Repeat a string N times in C#

Sometimes I want to repeat a given string several times for formatting purposes. The following code can be either made into an extension method with slight changes or a utility method:

string.Join("", Enumerable.Repeat("a", 8).ToArray());

The code above repeat "a" 8 times and returns "aaaaaaaa".

Hating hosts file?

Sometimes I found that it is pretty annoy to keep editing the hosts file to add a new development domain on my local machine and a colleague told me that there are several domains (and their sub-domains) that automatically loop back to 127.0.0.1 (localhost), for example, 42foo.com, localtest.me, lvh.me, etc.

I personally like localtest.me as it seems more logical to me. So now when I am developing a new site, I could use something like newsite.dev.localtest.me directly without adding an entry in hosts file.

Checking null for Sitecore.Data.ID

The Sitecore.Data.ID class exposes a IsNull property which the documentation says it checks whether the instance is null. However I discovered that when the ID variable is actually null it throws Object reference set to null instance of object exception.

So it is better to the following code in this case (perhaps always?):

Sitecore.Data.ID.IsNullOrEmpty(myID)

Linq.js - where to filter on sub collections

Linq.js (you can find more info on CodePlex - http://linqjs.codeplex.com) provides convenient way manipulating your javascript collections (mainly arrays) and exposes it as LINQ that we are familiar with in .NET world.

One issue I found that it is hard to find information on how to achieve it is that when I want to apply the where clause on sub collections.

For example, given the following array:

var cars = [
  {id: "F001", make: "Ford", model: "Fiesta", 
    colors: [
      {id: 1, name: "Red"},
      {id: 2, name: "Blue"}
    ]
  },
  {id: "T001", make: "Toyota", model: "Corolla",
    colors: [
      {id: 1, name: "Red"},
      {id: 3, name: "Silver"}
    ]
  },
  {id: "T002", make: "Toyota", model: "Yaris",
    colors: [
      {id: 1, name: "Red"},
      {id: 3, name: "Silver"},
      {id: 4, name: "White"}
    ]
  }
];

It is pretty easy to find cars that are made by Toyota (note that the code examples below are using linq.js 3.x:

var toyotaCars = Enumerable.from(cars)
                           .where("c=> c.make == 'Toyota'");

And we will get Corolla and Yaris.

However, when I want to find cars that are available in blue and how do I suppose to do that?

People might have tried the following already:

var blueCars = Enumerable.from(cars)
                         .where("c=> c.colors.name == 'Blue'");

Or

    .where(function(c) {return (c.colors.name == 'Blue');})

Unfortunately this is not how it works and you will get nothing. Obviously linq.js is trying to work as close as to .NET LINQ but nothing is perfect. So to achieve what we want is the following:

var blueCars = Enumerable.from(cars)
    .where(function(o) {
      return (Enumerable.from(o.colors)
                        .where("c => c.name == 'Blue'").any());
    });

Here you go, we will get Ford Fiesta!