I have a spring form with having backing object for it. The form is like this-
The error you are getting is correct as landingPageModels is a list. You would need to use index access like this landingPageModels[0].landingPage.url. If you have dynamic number of input/url, then you can use to create dynamic input variable names
landingPageModels
landingPageModels[0].landingPage.url