Default null value to a required Lookup Column

Question

The title pretty well speaks for what I need. I have a lookup column on a list, getting data from a custom existing site column i created.

I need it be null by default so they get an error if they don't choose something, but the column must stay as Required.

Answer 1

Not possible really as such, particularly if you make it Required. But as alternative you should rather add a so called "0 option" and using an CEWP in the page you could use ECMA script to ensure validation using something like a jQuery library.

1. First we need jQuery JavaScript library and the jQuery Validation Plugin.
2. 2.Upload the validation plug-in into any library in your SharePoint site.
3. Next, open the SharePoint Site and edit the list’s NewForm.aspx or EditForm.aspx in SharePoint Designer in Advanced Edit mode and go from there.

Example

• http://sharepointchronicles.com/2011/11/using-jquery-to-simplify-your-forms/
• http://ratikantas.blogspot.ch/2013/01/sharepoint-jquery-form-validation.html http://markviky.blogspot.ch/2012/04/validation-before-save-in-new-or-edit.html

Answer 2

It's not possible by default. But a small Javascript will do the trick...

addDefaultValues = function() {
    $("select[title$='Required Field']").each(function(){
        $(this).prepend('<option value="">(none)</option>');
    });
}