With this post I’m back to my lovely OneNote screen clippings, my last few postings were done on Windows8 and I’d no OneNote installed.
So you want to Deserialize Json in .NET! (C#)
How do you go about it?
There are a few approaches, many poeple are familiar with JSon.NET and using it like this
or
Some people may have done it the hard way
But if you add assembly System.Net.Http.Formatting.dll you’ll get a nice little extension ReadAsAsync<T>
http://msdn.microsoft.com/en-us/library/hh836073(v=vs.108).aspx
Enjoy!
What’s wrong with this?
1: public class UsersController : RavenController
2: {
3: public User Get(int userId)
4: {
5: this.AutoSave = false;
6: var user = RavenSession.Load<User>(userId);
7: if (user == null)
8: throw new HttpResponseException("Unable to find user for it " + userId);
9: return user;
10: }
11:
12: // GET /api/values
13: public IQueryable<User> GetAll()
14: {
15: this.AutoSave = false;
16: return RavenSession.Query<User>();
17: }
18: }
The problem is the variable name used for getting a single user the function would never be called.
E.g. if we put http://localhost:65487/api/users/1 into our browser what will happen is the GetAll gets called!
What we need to call is
1: public class UsersController : RavenController
2: {
3: public User Get(int id)
4: {
5: this.AutoSave = false;
6: var user = RavenSession.Load<User>(id);
7: if (user == null)
8: throw new HttpResponseException("Unable to find user for it " + id);
9: return user;
10: }
11:
12: // GET /api/values
13: public IQueryable<User> GetAll()
14: {
15: this.AutoSave = false;
16: return RavenSession.Query<User>();
17: }
18: }
Now you see that the Get takes a variable name of “id” this is key to getting this work.
Note: I’m using IQuerable as this allows me to add some query parameters to my request, e.g.
$filter
A Boolean expression for whether a particular entry should be included in the feed, e.g. Categories?$filter=CategoryName eq 'Produce'. The Query Expression section describes OData expressions.
$orderby
One or more comma-separated expressions with an optional “asc” (the default) or “desc” depending on the order you’d like the values sorted, e.g. Categories?$orderby=CategoryName desc.
$select
Limit the properties on each entry to just those requested, e.g. Categories?$select=CategoryName,Description.
$skip
How many entries you’d like to skip, e.g. Categories?$skip=4.
$top-
Return entries from the top of the feed, e.g. Categories?$top=4
See MSDN for more options.
-- Updated Post --
Thanks to James Hancock for pointing this one out for me. This post is a little misleading in that the $select is currently not supported. Please see http://forums.asp.net/t/1771116.aspx/1?OData%20Support for more information on this. The other query string parameters listed above are supported.
I’m starting this post with a disclaimer. I’m not a RavenDb expect, actually far from it, in fact I’ve only started working with it this evening!
I’m working on a pet project and getting the initial building blocks in place. I read about RavenDB in a recent edition of CODE magazine. The same magazine dealt with some other NoSql databases, e.g. Mongo Db, I’ve had a passing interest in NoSql in the last while so I wanted to get me a piece of the pie, and RavenDB jumped out at me for a few reasons.
- Written in .NET
- Scalability over RDBMS
- RestAPI (although i won’t be using it, my app will have its own REST API using RavenDb managed api underneath)
- .NET API with Linq querying
- Automatic indexing
- Scalability
Create project
Fire up visual studio and create an new MVC4 project
Add the RavenDb package,
Global.asax.cs
Do the very same that is indicated on the Raven website, We need a single Document Store in our application.
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
RegisterGlobalFilters(GlobalFilters.Filters);
RegisterRoutes(RouteTable.Routes);
BundleTable.Bundles.RegisterTemplateBundles();
InitRaven();
}
private void InitRaven()
{
Store = new DocumentStore { ConnectionStringName = "RavenDB" };
Store.Initialize();
IndexCreation.CreateIndexes(Assembly.GetCallingAssembly(), Store);
}
public static DocumentStore Store;
Create RavenController
public abstract class RavenController : ApiController
{
public RavenController()
{
this.AutoSave = true;
RavenSession = TickTockBaby.Mvc.WebApiApplication.Store.OpenSession();
}
public bool AutoSave { get; set; }
public IDocumentSession RavenSession { get; protected set; }
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (RavenSession != null)
{
using (RavenSession)
{
if (this.AutoSave)
RavenSession.SaveChanges();
RavenSession.Dispose();
RavenSession = null;
}
}
}
base.Dispose(disposing);
}
}
Let me explain what I’ve done here…
I’ve initialized the session in the constructor, and cleaned it up in dispose, I also SaveChanges by default unless it gets switched off in a derived class.
Derive from RavenController
public class UsersController : RavenController
{
// GET /api/values
public IEnumerable<string> Get()
{
this.AutoSave = false;
return RavenSession.Query<User>().Select(u => u.Name);
}
}
That’s my initial attempt, hope it helps someone out a little.
I’ll post my final solution possibly using Ninject DI after I’ve used RavenDb for a while and get a better feel for it.
Raven Studio
Check results in browser
I’m working with an XML document all morning, and for the hell of it I decided to open in VS11.
Guess what I found, some pretty cool xml/xsd/xslt support
but the biggest feature I found is the following…
Paste XML as classes! BOOM!!
Loving VS11…
Here is an extension method that I just had to share, TBH I’ve forgotten what I robbed the initial idea from, it wasn’t mine, but it’s something I found that I use over and over.
The problem is I want to use the Distinct() extension method. However the objects I’m creating don’t override the default equality comparer, nor did I want to create a functor and supply to the overload just for this scenario.
Lets have a look of what I’m dealing with.
public class Source
{
public string Code { get; set; }
public string Name { get; set; }
}
Here’s what one would initially try
// Remove any duplicates
c.DependingOnSources = c.DependingOnSources.Distinct();
The problem here is that I don’t use the overload that allows me to specify an equality comparer, and the class itself doesn’t have the default equality comparer.
So what’s the solution?
var set = new HashSet<string>();
c.DependingOnSources = c.DependingOnSources.Where(element => set.Add(element.Name));
It’s a beauty it’s it, and quite simplistic, what I do is create a HashSet of the keys I want o compare, then I use use the Linq Where statement to select all the elements that I can add to the list. If you’re familiar with HashSet you’ll know that for first time we try add an element it will be not exist in the set and it gets added to the set and returns true, because the set.Add returns true.. we satisfy the Func in the Where clause and it gets added to the items that get returned.
Simple ey.. yes true, but it gets better, we can make this a little more generic and leverage an extension method to do the lifting for us.
internal static class LinqExtensions
{
public static IEnumerable<TSource> DistinctBy<TSource, TKey>(
this IEnumerable<TSource> source, Func<TSource, TKey> selector)
{
var set = new HashSet<TKey>();
return source.Where(element => set.Add(selector(element)));
}
}
So now we can call our method like so
// Remove any duplicates
c.DependingOnSources = c.DependingOnSources.DistinctBy(k => k.Name);
Neat ey! (another common method is to use GroupBy and Select.)