knockout.js - using knockout to set css class with an if condition -

i want set bootstrap css class span if condition (up binded value). have isapproved field in list , want see field 'label-success' class when active , 'label-important' class when inactive

i added line , time taking first class :

data-bind="text: isapproved, css: isapproved = 'true' ? 'label label-important' : 'label label-important'" 

is possible in html or should add computed field on vm?

if understood right, binding looking for.

 data-bind="text: isapproved, css: {     'label' :  true,     'label-success' :  isapproved(),     'label-important':  !isapproved()  }" 

i hope helps.