querying.md

layout	title	category
datatype	Querying	uMapper

Shorthand

{% highlight c# %} // By default, all relationships are included in a shorthand query: var fatArtist = uMapper.GetSingle(1063); // fatArtist.Genres.Count == 3

// This can get very expensive very fast. You can exclude all relationships // by specifying the optional parameter: var skinnyArtist = uMapper.GetSingle(1063, false); // skinnyArtist.Genres == null

// If performance matters to you, I would advise against using shorthand.

{% endhighlight %}

Longhand

Calling the uMapper.Query<TDestination>() methods gets you a fluent interface to 'query' nodes. I say 'query' because it doesn't implement IQueryable (probably never will). Enumerating the query gives you back all nodes which can be mapped to TDestination (which means models which inherit from TDestination will be included). If you hunger for more query methods, you can write your own extension methods for INodeQuery<TDestination>. {% highlight c# %} // Maps the current node var a = uMapper.Query().Current();

// Maps a node by ID (returns null if it doesn't exist) var b = uMapper.Query().Find(1234);

// Maps many nodes var c = uMapper.Query().Many(new[] { 1111, 2222, 3333 });

// Maps all nodes which can be mapped to 'Artist' var d = uMapper.Query().ToList();

// Maps all nodes which were explicitly mapped to 'Artist' var e = uMapper.Query() .Explicit() .ToList();

// Maps all artist names var f = uMapper.Query() .SelectProperty(artist => artist.Name) .ToList();

// Map all artists with short names var g = uMapper.Query() .WhereProperty( artist => artist.Name, name => name.Length < 5 ) .ToList();

{% endhighlight %}

Querying with paths

{% highlight c# %} var homepage = uMapper.Query() .Include(x => x.Genres) // Single level path .Include(x => x.Artists.Select(y => y.Genres)) // Syntax for multi-level paths .Current(); // Maps the current node

homepage.Genres // populated
homepage.FeaturedArtist // null, as it was not included
homepage.Artists // populated
homepage.Artists.First().Genres // populated

// You can also use string paths (as deep as you like): var otherHomepage = uMapper.Query() .Include("Artists.Genres") .Current(); {% endhighlight %}