After reading the entire admin guide I haven’t found how to modify datatype in a field already available.
To be more specific, for the field ‘shipping_address_state’ I would like to modify its datatype from ‘TextField’ to a drop down field.
I can create a new field and hide the existing one, but is there a more elegant way of proceeding?
In the case of Address fields, you will find there is some extra complexity to it, because there are several places in the code that reference these fields (pull them together to show a complete address, or in a feature that copies address from Account to Contact, etc).
just try to make that field a dropdown in the Edit view, editing metadata if necessary
make a new field that is a Dropdown. Hide the old field in the views. Then add a Workflow that, whenever the new field is changed, copies the value into the old field. This ensures that those other features I mentioned keep working.
I am a couple years to late to your question, but I have just done such a thing to a different datatype. I was able to change a “Decimal” into a “Integer”