);
},
this method working finely but getting the error in terminal as
"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) "
Anyone if you had related with this issue ??

Answer 1

use if condition to check whether there is a return value.if your return value is null or undefined you will get the exception
let customerId = Appointments.findOne({_id: appointmentId}).customerId;
if(customerId){
}
else{
}

Answer 2

Your code assumes that a record will be found, but it's better to be defensive in your coding, and assume that things can go wrong, This is your code:
getCustomerNameByAppIdReactive: function(appointmentId){
let customerId = Appointments.findOne({
_id: appointmentId}).customerId;
if (customerId == “1”){
return “Walk-In Customer”;
} else {
return Customers.findOne({_id:customerId}).name;
}
},
The call to Appointments.findOne will return a record, but it's returning null/undefined. Hence the error message:
Cannot read property \'customerId\' of undefined
If you restructure your code to be defensive, it will yield better results, eg
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;
}
},
You could write some more defensive code on the Customers.findOne call, but I'll leave that for you to do.
This code won't blow up now (unless the customer is not found)