<paper-input-decorator label="test" autoValidate?="{{autoValidate}}">

[gertcuykens]

<paper-input-decorator label="Firstname" autoValidate?="{{autoValidate}}">
       <core-localstorage name="firstname" value="{{firstname}}"></core-localstorage>
       <input name="firstname" value="{{firstname}}" is="core-input" required>
</paper-input-decorator>

On submit I do this

this.autoValidate=true
if (this.$.myfrm.checkValidity()) this.$.myfrm.submit();

But autoValidate?="{{autoValidate}} does not work? It does work when for example use hidden?="{{autoValidate}} instead of autoValidate

[gertcuykens]

Nevermind I found more information how to do this in the documentation of paper-input-decorator