Lister: available fields not updating correctly after changing template filter

[Toutouwai]

Short description of the issue

When a template filter is applied in the core Lister (Find), the list of fields available in subsequent filter rows is updated so that only fields contained in the selected template are available.

That sounds like it would be a useful feature, but the problem is that if the template filter is changed to a different template the selection of fields available in the dropdown is not updated properly, and sometimes no fields are available for selection at all.

Fields in the basic-page template:

Fields in the test-lister template:

Fields available for selection (so far, so good):

But notice what happens when the template selection is changed from "basic-page" to "test-lister". The fields in the test-lister template are not available for selection.

Expected behavior

The available fields stay synchronised with the selected template.

Setup/Environment

• ProcessWire version: 3.0.141

[ryancramerdesign]

@Toutouwai Rows that are already present in the InputfieldSelector are not modified by changes in InputfieldSelector (like changing the template). You would have to add a new row (by clicking "Add Filter") in order to see fields that are specific to a new template selection.

[Toutouwai]

Rows that are already present in the InputfieldSelector are not modified by changes in InputfieldSelector (like changing the template).

That's basically the issue I'm describing here :-)

The "Template" and "Title" filter rows are present in the core Lister by default, so it's very likely that users are going to use/modify those rows rather than add new rows.

And the existing rows do modify each other, just not in a way that's consistent. So with the two default rows, on the first setting of "Template" the available fields in the "Title" dropdown are modified - only fields present in the selected Template are available for selection. On a subsequent setting of Template the available fields in the Title dropdown are modified again, but this time there are no fields available for selection (or it's at least possible for this to happen). This is quite bad from the user's point of view because now the Lister seems to be unusable for them - most of the time the user will want to filter on a field value and I don't think it will occur to them that they have to add a new row rather than use an existing row.

I haven't looked into what's causing the issue, but I'm guessing that each time the template changes some options that represent fields are removed from other dropdowns. This works as expected when the dropdown contains all the field options, but if some options have already been removed from a dropdown then it doesn't work as expected. So rather than only removing existing options it seems that the options need to be rebuilt from some list of all fields, so that it's possible for options to be added as well as removed.

[teppokoivula]

The "Template" and "Title" filter rows are present in the core Lister by default, so it's very likely that users are going to use/modify those rows rather than add new rows.

Just a quick note from the sidelines: that's what I've always done. I'd also say that this is a common scenario, and (though I hadn't even realised that it doesn't work as expected, probably because I don't use Lister that much) current behaviour does sound a bit unexpected.