why does the ReadOnlyField hide the field in forms?

Question

i have a field that i want to make not editable for the users. its a field of type text.

I have a read about doing it with javascript and content editor webbpart, but i want to do it programmatically because the field is part of my Feature.

i have tried this code, but it hides the field in forms view.

SPList list = web.lists["caseslist"]; 
SPField field = list.Fields.GetField("casenumbers"); 
field.ReadOnlyField = true; 
field.ShowInDisplayForm = true; 
field.ShowInEditForm = true; 
field.ShowInNewForm = true; 
field.Update(); 

what are iam doing wrong, why does this code hide the field in the forms? Iam not sure but is it possible to make a field "non editable" programmatically?

Answer 1

If you make field readonly it will not be displayed on edit or new forms. You can do it with custom form only. There are not needs to use JS-code, you can do it with xslt but in custom form only. But you can deploy this form with your feature.

Answer 2

    My code: 

        <SCRIPT language=javascript> 
        function DisableField(title) {
        for(var i = 0; i < document.all.length; i++) {
        var el = document.all[i]; 
        if(el.title == title) 
        {
        el.disabled = true; 
        break; 
        }
     }

   }
       DisableField("casenumber"); 
    </SCRIPT>

As mentioned this code works for my fields, except the Person or Group field.

Sorry but i dont understand how to package this and deploy it with my feature?

thanks for you replys its really helpful.