Web services are hot. I may write a jQuery plugin to talk to SP web services at some point, but first I wanted to do something novel, write a JavaScript tool that can fetch list data using the RPC method (specifically the URL protocol).

Who Wants This?

Anyone developing solutions around List View web parts may find this helpful. A common request from users involves performing various math functions on calculated columns. OOB, SP does not do this which lead me to develop code like Total Calculated Columns.

Better Than DOM Walking?

The DOM walking technique I used previously works but has limitations. Pulling data out of the rendered HTML comes with a set of problems. First, since we read the DOM for data, we can only include rendered records. Records inside closed groups have not loaded and therefore cause errors in the calculations. Second, these scripts are fragile because the DOM can change. Users often have the ability to move (or remove) columns.

Better Than Web Services?

I would argue that the RPC method performs better than web services, but I don’t have any data to support that (yet). I know that the server caches responses to RPC requests and the web parts on the page have already performed the same request. So, we should get a response in the shortest time possible (about 110 ms on my test site).

The power of web services makes some admins nervous. If your server admins have taken precautions to limit or inhibit web services, owssvr.dll will still be an option–it must be because of the way SP works under the hood.

Lastly, through some hacks, owssvr.dll can do some tricks web services can not. For instance, fetching all items in a discussion list (folders/threads and messages/posts), as far as I know, can only be done with the RPC method.

Web services still holds one significant advantage over RPC, the ability to request a list by name. RPC must use the GUID.

Click “Read more…” to get the code and documentation:

Some Documentation

I created several helper functions which are part of the ows object. Each has a usage example in the myCb() callback function at the bottom.

When creating the ows object, the default settings will get the list and view GUIDs from the ctx object on the page. If there is more than one web part, the default settings use the ctx object for the first web part added to the page (not the first appearing in the DOM). To get the correct ctxId for a web part by name, see my other article.

If you specify a custom ctx, you will need to supply the list and view members of the options argument (see last example).

• $.fn.ows(options,callback) – creates the ows object and returns an optional callback function with the modified options argument
• ows.getName(ctx,rsname) – Takes the web part context (can be derived from the options argument if used in the callback) and a column by its display name and returns the ows field name (ows_)
• ows.getNumber(ctx,rsname) – Takes the web part context and a column’s display name and returns the order number assigned to the field in the schema
• ows.getValues(ctx,rsname) – Takes the web part context and a column’s display name and returns defined values found in the ows data
• ows.getAll(ctx,rsname) – Takes the web part context and a column’s display name and returns all values from the ows data
• ows.getSum(ctx,rsname) – Takes the web part context and a column’s display name and returns a sum of numerical, defined data
• ows.getAvg(ctx,rsname) - Takes the web part context and a column’s display name and returns an average of defined values
• ows.getMax(ctx,rsname) – Takes the web part context and a column’s display name and returns the maximum value
• ows.getMin(ctx,rsname) – Takes the web part context and a column’s display name and returns the minimum value
• ows.getTable(ctx) – Takes the web part context and returns the web part’s main table as a jQuery object
• ows.getPosition(ctx,rsname) – Takes the web part context and a column’s display name and returns the order number – 1 (same as number but base 0)

<script type="text/javascript">
//?PageView=Shared&ToolPaneView=2
if(typeof jQuery=="undefined"){
	var jQPath="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/";
	document.write("<script src='",jQPath,"jquery.min.js' type='text/javascript'><\/script>");
}
</script>
<script type="text/javascript">
(function(){
	Array.max = function(array){
		return Math.max.apply( Math, array );
	};
	Array.min = function(array){
		return Math.min.apply( Math, array );
	};
	var defaults = {
		ctx: "ctx1",
		baseUrl: "",
		list: "",
		view: "",
		command: ""
	},
	isNumber = function(val){
		return (/^-?((\d+\.?\d*)|(\.\d+))$/).test(val);
	},
	ows_url = function(o){
		o.baseUrl = (!o.baseUrl)?L_Menu_BaseUrl:o.baseUrl;
		o.list = (!o.list)?window[o.ctx].listName:o.list;
		o.view = (!o.view)?window[o.ctx].view:o.view;
		return o.baseUrl+"/_vti_bin/owssvr.dll?XMLDATA=1&List="+
				o.list+"&View="+o.view+o.command;
	},
	create_ows = function(){
		ows = {
			getName : function(ctx,rsname){
				var n = $.grep($(ows[ctx].schema),function(e,i){
					return ($(e).attr("rs:name")==rsname);
				});
				return $(n).attr("name");
			},
			getNumber : function(ctx,rsname){
				var r = $.grep($(ows[ctx].schema),function(e,i){
					return ($(e).attr("rs:name")==rsname);
				});
				return $(r).attr("rs:number");
			},
			getPosition : function(ctx,rsname){
				var pos = ows.getNumber(ctx,rsname);
				return parseInt(pos)-1;
			},
			getValues : function(ctx,rsname){
				var v = [],
					vname = ows.getName(ctx,rsname);
				$(ows[ctx].data).each(function(i,e){
					var vx = $(e).attr(vname);
					if(vx){
						v.push(vx);
					}
				});
				return v;
			},
			getAll : function(ctx,rsname){
				var a = [],
					aname = ows.getName(ctx,rsname);
				$(ows[ctx].data).each(function(i,e){
					a.push($(e).attr(aname));
				});
				return a;
			},
			getSum : function(ctx,rsname){
				var svals = ows.getValues(ctx,rsname),
					sum=0;
				$(svals).each(function(i,e){
					if(e && isNumber(e)){
						sum += parseFloat(e);
					}
				});
				return sum;
			},
			getAvg : function(ctx,rsname){
				var avgsum = ows.getSum(ctx,rsname),
					avgcount = ows.getValues(ctx,rsname).length;
				return avgsum/avgcount;
			},
			getMax : function(ctx,rsname){
				var xvals = ows.getValues(ctx,rsname);
				xvals = $.grep(xvals,function(e,i){
					return (e && isNumber(e));
				});
				return Array.max(xvals);
			},
			getMin : function(ctx,rsname){
				var nvals = ows.getValues(ctx,rsname);
				nvals = $.grep(nvals,function(e,i){
					return (e && isNumber(e));
				});
				return Array.min(nvals);
			},
			getTable : function(ctx){
				var t = $("[id='"+window[ctx].listName+"-"+window[ctx].view+"']");
				return t;
			}
		};
	};
	jQuery.fn.ows = function(options,callback){
		var o = $.extend({},defaults,options);
		if(typeof ows=='undefined'){create_ows();}
		$.get(ows_url(o),function(data){
			ows[o.ctx] = {
				schema:$(data).find("[nodeName='s:AttributeType']"),
				data:$(data).find("[nodeName='z:row']")
			};
			return callback(o);
		});
	};
})();
$(function(){
	var myCb = function(o){
		var name = ows.getName(o.ctx,'% Complete');
		//console.log(name);
		var num = ows.getNumber(o.ctx,'% Complete');
		//console.log(num);
		var vals = ows.getValues(o.ctx,'% Complete');
		//console.log(vals);
		var all = ows.getAll(o.ctx,'% Complete');
		//console.log(all);
		var sum = ows.getSum(o.ctx,'% Complete');
		//console.log(sum);
		var count = ows[o.ctx].data.length;
		//console.log(count);
		var avg = ows.getAvg(o.ctx,'% Complete');
		//console.log(avg);
		var max = ows.getMax(o.ctx,'% Complete');
		//console.log(max);
		var min = ows.getMin(o.ctx,'% Complete');
		//console.log(min);
		var t = ows.getTable(o.ctx);
		//console.log(t);
		var pos = ows.getPosition(o.ctx,'% Complete');
		//console.log(pos);
	};
	//this example builds the ows object for the default web part and runs a callback function myCb
	//$.fn.ows({},myCb); 

	//this example builds the ows object for the default web part
	//$.fn.ows();

	//this example specifies the web part to use and uses an inline callback function
	$.fn.ows({ctx:'ctx1'},function(o){
		console.log(ows.getValues('ctx1','ows_PercentComplete'));
	});

	//this example specifies the list and view which does not need the web part on the page
	//$.fn.ows({ctx:"custom", list:"{730166FA-800A-4514-8912-AF49C681DF94}", view:"{2AB283B2-7B67-44AF-BC2E-304ACEED2035}"},myCb);
});
</script>

Thanks to John Resig for the min/max function idea.