This works for D7
Term reference field (autocomplete?)
in rules, widget does not affect, you just set values, but leave it as autocomplete, a select list cosumes more resourses
The Text field is old and already has 500 nodes with 500 unique values.
Unique values, this means one unique taxonomy term for each node.
The Term reference field is new and needs to contain same data.
Your taxonomy term title value it will hold the field value
Your events on node: new/update are ok
On your conditions i can't tell mutch, img is not complete, i sugest to include 'field data value IS empty' on your node taxonomy term rerefence field. This will avoid to create duplicate terms and updating same node twice.
Steps:
1.- In actions secction add an accion
2.- create a new entity (term must exist to be assigned as TR to a node by rules)
3.- select from dropdown: taxonomy term
4.- for term name select node title, avilable in data selector mode
5.- select your taxonomy vocavulary
6.- change (optional) variable name and hit save
7.- add another accion: save entity, the new term
8.- add aonther accion: set a data value
9.- now select your updated node and drill down to find term reference field
10.- and set node field value with the term reference you just created
11.- save node, done
EDIT:
Steps to buit a component:
this way you can call it from node/new event or from a VBO to update all old nodes
a.- add a component of type RULE
b.- in parameters seccion add parameter type: node, label: product node, machine name:product_node, save settings
c.- on conditions add: entity has field (your product node): select your term reference field
d.- add another condition: your term reference field is empty
do all accions steps explainded above in rule, now you can call your component any where.
