Bulletproof fluent interfaces

I attended a Fluent Interface webinar by the inimitable Scott Lilly (see http://scottlilly.com/FIWebinar). Below is my exercise file and some thoughts around what I think are the benefits of a fluent interface.

A fluent interface gives you more control over the way your methods are called. Scott explains it as a three step process, first instantiate, then chain your methods, and finally execute (ICE). And I will present an example of a report in the classic sense, and one built in the fluent way.

download linqpad file: http://share.linqpad.net/w5gdub.linq

Automapper in action

Automapper is an object to object mapper which helps to eliminate yak shaving. It can save you from the tedious task of creating custom code to convert data-store object models to your view model.

I put together a demo because I believe it when I see it in action.

Here's a working LinqPad version here: http://share.linqpad.net/neu8bm.linq

Or see the code online here...

FSharp XML Type provider in action

This is a working sample of an XML type provider. It's a simple scrip. Though Linqpad does crash when dealing with it. Saves a lot of time when writing a quick script to parse an xml document.


Download the linqpad file: http://share.linqpad.net/xlrrfl.linq

A method to get a sitecore item id given a path

This method will give you a sitecore item id back if you give it a fully qualified path as input.

void Main()
{
 var itemId= GetItemId("/sitecore/content").Dump(); 
 
 //get child items
 //Items.Where (i => i.ParentID==itemId).Select (i => new {i.ID, i.Name}).Dump();
 
 //show field information
 Fields.Where (f => f.ItemId==itemId && f.Value!="")
  .Select (f => new 
  {
   FieldName=Items.Where (i => i.ID==f.FieldId).Select (i => i.Name).Single (),
   f.Value,
   f.Language
  })
  .Dump();
  
}



Guid GetItemId(string itemPath)
 {
 
  var pathParts = itemPath.Split(new char[] { '/'}, StringSplitOptions.RemoveEmptyEntries ); 
  var parentId = Guid.Empty;
  var id = Guid.Empty;
  foreach (var part in pathParts)
  {
   if (parentId == Guid.Empty && part.Equals("sitecore", StringComparison.OrdinalIgnoreCase))
   {
     parentId = new Guid("{11111111-1111-1111-1111-111111111111}");
  id = parentId;
    }
   else
   {
    id = GetChildGuid(part, parentId);
 
    if (id != Guid.Empty)
     parentId = id;
    else
    {
     String.Format("Could not find {0}", part).Dump();
     break;
    }
   }
  }
  return id;
}
 
Guid GetChildGuid (string childName, Guid parent_guid)
{
  return Items.Where(i => i.ParentID == parent_guid && i.Name == childName)
   .Select(i => i.ID)
   .FirstOrDefault();
}

How to flatten a list of lists into a flat list in one line of code: SelectMany is your friend

Given that you have a list of lists, how do you flatten it?

how do you flatten it?

With the SelectMany LINQ method, it's easy peasy:

var listOfLists = new List<IEnumerable<int>>() { Enumerable.Range(1, 3), Enumerable.Range(20, 3) };
listOfLists.Dump("List of lists");
listOfLists.SelectMany(lol => lol).Dump("Flat list");

Download linqpad sample, here

Assigning lambda expression to a variable

In the spirit of writing terse code, I was pleasantly surprised that you can assign a lambda expression to a local variable. A quick sample:

void Main()
{
 Func<string, string> sayHello = ((input) => { return input + "!!"; });
 System.Diagnostics.Debug.WriteLine(sayHello("hello world"));
}

Results:

hello world!!

in Func<string, string>, the first string specifies the input parameter's data type, while the last string is for the return type. If you have more than one input parameter, you'd have multiple parameters specified like this <string, string, string, string> and the last one is always for the return type of the function.

My FSharp patter matching code kata

Given a list of numbers, detect when the values 2,3,4 are present one after the other.

Extension method to dump Highlighted search results in Linqpad

Here's an extension method which lets you output the found results as html.

For example, if you wanted to show the result of a search and replace, given:

 var text = "An apple a day keeps the doctor away\n you can say that any day of the year today or tomorrow.";
 var find = "day";
 var replace = "week";
 
 text.HighlightText(find).Dump("Original text");
 text.Replace(find, replace).HighlightText(replace).Dump("updated text");

The result would be:

Original text
An apple a  day  keeps the doctor away  you can say that any  day  of the year.

updated text
An apple a  week  keeps the doctor away  you can say that any  week  of the year.

See extension method below: