Custom Search with Azure Mobile Services in JavaScript

I’ve published my first little Windows 8 app using the Azure Mobile Services in JavaScript. It was incredibly quick to get up and running and more flexible than I thought it would.

The one thing that was tricky was that I’m using JavaScript/HTML5 to build my app and since I don’t have Linq in JavaScript, doing a custom date search was difficult. Fortunately I got to sit down with Paul Batum from the Azure Mobile Services team and he learned me a thing or two.

I already knew the backend of Azure Mobile Services was node.js. What I didn’t realize is that we can pass in a javascript function to be executed server side for a highly custom search the way that we can with Linq from C#. The syntax is a little weird but it works a treat.

itemTable.where(function (startDate, endDate) {
            return this.Date >= endDate && this.Date <= startDate;
        }, startDate, endDate)
    .read()
    .done(function (results) {
        for (var i = 0; i < results.length; i++) {
           //do something interesting
        };

Notice that inside the where function, I’m passing in another function. This function gets passed back and operates server side. The slightly wonky part is that the function has to accept the parameters that you pass in as well as you have to pass the variables that will be passed to this function. So reading that sample carefully, see that we’re passing three variables to the server side including the function and then the two actual variables that we want to pass to the function that executes on the server.

This allows for some awesome flexibility, well beyond custom date searches. 🙂