QGIS show only selected polygons on the map

Question

I would like to make visible only these polygons, which are selected right now.

I tried to go with this hint:

Displaying only selected features on map in QGIS

but when in my expression I applied:

   is_selected('Preferred cell radius')

I got an error:

Cannot convert to feature

I tried to solve it by looking at this issue:

QGIS expression "get_feature" will not evaluate feature, when called within "is_selected"

by adding up three columns from my data attribute table:

   is_selected("Preferred cell radius", get_feature("Name", "descriptio", "new_name"))

but in this case, I have another error:

Eval error: Column 'Preferred cell radius' not found

There is also another option in the Atlas features

QGIS Atlas: Only Show Selected Feature

but it looks like I have to add the certain feature ID

How can I make only these items visible, which are already selected?

From the answer below I have situation soch as this:

I have selected an object by the attribute table. Now instead of the style defined with is_selected() I have the selection color set in the project. How to apply the individual style for this selection?

Answer 1

is_selected() expects a feature as input: is_selected(<the_feature>). If left empty, it uses the current feature, you could also write as is_selected($currentfeature). You can also reference a layer: is_selected(<the_layer>,<the_feature>)

You give a string 'Preferred cell radius' or a field "Preferred cell radius" to it, thats where these errors come from. Either use it as:

is_selected()

or

is_selected(layer,get_feature(layer,attribute,value))

In your case the first option combined with a rule based symbology should do it. If the features are related to another layer you do the selection in, the second one should be what you are looking for.