Force a value into NewForm.aspx

Question

I have a specific case where I want to hook up on the NewForm.aspx, hide a MultipleLookupField and set the value by myself.

I'm opening the NewForm.aspx with Javascript and using some query strings and I'm adding a custom class using AdditionalPageHead from an Elements.xml file:

<Control
Id="AdditionalPageHead"
ControlAssembly="$SharePoint.Project.AssemblyFullName$" ControlClass="MyNamespace.AdditionalPageHeadInjection"/>

Then I was able to set the value through code, but with the control visible. So the user still be able to change the value. If I try to hide the control, the value won't be set (null value) when saving.

I DO NOT want to override the NewForm.aspx, just be able to modify some NewForm.aspx controls behavior and visibility.

Answer 1

Assuming you're already have field control object (probably from SPContext.Current.FormContext?), you should use CssClass property to hide the control, rather than Visible property - because Visible property affects control server-side, so it will not be rendered at all.

Sample code:

(control as BaseFieldControl).CssClass = "s4-die";

s4-die class is from COREV4.CSS file, so it will be avaliable by default on all pages in SharePoint 2010. It is defined as follows:

.s4-die{
    display:none;
}

Update: Here is the screenshot which proves that FieldControlCollection items have CssClass property:

Full-sized image: https://i.stack.imgur.com/p6r1v.png

Update 2: Unfortunately, it turned out, that modifying the CssClass property doesn't affect MultipleLookupField control. Reflector analysis screenshot:

Hence, neither LookupField, nor MultipleLookupField use this property... :(

So the only acceptable approach left here, I reckon, is to stoop to client-side solution :( But at least we could use ClientID property rather than field title to reference the field control. Tentative javascript:

var clientId = '{0}_ctl00_MultiLookupPicker';
function hideMultiLookup()
{
   var x = document.getElementById(clientId).parentElement.parentElement.parentElement.style.display = 'none';
}
_spBodyOnLoadFunctionNames.push('hideMultiLookup');

Where {0} placeholder should be replaced with the actual client id (control.ClientID). In my case it was:

Note we need to add _ctl00_MultiLookupPicker to the control.ClientID, as it performed in the script sample.

I've tested the solution and it works in my environment.

Answer 2

Instead of hiding or disabling the field, you could use jQuery to hide the whole table row that contains that field. It'd be something like $("input[title='FieldName']").parent().parent().hide(); to grab the field, then navigate to the parent cell and row, and hide the row. Using hide() will append a style="display: none;" to the element, so it will still exist in the DOM, be completely scribtable, and be submitted normally--it just won't be viewable to the user.

Answer 3

Expanding on webdes03's jQuery suggestion, here's how you can access multiple lookup fields:

Assuming your field's display name is Field To Hide, you can use this:

$("nobr:contains('Field To Hide')").closest("tr").hide();

Let me know if you need more details or if you have trouble with this.

BTW - as omlin mentioned, if the field display name ever changes, this jQuery could break. But if you're working with a fairly stable environment where field renaming is unlikely, I don't see anything wrong with using the display name to access the DOM element this way. I could be the devil's advocate here and give a reason why using a Guid is a bad idea -- if you're keeping all of your code in source control, and you work with multiple tiers (development, validation, staging, production), you can't hard code Guids since they will vary from tier to tier. If you use display names and internal names, it's much easier to maintain IMHO.

Answer 4

This is something that you could use SPUtility.js for (full disclosure, this is an open source JavaScript library that I maintain). As @webdes03 mentions, you can use JavaScript to do this. SPUtility.js tries to make the field lookups, gets, and sets easier on the developer. For example:

SPUtility.GetSPField('Title').SetValue('Hello world!').MakeReadOnly();

Or, you can use Hide() to make the entire row go away.

Currently, it depends on Prototype.js (instead of jQuery) but the easiest way is to just upload your script files to a document library and put a content editor with your code on the page.

Or, if you prefer, feel free to browse the source code to see how I select to fields. :)