Filtering LINQ Queries Using Business Rules Engine

// Global variable to hold reference to Web Rule
// (optional, just for the sake of convenience)
var webrule;

// Init everything on page load
$(function ()
{
	// Use Web Rule's global shortcut $ce to get reference to
	// the control by its server ID (not its client ID)
	webrule = $ce("filterControl");

	$("#ddlEntity").change(loadSettings);
	$("#ddlTheme").change(loadSettings);
	$("#chkHelp").click(loadSettings);
	$("#spnSearch").click(search);
	$("#spnClear").click(search);

	// Finally, get filter's settings
	loadSettings();
});

// Method that requests Web Rule UI settings from the
// server and initializes Web Rule
function loadSettings()
{
	clear();
	// Call the LoadSettings MVC action declared in the AjaxController to get the settings
	post("/LoadSettings", JSON.stringify({ entity: $("#ddlEntity option:selected").val(), theme: $("#ddlTheme option:selected").val(), help: $("#chkHelp").is(":checked")}), settingsLoaded);
};

function settingsLoaded(data)
{
	// Pass the received json string to Web Rule
	webrule.loadSettings(data);
};

function search()
{
	// Calls the search() server action and passes the search result to searched() function
	post("/Search", JSON.stringify({ entity: $("#ddlEntity option:selected").val(), clientData: webrule.extract() }), searched);
};

function searched(data)
{
	// Reset the grid
	var grid = $("#divGrid").html("");
	if (data.IsFilterEmpty)
	{
		// The filter is empty. Notify the user and do nothing
		$("#spnInfo").text("The filter is empty");
	}
	else if (!data.IsFilterValid)
	{
		// The filter is invalid. Notify the user (optionally) and pass the invalid data to Web Rule
		$("#spnInfo").text("The filter is invalid");
		webrule.loadInvalids(data.ClientInvalidData);
	}
	else
	{
		if (data.Records.length == 0)
		{
			// No matching records found
			$("#spnInfo").text("No records found");
		}
		else
		{
			// For all table haters out there: relax guys, it's a TABULAR data :)
			var tbl = document.createElement("TABLE"), row, cell, label, list;
			tbl.cellPadding = tbl.cellSpacing = tbl.border = 0;
			tbl.className = "filter";

			// headers
			row = tbl.insertRow(-1);
			for (var i in data.Headers)
			{
				label = data.Headers[i];
				cell = row.insertCell(-1);
				cell.className = "filterHeader";
				$(cell).text(label);
			}
			var alt = false;
			// Going through the records, constructing each record as a table row.
			for (var i in data.Records)
			{
				row = tbl.insertRow(-1);
				list = data.Records[i];
				row.className = alt ? "filterAltRow" : "filterRow";
				// Using headers as a counter, going through all records and constructing
				// each row by adding cells, where each cell represents a label in the record
				for (var j in data.Headers)
				{
					cell = row.insertCell(-1);
					cell.className = "filterCell";
					$(cell).text(list[j]);
				}
				alt = !alt;
			}
			// Finally, add the table to the grid's div container
			grid.append(tbl);
			$("#spnInfo").text(data.Records.length + " records found");
		}
	}
};

// Clears the Filter Area, removes the grid table and resets the info message
function clear()
{
	webrule.clear();
	$("#divGrid").html("");
	$("#spnInfo").text("Demo version. Search is delayed for 1 second.");
};

// Utility wrapper that handles HTTP posts to the server.
// jQuery is used here as an example; you can use any framework
// that wraps calls to XmlHttpRequest
function post(url, data, delegate)
{
	$.ajax({
		type: "POST",
		url: window.location.pathname + url,
		contentType: "application/json; charset=utf-8",
		dataType: "json",
		data: data,
		cache: false,
		success: delegate,
		error: error /*all errored calls will be delegated to the error() method declared below*/
	});
};

// Handler of errored server calls
function error(e)
{
	if (!e) throw Eror("Generic server error.");
	else
	{
		// We are using properties of the complex "e" error object to notify
		// the user about the error. This error handling has nothing
		// to do with Web Rule and exists here only for the sake of completeness.
		if (e.responseText)
		{
			$("#spnInfo").text("Server error");
			alert(e.responseText);
		}
		else throw Error(e);
	}
};