Step 3: Handling Custom URL Parameters

In this step, we add the functionality to interpret URL parameters in our local mock server configuration.

We know that the OData provider of this service implements a URL parameter that returns only the first three entries of a set. So, for example, calling the URL with parameter/Meetups?first=3 should return only the first 3 meet-up entries instead of all available entries.

Preview

Figure 1: Only the next three meet-ups are shown

Coding

You can view and download all files in the Explored app in the Demo Kit under Mock Server - Step 3.

webapp/localService/mockserver.js

...
	jQuery.sap.require('sap.ui.core.util.MockServer');
	MockServer = sap.ui.require("sap/ui/core/util/MockServer");
	var oMockServer = new MockServer({rootUri : "/"});
	oMockServer.simulate("localService/metadata.xml", {
		sMockdataBaseUrl : "localService/mockdata",
		bGenerateMissingMockData : true
	});
	var fnCustom = function(oEvent) {
		var oXhr = oEvent.getParameter("oXhr");
		if (oXhr && oXhr.url.indexOf("first") > -1) {
			oEvent.getParameter("oFilteredData").results.splice(3, 100);
		}
	};
	oMockServer.attachAfter("GET", fnCustom, "Meetups");

       oMockServer.start();
...

In some scenarios, a server-specific implementation is used to calculate the returned data. For example, you can use a custom URL parameter that is typically interpreted by the server. The mock server ignores it, thus still returning the entire set of meet-ups.

In this tutorial, we use the URL parameter first=3 to fetch the first three entries. So, for example, calling to /Meetups?first=3 should return at most three meet-up entries.

However, since this is a custom parameter that is not part of the standard official OData query options, it will not get processed correctly by the mock server. Moreover, the mock server simply ignores it and return the entire set of meet-ups.

We now enable the functionality when running in mock mode. As its functionality corresponds to the OData $top system query, we simply evaluate it to $top at runtime.

First, we create a callback function that we later attach to every GET request made to the Meetups entity set of the service. Note that we choose the attachAfter event that is fired after the built-in request processing of the mock server. The event contains the actual XHR object and the mock data to be returned to the application. Inside the callback function we remove all results starting from third entry: The oFilteredData parameter comes with the event attachAfter and contains the mock data entries that are about to be returned in the response.

Second, we attach the callback to every GET request to the specific Meetups entity set.