Getting all selected checkboxes from a FormCollection

Question

I have a form which contains a whole bunch of checkboxes and some other types of control too. I need to retrieve the names of each selected checkbox.

What is the bes

Answer 1

Unfortunately that type of information isn't available in the collection. However if you prepend all your checkboxes with something like <input type='checkbox' name='checkbox_somevalue' /> then you can run a query like

var names = formCollection.AllKeys.Where(c => c.StartsWith("checkbox"));

Since only the checked values will be posted back you don't need to validate that they're checked.

Here's one that grabs only checked values

var names = formCollection.AllKeys.Where(c => c.StartsWith("test") && 
                        formCollection.GetValue(c) != null &&
                        formCollection.GetValue(c).AttemptedValue == "1");

Answer 2

This is one of the old questions not active for years but I stumbled on it. My problem was that I have an array of check boxes - let's say the name is 'IsValid' and wanted to get the status of each of the check boxes (my project was in MVC 5). On form submit i did the loop of form collection and got the values as...

if (key.Contains("IsValid"))
                    sV = (string[])collection.GetValue(key.ToString()).RawValue;

Since on form post the hidden field value was also posted with the checked check boxes; the array contained one additional value of 'false' for ONLY checked check box. To get rid of those i used following function; I hope that it helps somebody and if my approach is wrong then a better solution would be helpful to me as well!

sV = FixCheckBoxValue(sV);

        private string[] FixCheckBoxValue(string[] sV)
    {
        var iArrayList = new List<string>(sV);

        for (int i = 0; i < iArrayList.Count; i++)
        {
            if (iArrayList[i].ToString() == "true")
            {
                iArrayList.RemoveAt(i + 1);
            }                
        }
        return iArrayList.ToArray();
    }