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minciminci 

Another Batch Apex issue: class members.

I wrote somthing like this to check the way class fields are

behaving in Batch apex:

This code counts number of times execute method was called

For my surprise I saw that I get only 1 in the debug logs!

 

Code:

global class To_Bach implements Batchable{

 

global Integer _i;

 

global Bach(){

   _i = 0;

}

 

global

 

global void execute(){

   _i++;

   System.debug('times visited '+i);

}  

 

}

 

SO! How thies field behave?

What am I missing?

Thanks!

grigri9grigri9

By default each execution of a batch apex job is considered a discrete transaction. To maintain state across transactions you have to declare the class as database.stateful. 

 

I.E.

 

 

global class To_Bach implements Database.Batchable<sObject>, Database.Stateful{

   global integer i;
   global final string query;
   global To_Bach(string q){
     i = 0;
     query = q;
   }

   global Database.QueryLocator start(Database.BatchableContext BC){
      return Database.getQueryLocator(query);
   }
   
   global void execute(Database.BatchableContext BC, List<sObject> scope){
      i++;
      system.debug('times visited: '+i);
   }

global void finish(Database.BatchableContext BC){
   }
}