R – Sharepoint event handling.. which column changed

event handlingsharepoint

I'm writing an event handler to handle the updating of a particular SPItem in a list. The event is asynchronous and I get the SPEvenItemProperties without a problem. What I would like to find out is which of the SPItems columns' actually fired the event. Anyone have any idea how?

Thanks in advance.

Best Answer

Your answer depends a bit on from where and how the SPListItem is retrieved. In a regular list, you do not have access to the previous values of the item. If you turn on versioning, you can get access to the previous versions, depending on permissions, of course.

For a document library you can use the SPItemEventProperties.BeforeProperties to get the previous metadata for a document.

For a document library you can try something like this:

foreach (DictionaryEntry key in properties.BeforeProperties)
{
    string beforeKey = (string)key.Key;
    string beforeValue = key.Value.ToString();

    string afterValue = "";
    if (properties.AfterProperties[beforeKey] != null)
    {
        afterValue = properties.AfterProperties[beforeKey].ToString();
        if (afterValue != beforeValue)
        {
            // Changed...
        }
    }
}

Related Solutions

Javascript – How to debug JavaScript / jQuery event bindings with Firebug or similar tools

See How to find event listeners on a DOM node.

In a nutshell, assuming at some point an event handler is attached to your element (eg): $('#foo').click(function() { console.log('clicked!') });

You inspect it like so:

jQuery 1.3.x

var clickEvents = $('#foo').data("events").click;
jQuery.each(clickEvents, function(key, value) {
  console.log(value) // prints "function() { console.log('clicked!') }"
})

jQuery 1.4.x

var clickEvents = $('#foo').data("events").click;
jQuery.each(clickEvents, function(key, handlerObj) {
  console.log(handlerObj.handler) // prints "function() { console.log('clicked!') }"
})

See jQuery.fn.data (where jQuery stores your handler internally).

jQuery 1.8.x

var clickEvents = $._data($('#foo')[0], "events").click;
jQuery.each(clickEvents, function(key, handlerObj) {
  console.log(handlerObj.handler) // prints "function() { console.log('clicked!') }"
})

Asp – How to update page data after event handling

Page events such as Init and Load will always fire before the event handler that raised the postback. This is the basis of the Page lifecycle (For a visual representation by Peter Bromberg, see here). Most developers new to ASP.NET have a major problem understanding and appropriately handling this "quandary".

The ideal way to do this is:

a. Your Page_Init should call a procedure (let's call it BindData() for illustration) that handles the creation of the table based on database data. This method would be similar to a binding method that binds to the database data and renders UI elements on the basis of that binding. IOW, you should remove the table creation code from the Page_Init method and put it in a separate method so that it can be called when needed.

Important note: This BindData() method also handles the attaching of the eventhandler for the dynamically created ImageButton control to the control. We'll call this ImageButton_Click. This is crucial for the control to the event to fire on subsequent postback.

b. When your ImageButton_Click method executes, it calls the BindData() method to recreate the table and it's bindings but with new sort order rules.

So, the order of execution on first load is:

Page_Init
BindData()

The order of execution on subsequent loads (on postback) is:

Page_Init
BindData() - Eventhandler for ImageButton attached.
ImageButton_Click
BindData()

Best Answer

Related Solutions

Javascript – How to debug JavaScript / jQuery event bindings with Firebug or similar tools

Asp – How to update page data after event handling

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