How do you pass back a custom error message from google apps scripts?

Question

When running a google apps script from a google spreadsheet, if one of the google apis is used incorrectly a red \"butterbar\" error is shown at the top of the spreadsheet.

Answer 1

Here is the best way to pass data from your script into your error message. First setup a global variable object to store your data that you need for the error handling. Then store data to this object in each function's try{} section. Finally in catch(e) call an errHandler function that will pass the error data object. See the following code: code.gs.

var onErrObj = {}
function myFunction(){

 try{
  // function code goes here;
  // add more elements to onErrObj as desired;
 }catch(e){
      onErrObj['data1'] = 'someData';
      onErrObj['data'] = 'some Other Data';
      errHandler(e,'myFunction');
 }

 function errHandler(e,strFunc){
      var message = e.message+'\n in file: '+e.fileName+' on line: '+e.lineNumber;
      var sendto = 'yourname@youremail.com';
      var subject = 'My App encountered an error occured in '+strFunc;
      var errProps = JSON.stringify(this.onError);
      message = subject+'\n'+message+'\n onError: '+errProps;
      GmailApp.sendEmail(sendto, subject, message); 
}