Text input field with resizable part?

Question

User interface

There is a form, one of its fields is an identifier, part of which is entered manually, and part (serial number) is generated automatically after a request to the database. Since the automatically generated part is not at the end or beginning of the text, the question arises how best to implement such a field. So far, two solutions have come to my mind:

Which of the two, in your opinion, is better, and why? Perhaps there are better ways?

Answer 1

I believe that if part of the field is generated, and the user does not have to enter it himself, then she has nothing to do in the field to fill. Inevitably, there will be attempts to type it, correct it, etc. The second option is more preferable, but instead of the second text field, put a select (provided that there are several dozen options), because It is more convenient to select with the mouse than to write with capslock.
Even in this context, it is difficult to understand what kind of form it is, but if the user cannot influence this identifier, maybe it should be completely removed from the list of fields? Well, there somewhere in the corner to show it.

Answer 2

You can make this ID be dragged to the input. Its behavior inside the input should be similar to the behavior of a regular character. For example, as in iStatMenus:

How to drag it there

Answer 3

For a person who is closer to technology and computers, the first option is more obvious and easier.
For the end inexperienced user, I don’t even know. I am still looking for the ideal interaction in such complex systems.
If we consider specifically your two options, the first is preferable. The second is more difficult to perceive and only more confusing. Even I did not immediately understand what was what.

Answer 4

Forcing people to enter these OMG-3432723482 by hand looks like a mockery, provokes errors, reduces operator productivity and causes losses to the employer (well, ok, I went too far here). This cipher means something (document type, product type, material) - so make a choice of product types (through a dropdown with a fuzzy search, like VKontakte, and it would be nice with pictures) and let him substitute the necessary codes.
Coming up with some incomprehensible formats with questions, you create inconvenience. These codes are information for machines, not for people. Let the piece of iron remember these codes, for this it is made, and the person is engaged in more important things.
Oh, sorry, you didn’t show the whole form, I have a feeling that you have 20 more fields of the same there.