Question: How To Create A Sugar Logic Formula For AutoIncrement Field

As André said a logic hook is the best solution.

It is actually a very simple logic hook (this code is not tested or verified, so take it with a pinch of salt, but it should get you started on the right track):

in the module's directory create a logic hook file, let's call it NameYourClass_Logic.php

class NameYourClass_Logic {

  //before_save
  //this before_save function allows us to see if the value of the Name in Field1 has changed, in which case we want to update Field3
  //the fetched_row array contains the values of the fields before the change is made, IF this is not a new record.
  //if this is a new record then $bean->fetched_row is empty and this will not run, we take care of the new records in the after save
  //where we check if field3 is empty and set it with the newly assigned name in field1 incremental value from field2 

  function updateField3 ($bean, $event, $arguments){
     if (isset($bean->fetched_row) && $bean->fetched_row["field3"] != $bean->field3) {
      $bean->field3 = $bean->field1 . '- ' . $bean->field2;
      //do NOT save a bean in the before save, this code executes before the save so it just sets the field which will be saved
    }
  }

  //after save

  function setField3 ($bean, $event, $arguments) {
    //check if Field3 is empty, if it is already populated we don't need to do it again, this will also avoid infinite loops 
    //if you save a bean in an after save the save will trigger a before save and an after save again so you need to have a way to stop it
    //the if statement will stop this hook from executing if field3 is already populated

    if (empty($bean->field3) && !empty(field1) && !empty(field2) || ){
        $bean->field3 = $bean->field1 . '- ' . $bean->field2;
        $bean->save(); //here you have to save explicitly, this is an after-save hook
    }
  }

in the module's directory, add or edit your logic_hooks.php file to list these two logic hooks:

// Do not store anything in this file that is not part of the array or the hook version. 
//This file will be automatically rebuilt in the future. 

$hook_version = 1;
$hook_array = Array();

$hook_array['before_save'] = Array();
$hook_array['before_save'][] = Array(1,'updateField3','custom/modules/YourModule/NameYourClass_Logic.php','NameYourClass_Logic','updateField3',);

$hook_array['after_save'] = Array();
$hook_array['after_save'][] = Array(1,'setField3','custom/modules/YourModule/NameYourClass_Logic.php','NameYourClass_Logic','setField3',);

I hope this helps you get going and more interested in building your own logic hooks, if you are not already doing so :)

FrancescaS

As André said a logic hook is the best solution.

It is actually a very simple logic hook (this code is not tested or verified, so take it with a pinch of salt, but it should get you started on the right track):

in the module's directory create a logic hook file, let's call it NameYourClass_Logic.php

class NameYourClass_Logic {

  //before_save
  //this before_save function allows us to see if the value of the Name in Field1 has changed, in which case we want to update Field3
  //the fetched_row array contains the values of the fields before the change is made, IF this is not a new record.
  //if this is a new record then $bean->fetched_row is empty and this will not run, we take care of the new records in the after save
  //where we check if field3 is empty and set it with the newly assigned name in field1 incremental value from field2 

  function updateField3 ($bean, $event, $arguments){
     if (isset($bean->fetched_row) && $bean->fetched_row["field3"] != $bean->field3) {
      $bean->field3 = $bean->field1 . '- ' . $bean->field2;
      //do NOT save a bean in the before save, this code executes before the save so it just sets the field which will be saved
    }
  }

  //after save

  function setField3 ($bean, $event, $arguments) {
    //check if Field3 is empty, if it is already populated we don't need to do it again, this will also avoid infinite loops 
    //if you save a bean in an after save the save will trigger a before save and an after save again so you need to have a way to stop it
    //the if statement will stop this hook from executing if field3 is already populated

    if (empty($bean->field3) && !empty(field1) && !empty(field2) || ){
        $bean->field3 = $bean->field1 . '- ' . $bean->field2;
        $bean->save(); //here you have to save explicitly, this is an after-save hook
    }
  }

in the module's directory, add or edit your logic_hooks.php file to list these two logic hooks:

// Do not store anything in this file that is not part of the array or the hook version. 
//This file will be automatically rebuilt in the future. 

$hook_version = 1;
$hook_array = Array();

$hook_array['before_save'] = Array();
$hook_array['before_save'][] = Array(1,'updateField3','custom/modules/YourModule/NameYourClass_Logic.php','NameYourClass_Logic','updateField3',);

$hook_array['after_save'] = Array();
$hook_array['after_save'][] = Array(1,'setField3','custom/modules/YourModule/NameYourClass_Logic.php','NameYourClass_Logic','setField3',);

I hope this helps you get going and more interested in building your own logic hooks, if you are not already doing so :)

FrancescaS