I want to use ModelBuilder to dissolve polygons by a field whose values are concatenated strings based on 3 other fields. The general process is this:
Add field, type string, called "concat". Field calculate that field to be [field1]&""&[field2]&""&[field3]. Dissolve polygons by field "concat".
However, I want to make field1, field2, and field3 user defined. How can I do this? In the field calculate box I can pick the three fields I want but these three fields could be different on another dataset. So when running the tool I want the user to be able to pick the polygon dataset, pick the three fields for the dissolve, then hit go.