Itemupdating event receiver
You can then use an event receiver to set the location based on your custom location in Item Adding and Item Updating.
Create an additional location column which has its type set to choice and then add all the desired locations.
When creating an event from a calendar you can usually only use a text box to specify the location of an event. Use the “Set Field in Current Item” action in the workflow.
This is because the location column is sealed and you cannot change the field type of this column. Please note that if you use the Calendar E-Mail Extension and enter attendees when scheduling the event, these attendees will receive two invitations.
Then click next: Finally, choose the Type of receiver you want to create, what event you would like to hook up and to what type. You can then base the location column on your custom location column using a Share Point designer workflow that runs when an item is created or changed. For this option you also need to create an additional location column which has its type set to choice and then add all the desired locations.section to the field and hardcode the various Id’s that define a term set (required if you are using a sandboxed solution), or configure these in code.
I’m taking the code approach here as it is the only way to ensure the field will work across multiple environments.
These fresh events are intended to meet up the requirements and for better elasticity.