spring data - how to get error messages from mongoRepository.save() -

i'm using mongorepository.save() cannot error information when duplicates prevent insertion. test i'm inserting duplicate username , mongo ignores it. when username unique inserted expected.

see below service class:

package com.onlinedateshow.service;  import org.springframework.beans.factory.annotation.autowired; import org.springframework.data.mongodb.core.mongotemplate; import org.springframework.security.crypto.bcrypt.bcryptpasswordencoder; import org.springframework.stereotype.service;  import com.mongodb.basicdbobject; import com.onlinedateshow.data.model.user; import com.onlinedateshow.data.repo.user.userrepository; import com.onlinedateshow.model.ui.registerui; import com.onlinedateshow.model.util.registermapper;  @service public class registerservice {     @autowired     private userrepository userrepo;      @autowired     mongotemplate template;      public string adduser(registerui registerdata) {          user newuser = registermapper.topersistencebean(registerdata);          try{              //does not return error, if duplicates found, silently              //ignores query             user saveduser = userrepo.save(newuser);               //below want don't know how repository             //string error = template.getdb().getlasterror().geterrormessage();             //return error;             return null;           }catch(exception e){             return e.getlocalizedmessage();         }     }   } 

and userrepository interface:

package com.onlinedateshow.data.repo.user;   import org.springframework.data.mongodb.repository.mongorepository; import org.springframework.data.repository.pagingandsortingrepository;  import com.onlinedateshow.data.model.user;  public interface userrepository extends mongorepository<user, string>, pagingandsortingrepository<user, string> {     user findbyemail(string email);      user findbyid(string id);      user findbyusername(string username); } 

and xml file sets mongodbfactory:

<!-- activate spring data mongodb repository support -->     <mongo:repositories base-package="com.mydata.repo.user" />      <!-- mongodb host -->     <mongo:mongo host="${mongo.host.name}" port="${mongo.host.port}" />     <mongo:db-factory dbname="${mongo.db.name}" />      <!-- template performing mongodb operations -->     <bean id="mongotemplate" class="org.springframework.data.mongodb.core.mongotemplate"         c:mongo-ref="mongo" c:databasename="${mongo.db.name}" /> 

make sure configure appropriate writeconcern on mongotemplate or mongodbfactory implementation.

the javadoc relevant mongotemplate method here, 1 simplemongodbfactory here.