Abstracting the interpretation of MVC checkboxes values received by the FormsCollection object
- by Simon_Weaver
In ASP.NET MVC a checkbox is generated by the HtmlHelper code here:
<%= Html.CheckBox("List_" + mailingList.Key, true) %>
as this HTML:
<input id="List_NEW_PRODUCTS" name="List_NEW_PRODUCTS" type="checkbox" value="true" />
<input name="List_NEW_PRODUCTS" type="hidden" value="false" />
In case you're wondering why is there an extra hidden field? - then read this. Its definitely a solution that makes you first think 'hmmmmm' but then you realize its a pretty elegant one.
The problem I have is when I'm trying to parse the data on the backend. Well its not so much of a problem as a concern if anything in future were to change in the framework.
If I'm using the built in binding everything is great - its all done for me. But in my case I'm dynamically generating checkboxes with unknown names and no corresponding properties in my model.
So i end up having to write code like this :
if (forms["List_RETAIL_NOTIFICATION"] == "true,false") {
}
or this:
if (forms.GetValues("List_RETAIL_NOTIFICATION")[0] == "true") {
}
Both of which i still look at and cringe - especially since theres no guarantee this will always be the return value. I'm wondering if theres a way to access the layer of abstraction used by the model binders - or if I'm stuck with my controller 'knowing' this much about HTTP POST hacks.
Yes I'm maybe being a little picky - but perhaps theres a better clever way using the model binders that I can employ to read dynamically created checkbox parameters.
In addition i was hoping this this post might help others searcheing for : "true,false". Even though I knew why it does this I just forgot and it took me a little while to realize 'duh'.
FYI: I tried another few things, and this is what I found :
forms["List_RETAIL_NOTIFICATION"] evaluates to "true,false"
forms.GetValues("List_RETAIL_NOTIFICATION")[0] evaluates to "true"
(forms.GetValue("List_RETAIL_NOTIFICATION").RawValue as string[])[0] evaluates to "true"
forms.GetValues("List_RETAIL_NOTIFICATION").FirstOrDefault() evaluates to "true"
