transaction inside a for loop

Question

I want to run a transaction inside a for loop. My code is :-

 for(var i=0;i<len;i++){
      // some code

      alert('before transaction');

      var db = window.openDatabase("Database", "1.0", "Pin Point", 200000);
      db.transaction(fetchSubList, errorLists);  

      alert('after transaction');
  }


 function fetchSubList(tx) {  
    tx.executeSql('some QUERY', [], fetchSubListSuccess, errorLists);
  }


function fetchSubListSuccess(tx, results) {
  alert("fetchSubListSuccess()...");

  // some code
}

But the problem is that after the alert (before transaction) i directly get alert (after transaction) and only when the for loop ends then the transaction start....

I followed the this link to solve but still i'm not able to figure it out....

I don't think you should open many databases in the same for-loop — Bergi, Nov 08 '12 at 11:02
`db.transaction` takes a `successCallback` parameter, do the `after transaction` alert in there. — Barmar, Nov 08 '12 at 11:17
@Bergi yes i know its async... but how can i achieve this (i mean i want it to work as synchronous) — Aamir Shah, Nov 08 '12 at 11:39
@Barmar The 2 alerts keeps on coming one after the other based on the number of times the loop is running... But only after the loop has ended then the fetchSubList() function is called.... — Aamir Shah, Nov 08 '12 at 11:41
You could use the `DatabaseSync` API to get synchronous operations. — Barmar, Nov 08 '12 at 11:44
@Barmar do u mean var db = window.openDatabaseSync("Database", "1.0", "Pin Point", 200000); ..... well this gives me an error at console — Aamir Shah, Nov 08 '12 at 11:45
@Bergi callbacks.... can u explain how exactly can i use callbacks based on my requirements... — Aamir Shah, Nov 08 '12 at 11:46

score 1 · Accepted Answer · answered Dec 06 '12 at 08:43

It is not possible to do it... We need to refactor the code so that code looks like this :-

    db.transaction(function(tx) 
    {

      // some value
      var loop_limit = 10

      for(var i=0; i<loop_limit;i++ ){ // ITERATE HERE
        tx.executeSql(Statement, [],Sucess, error);
      }

    });

transaction inside a for loop

1 Answers1