Usability improvement: Do not offer to create a new field in the field calculator dialog

[tschmetzer]

Confusing: Create a new field in the field calculator dialog:
The option exists even without being in edit mode on the layer and the user cannot create a new field
-> suggestion to not offer the field creation from the field calculator dialog and have only the option to create virtual fields as a remaining option

A different approach could be to offer the switching to edit mode.

[gioman]

I don't get this. It pretty much established that in the FC a user could 1) update a field 2) compute values into a new field virtual or not.

[benwirf]

I don't really understand this issue either. If you open the field calculator for a layer which is not in edit mode, you should see this message at the bottom of the FC dialog:

After entering the required inputs and a valid expression, you can click 'OK' and edit mode will be automatically turned on. This is the case regardless of which option is selected. I personally would not be in favor of removing the 'Create a new field' option.

[andreasneumann]

I think this issue should be closed. Everything works as expected and I don't see a reason to change this behavior.

[tschmetzer]

Thanks for taking the time. There are several things in this dialog:

• "Create a new field" and "Update existing field" are "either ... or ..." options which I understand can never coexist. Neither of the two options can be deselected. The user is confused that check boxes instead of radio buttons are used to indicate this.

• Either I never read the docs about this dialog or it must have been a while ago but I assumed the option "Create a new field" just creates a new field whereas the virtual would create a new field with entries dependant on the expression. So when trying to create a new field on a layer not in edit mode I assumed a bug as I was unable to hit "OK".
  Consulting the docs clears up why I was unable to do so. I totally didn't understand the idea and function this dialog has to offer. To overcome other users feeling tempted to misleadingly interpret the "Create a new field" as such I would suggest to extend that text to "Create a new field with values based on expression/function" or something similar. I'm pretty sure many (maybe rather not extremely experienced) users have already at least stumbled upon thinking they could just create a new field here.

• "Create virtual field" could be extended to a more meaningful text like "Create virtual field with instant calculation". This is more self-explanatory and the user might not be trapped into trying to create a new (whatever virtual) field and not being able to click "OK"

• In order to avoid users to accidentally click "OK" without having read and understood the informational text at the bottom I could think of:
  Instead of the informational "i" symbol at the left hand side a layer edit button could be placed to actively require the user to turn on layer editing befor hitting OK. That assures the user has read and understood what he's agreeing on.

[gioman]

* could be placed to actively require the user to turn on layer editing befor hitting OK

@benwirf this was the (very) old behavior in QGIS and it was changed as it is now on purpose.

for the other points, feel free to open separate feature requests/suggestions for improvements.

Closing?

[tschmetzer]

As a follow-up I created the tickets:
#41730
#41731
#41732

From my perspective the ticket can be closed now.