Scott Hanselman

NerdDinner being updated to MVC3 with Razor, HTML5, GeoLocation, EF CodeFirst, jQuery Mobile, YepNope and Modernizr and a fixed Mobile Device Capabilities ViewEngine

August 26, '11 Comments [28] Posted in ASP.NET | ASP.NET MVC | HTML5 | IE9 | Mobile | NerdDinner
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NerdDinner with jQuery Mobile on an iPhone asking for my locationTwo years ago Rob, Phil, and I released our MVC 1.0 book with the Gu helping with the big intro. I created the basic Nerd Dinner sample application (code here) and released the first 185 pages for free. Since the initial 1.0 release, we've had help from lots of people like Dave Ward, Andrew Aarnott and Jon Galloway on a lot of little things like JavaScript and OpenAuth support, then John V. Petersen moving us to MVC3 with Razor Views, and Peter Mourfield taking on lots of JavaScript and new features. These guys started working on a feature here and a feature there in our spare time. It's been a collaborative effort with folks dropping in, contributing here and there with long periods of silence in between.

After John V. Petersen moved us to MVC3 and Razor, Peter Mourfield got on a feature tear and now we've added or updated:

Now, to be clear, this isn't a release, it's an initial almost release. Call it an Alpha. That said, it's up live at http://www.nerddinner.com and the source continues to move forward in the Trunk on Codeplex. We've got some inconsistencies with the mobile site and back  button, and geoloc is not working completely on an iPhone but it's decent on a browser. We're working on this an hour here and an hour there, but if you, Dear Reader, find any bugs in the trunk or obvious stupid mistakes, please to let us know and *cough* submit a patch *cough*. Or at least leave a nice Issue we can track.

As we get these features working rock solid, Pete and I will do a series of posts digging in to what worked well and what didn't in each feature. Already Pete has a good blog post talking about adding HTML5 Geolocation to Nerd Dinner with yepnope.js, and Modernizr. He used yepnope, a great library for saying "do you support this feature? Yep? Get this JS. Nope? Get this JS. For example:

<script type="text/javascript">
$(document).ready(function () {
yepnope({
test: Modernizr.geolocation,
yep: '@Url.Content("~/Scripts/geo.js")',
nope: '@Url.Content("~/Scripts/geo-polyfill.js")',
callback: function (url, result, key) {
getCurrentLocation();
}
});
});
</script>

Love it. More details and code on Pete's blog post. In the image below you can see IE9 warning me that my local site wants to track my physical location.

Geolocation in IE9

Here's Firefox prompting me for a location on the live site:

Firefox wants to know where I am

And Chrome:

Chrome knows where you live!

As I said, there are surely lots of bugs and subtleties we need to iron out, but I'm glad we're actually moving this sample forward. Hope you enjoy, and do feel free to fix our bugs for us, Dear Reader. ;)

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. I am a failed stand-up comic, a cornrower, and a book author.

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Microsoft "Daily Build" Nerd Dinner - August 4th in Seattle, Redmond

July 30, '10 Comments [9] Posted in ASP.NET | IIS | NerdDinner
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Are you in King County/Seattle/Redmond/Bellevue Washington and surrounding areas? Are you a huge nerd? Perhaps a geek? No? Maybe a dork, dweeb or wonk. Maybe you're in town for an SDR (Software Design Review) or VSLive! Quite possibly you're just a normal person and a member of the general public.

We're holding a Nerd Dinner (it's like dinner, except with nerds) next week on Weds, Aug 4th at Crossroads Bellevue Mall Food Court at 6pm.

This one will be different from usual. Why?

It's a Daily Build Nerd Dinner!

We'll have Program Managers and Developers directly from Microsoft who'll bring their laptops with "Daily Builds" of stuff they are working on. Daily Builds mean literally stuff they've built that day that's cool. You'll give them feedback and they'll show you cool new stuff like the Razor View Engine and Visual Studio Tooling.

If you are a member of the public, be here!

Nerd Dinners are for us. All are welcome. Just come on by. We'll be near the Chess Board in the Food Court. Bring your co-workers and your social media friend!

Please spread the word! RSVP and tweet about this dinner at http://nrddnr.com/2770

Add to your calendar now...here's an iCal link for your Outlook or other calendar.

See you soon!

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. I am a failed stand-up comic, a cornrower, and a book author.

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Extending NerdDinner: Exploring Different Database Options

May 20, '10 Comments [37] Posted in ASP.NET | ASP.NET MVC | Data | NerdDinner | Open Source | Source Code
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The original NerdDinner Sample was very simple. Two samples, simple, in fact. Perhaps it's the new Northwind, as it's a good way to start working with ASP.NET MVC. However, it's not a perfect sample or an idealized example on how to do many things that users want to do.

Fortunately, there's been lots of cool folks in the community who have "forked" NerdDinner and done interesting stuff with it. Each of these samples is usually focused on a specific scenario, so they won't necessarily be merged with the trunk, but they are educational nonetheless.

Four Five NerdDinners - Each Accessing Data Differently

When NerdDinner was originally done, I did it in Linq To SQL as L2S was fast, easy, had a 1:1 relationship between objects and tables, and frankly, I wasn't really feeling Entity Framework 3.5. Fast forward to .NET 4 and the Entity Framework 4 is pretty nice. The current NerdDinner v2 sample (available in the Trunk on the NerdDinner Codeplex Site, click Source Control) uses Entity Framework 4.

I heard, however, that Chris Sells was interested in exploring a ASP.NET MVC sample that accessed databases via the various ways you'll find in the wild:

  • ADO.NET Connected (DataReaders)
  • ADO.NET Disconnected (DataSets)
  • LINQ to SQL
  • LINQ to Entities (Entity Framework)

Chris worked with Nick Muhonen from Useable Concepts and Nick created four samples. Nick has posted a very in-depth article on http://msdn.com/data.

These samples are on VS2010 and ASP.NET MVC 2. Let's compare and contrast. I've also included a sample that Ayende built for to teach me NHibernate last year as the fifth sample. Big thanks to Ayende for all he does for the community, giving of his time, and for keeping Microsoft honest(ish).

ADO.NET Connected (DataReaders)

Scandalous! People still use these? Of course they do. The are wicked fast and many generated DALs (data access layers) have a DataReader at their heart.

Here's the slightly modified IDinnerRepository that was used in this first sample. Note it's not using IQueryable. I understand that it would be ideal to have a single IDinnerRepository interface and have all these samples share it, but these database access techniques differed so greatly that I'm told they gave up as it made the rest of the code smell (more) just to meet that one goal.

public interface IDinnerRepository {

//Data Access Methods

IEnumerable<Dinner> FindAllDinners();
IEnumerable<Dinner> FindByLocation(float latitude, float longitude);
IEnumerable<Dinner> FindUpcomingDinners();
Dinner GetDinner(int id);

void AddDinner(Dinner dinner);
void UpdateDinner(Dinner dinner);
void DeleteDinner(int id);

void AddDinnerRsvp(int dinnerID, RSVP rsvp);
}

You've likely seen code like this before. At least it's not concatenating the SQL manually! It could also be a sproc. The pattern remains.

public IEnumerable<Dinner> FindByLocation(float latitude, float longitude)
{
using (var connection = new SqlConnection(this.connectionString))
{
var commandText =
@"
select d.DinnerID, d.Title, d.EventDate, d.[Description], d.HostedBy,
d.ContactPhone, d.[Address], d.Country, d.Latitude, d.Longitude
from Dinners d
inner join dbo.NearestDinners(@Latitude,@Longitude) nd on
d.DinnerID = nd.DinnerID
where @CurrentDate <= d.EventDate
order by d.DinnerID

select r.RsvpID, r.DinnerID, r.AttendeeName from RSVP r
inner join Dinners d on
d.DinnerID = r.DinnerID
inner join dbo.NearestDinners(@Latitude,@Longitude) nd on
d.DinnerID = nd.DinnerID
where @CurrentDate <= d.EventDate
order by r.DinnerID, r.RsvpID
";
var command = new SqlCommand(commandText, connection);
var parameters = new[]{
new SqlParameter{ParameterName = "Latitude", DbType = DbType.Double, Value = latitude},
new SqlParameter{ParameterName = "Longitude", DbType = DbType.Double, Value = longitude},
new SqlParameter{ParameterName = "CurrentDate", DbType = DbType.Date, Value = DateTime.Now}};

command.Parameters.AddRange(parameters);

connection.Open();
return GetDinners(command);
}
}

Here's a snippet of the private method, GetDinners, that does the tearing apart of the DataReader and turning it into object(s):

private List<Dinner> GetDinners(SqlCommand command)
{
var returnDinners = new List<Dinner>();
using (var reader = command.ExecuteReader())
{
//Project first result set into a collection of Dinner Objects

while (reader.Read())
{
var dinner = new Dinner()
{
DinnerID = (int)reader["DinnerID"],
Title = (string)reader["Title"],
Description = (string)reader["Description"],
Address = (string)reader["Address"],
ContactPhone = (string)reader["ContactPhone"],
Country = (string)reader["Country"],
HostedBy = (string)reader["HostedBy"],
EventDate = (DateTime)reader["EventDate"],
Latitude = (double)reader["Latitude"],
Longitude = (double)reader["Longitude"]
};
returnDinners.Add(dinner);
}
//...

Pretty classic stuff. I generated TONS of for many years using tools like CodeSmith and T4. Generated code is best not seen. Plus, if you write this by hand, a lot can go around and it's almost always because of copy-paste errors. The compiler can't save you if half your code is written in another language tunneled inside a string.

ADO.NET Disconnected (DataSets)

I once called DataSets the spawn of Satan and destroy of all that is holy. I stand by that. ;) They have a way of leaking all over the place, as exemplified by this IDinnerRepository interface. Look away!

public interface IDinnerRepository {

//Data Access Methods
IEnumerable<NerdDinnerDataSet.DinnerRow> FindAllDinners();
IEnumerable<NerdDinnerDataSet.DinnerRow> FindByLocation(float latitude, float longitude);
IEnumerable<NerdDinnerDataSet.DinnerRow> FindUpcomingDinners();
NerdDinnerDataSet.DinnerRow GetDinner(int id);
void AddDinner(NerdDinnerDataSet.DinnerRow dinner);
void DeleteDinner(NerdDinnerDataSet.DinnerRow dinner);

void AddDinnerRsvp(NerdDinnerDataSet.DinnerRow dinner, NerdDinnerDataSet.RSVPRow rsvp);
void DeleteRsvp(NerdDinnerDataSet.RSVPRow rsvp);

// Persistence Method
void Save();
//Object factory methods

NerdDinnerDataSet.DinnerRow CreateDinnerObject();
NerdDinnerDataSet.RSVPRow CreateRsvpObject();
}

With apologies to the original creator of the Regular Expression joke, I will co-opt it for this new one:

So you've got a problem, and you've decided ADO.NET DataSets to solve it. So, you've got two problems... - Me

What does FindByLocation look like now?

public IEnumerable<NerdDinnerDataSet.DinnerRow> FindByLocation(float latitude, float longitude)
{
var now = DateTime.Now;
var dinnerTableAdapter = new DinnerTableAdapter();
var rsvpTableAdapter = new RSVPTableAdapter();

dinnerTableAdapter.FillByLocation(nerdDinnerDataSet.Dinner, latitude, longitude, now);
rsvpTableAdapter.FillByLocation(nerdDinnerDataSet.RSVP, latitude, longitude, now);
return this.nerdDinnerDataSet.Dinner;
}

The TableAdapters were created as part of the DataSetDesigner. Here' a screenshot from VS2010:

DataSet Designer

The Adapters fill the DataTables that consist of Rows. This unfortunately leaks out of our Repository into our Controller as our "Model" is now a DinnerRow. That then leaks (inappropriately) into a ViewPage of type...wait for it...System.Web.Mvc.ViewPage<NerdDinner.Models.NerdDinnerDataSet.DinnerRow>.

If you're going to use DataSets or Rows or DataTables, it's just that much more important that you use a good ViewModel projection. I personally go out of my way to not use DataSets and bump into them only in legacy code. Try to avoid them - I'd prefer the DataReader example over this one.

LINQ to SQL

Remember that LINQ to SQL is a one to one mapping between the physical tables and columns of the database and the objects it creates. Many folks prefer to use it as a DAL (Data Access Layer) that just happens to make objects, then pull the data out of the auto-generated objects into smarter business objects, such that the developer downstream never sees the generated L2S objects. Others just use them all through. For simple samples, I used to use LINQ to SQL straight, and I still do for small (< 5 page) projects, but lately I've been using EF4 as it's just as easy. Anyway, here's the now more sensible modified interface:

public interface IDinnerRepository {
IQueryable<Dinner> FindAllDinners();
IQueryable<Dinner> FindByLocation(float latitude, float longitude);
IQueryable<Dinner> FindUpcomingDinners();
Dinner GetDinner(int id);

void Add(Dinner dinner);
void Delete(Dinner dinner);

void Save();
}

And then the FindByLocation implementation:

public IQueryable<Dinner> FindByLocation(float latitude, float longitude) {
var dinners = from dinner in FindUpcomingDinners()
join i in db.NearestDinners(latitude, longitude)
on dinner.DinnerID equals i.DinnerID
select dinner;

return dinners;
}

image Notice the "NearestDinners" method there. That's a clever thing, I think. The database has a scalar-valued function called DistanceBetween for calculating the distance between two lat-longs (thanks Rob Conery!) and a table value function called NearestDinners. They look like functions from LINQ to SQL's point of view and can be included in a LINQ to SQL query as seen above.

image 

Nice and clean.

LINQ to Entities (Entity Framework)

Entity Framework 4 uses the same interface as above and the same FindByLocation:

public IQueryable<Dinner> FindByLocation(float latitude, float longitude) {
var dinners = from dinner in FindUpcomingDinners()
join i in NearestDinners(latitude, longitude)
on dinner.DinnerID equals i.DinnerID
select dinner;

return dinners;
}

The one small difference, you may notice, is that NearestDinners isn't hanging off the "db" object (the DataContext) as it was with LINQ to SQL. Instead, in order to maintain the same clean query structure, those are helper methods. One is an EdmFunction whose signature maps to that scalar function, and NearestDinner is implemented in code directly.

[EdmFunction("NerdDinnerModel.Store", "DistanceBetween")]
public static double DistanceBetween(double lat1, double long1, double lat2, double long2)
{
throw new NotImplementedException("Only call through LINQ expression");
}

public IQueryable<Dinner> NearestDinners(double latitude, double longitude)
{
return from d in db.Dinners
where DistanceBetween(latitude, longitude, d.Latitude, d.Longitude) < 100
select d;
}

Don't worry about that NotImplementedException, when the method is used in a LINQ to Entities Expression it's automatically mapped to the DistanceBetween function in the database as in the attribute.

I'd like to see better support for TVFs in EF, and I need to dig in to see if there's a better way that outlined here. Entity Framework also supports multiple databases, so you can get an Oracle Provider or a MySQL provider, etc.

So there you have four different database implementations for NerdDinner. Last, but not least, is a sample that Ayende wrote for me to teach me NHibernate, and I would be remiss to not include it in such a comparison.

NHibernate

This sample was written least year with ASP.NET MVC 2 on VS2008 using NHibernate 2.1. I'd love to see an updated version using even newer techniques.

Hibernate has the concept of a "Session" that lives for the life of a request in a Web Application. There's a config file (or a fluent configuration) that has all the properties and connection strings, (similar to EDMX files in EF or DBMLs in L2S) and this all gets setup in the Global.asax. The session is created in the BeginRequest and disposed in the EndRequest.

public MvcApplication()
{
BeginRequest += (sender, args) => CurrentSession = SessionFactory.OpenSession();
EndRequest += (sender, args) => CurrentSession.Dispose();
}

Here's the FindByLocation method. This example isn't 100% fair as this version of NHibernate doesn't support those custom functions I've been talking about. I'm going to see if the latest does and update this post. However, this does give you insight into its flexibility as it allowed inline SQL, set two parameters and returned a list of ints in a very tight single line of code.

public IQueryable<Dinner> FindByLocation(float latitude, float longitude)
{
// note that this isn't as nice as it can be, since linq for nhibernate
// doesn't support custom SQL functions right now

var matching = session.CreateSQLQuery("select DinnerID from dbo.NearestDinners(:latitude, :longitude)")
.SetParameter("longitude", longitude)
.SetParameter("latitude", latitude)
.List<int>();

return from dinner in FindUpcomingDinners()
where matching.Any(x => x == dinner.DinnerID)
select dinner;

}

A better example that lets NHibernate shine would be something more typical like:

public IQueryable<Dinner> FindUpcomingDinners()
{
return from dinner in FindAllDinners()
where dinner.EventDate >= DateTime.Now
orderby dinner.EventDate
select dinner;
}

You'll note that LINQ to NHibernate is nice and comfortable and looks just like you'd expect it to.

Just like EF and LINQ to SQL, there's a mapping file that explains how tables and columns and dataTypes map to real objects, although there isn't a visual editor as far as know. I believe there are fluent ways to express this in code, so if you're an NHibernate user, let me know alternative ways to express this and I'll update the post.

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NerdDinner" namespace="NerdDinner.Models">
<class name="Dinner" table="Dinners" lazy="false">
<id name="DinnerID">
<generator class="identity"/>
</id>
<property name="Title"/>
<property name="EventDate"/>
<property name="Description"/>
<property name="HostedBy"/>
<property name="ContactPhone"/>
<property name="Address"/>
<property name="Country"/>
<property name="Latitude"/>
<property name="Longitude"/>
<bag name="RSVPs" cascade="all-delete-orphan" inverse="true">
<key column="DinnerID"/>
<one-to-many class="RSVP"/>
</bag>

</class>
<class name="RSVP" table="RSVP" lazy="false">
<id name="RsvpID">
<generator class="identity"/>
</id>
<property name="AttendeeName"/>
<many-to-one name="Dinner"
column="DinnerID"/>
</class>
</hibernate-mapping>

This mapping file is actually marked as an Embedded Resource, and is accessed at runtime by the NHibernate runtime. You just need to make it, and the magic happens for you. NHibernate's claim to fame is support for lots of different databases like SQL Server, Oracle, MySQL and more. There's also lots of supporting projects and libraries that orbit NHibernate to give you additional control, or different ways to express your intent.

Conclusion

There's lots of choices for Database Access on .NET. You'll run into DataReaders in older or highly tuned code, but there's no reason it can't be hidden in a Repository and still be pleasant to use. LINQ to SQL is nice, lightweight and fast and has dozens of bug fixes in .NET 4, but Entity Framework is the way they are heading going forward. Plus, Entity Framework 4 is *way* better than EF 3.5, so I'm using it for any "larger than small" projects I'm doing and I'm not having much trouble. NHibernate is very mature, actively developed and has a great community around it and it's not going anywhere.

In my opinion, if you're doing database access with .NET you should be using Entity Framework 4 or NHibernate.

Four Database-styles Sample

nddatafoursamples

NHibernate Sample

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. I am a failed stand-up comic, a cornrower, and a book author.

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Extending NerdDinner: Adding MEF and plugins to ASP.NET MVC

May 20, '10 Comments [16] Posted in ASP.NET | ASP.NET MVC | NerdDinner | Open Source | Source Code
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The original NerdDinner Sample was very simple. Two samples, simple, in fact. Perhaps it's the new Northwind, as it's a good way to start working with ASP.NET MVC. However, it's not a perfect sample or an idealized example on how to do many things that users want to do.

Fortunately, there's been lots of cool folks in the community who have "forked" NerdDinner and done interesting stuff with it. Each of these samples is usually focused on a specific scenario, so they won't necessarily be merged with the trunk, but they are educational nonetheless.

Jon Galloway and I have also added a few things to NerdDinner, taking it in a more social direction, as Jon's MVC Music Store today is a better "getting started" sample for ASP.NET MVC 2. We'll be doing a series of posts on the interesting things the community has added to NerdDinner as well as some of the ones Jon and I added and presented at Mix a few months back. Soon Jon and I will release an updated NerdDinner v2 on CodePlex (although it's been in the source code tab for weeks) with lots of fixes, new features. We'll also add many of these "one off" samples as well and host them on CodePlex.

I spoke to Microsoft Engineer Hamilton Verissimo de Oliveira, aka "Hammett" (you likely know him from the Castle Project and Monorail) about making a NerdDinner sample that included MEF (Managed Extensibility Framework) since much of MEF is built into .NET 4 now. He was kind enough to do it, but I'm just blogging it now, so thanks to Hammett for his kindness and patience.

NerdDinner on MEF

MEF lives in System.ComponentModel.Composition. Hammett's done a number of interesting things it his sample, adding Microsoft.ComponentModel.Composition.Extensions and Microsoft.ComponentModel.Composition.Extensions.Web namespaces building in some nice extension methods for common techniques as well as and implementation of IControllerFactory and a derivation of HttpApplication.

MefControllerFactory

Remember MEF is about making applications easily composable. In this sample Hammett has created his own MefControllerFactory, replacing the default controller factory that comes with ASP.NET MVC. ASP.NET MVC makes it easy to change:

protected override void Application_Start()
{
base.Application_Start();

ControllerBuilder.Current.SetControllerFactory(new MefControllerFactory(base.ScopeManager));

RegisterRoutes(RouteTable.Routes);

ViewEngines.Engines.Clear();
ViewEngines.Engines.Add(new MobileCapableWebFormViewEngine());
}

Notice his controller factory has a ScopeManager. This is a web application, and some components might be at Application Scope (create them once and hang on) and some might be at Request scope (make a new one each request).

For controllers, he's effectively recreated the default behavior of the ASP.NET MVC's controller factory, but in doing it, has given us lots of ways we can jump in an change the behavior in exotic ways by overriding CreateRootCatalog in MefhttpApplication. It's default implementation looks in /bin:

protected virtual ComposablePartCatalog CreateRootCatalog()
{
return new DirectoryCatalog(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "bin"));
}

As you probably know, ASP.NET MVC looks for classes via a convention. It looks for classes with the word "Controller" at the end that are also IController implmentations. Here's the MEF way to declare that convention using Microsoft.ComponentModel.Composition.Extensions. Note the use of scope.

[assembly: Discovery(typeof(Conventions))]

namespace NerdDinner
{
public class Conventions : ConventionDiscovery
{
public Conventions()
{
Add(PartRegistration.
Types(t => t.Name.EndsWith("Controller") && !t.IsAbstract).
Exporting((c, t) => c.
Contract(typeof (IController)).
Metadata("Name", t.Name.Substring(0, t.Name.Length - "controller".Length)).
Metadata("Mode", WebScopeMode.Request))
);
}
}
}

Pretty cool.

Controllers and their Needs

Whenever a more advanced programmer looks as the NerdDinner code they usually say they they really don't like this:

public DinnersController() : this(new DinnerRepository()) 
{
}

public DinnersController(IDinnerRepository repository)
{
dinnerRepository = repository;
}

The second constructor takes an IDinnerRepository, allowing us to make different implementations, but the default constructor says, "well, here's a concrete implementation if you don't give one." It's a slippery slope and by adding the default implementation I get to sidestep using dependency injection while making the controller testable, but I've tied my controller down with a direct dependency to the DinnerRepository. This is sometimes called "Poor Man's IoC" and many would say that this is a very poor man. That's a religious argument, but Hammett takes a stand by removing the default constructor.

public class DinnersController : Controller
{
private IDinnerRepository dinnerRepository;

public DinnersController(IDinnerRepository repository)
{
dinnerRepository = repository;
}
//...
}

So how does a DinnersController ever get an IDinnerRepository? The idea is that it's not the controllers job to worry about the how, it's only its job to want.

MEF is effectively a Dating Service for Components. Here DinnerRepository is saying it's available and it wants to meet someone who is also into "IDinnerRepository."

[Export(typeof(IDinnerRepository))]
public class DinnerRepository : NerdDinner.Models.IDinnerRepository {

That [Export] attribute is its way to saying, "I'm on the market. Matchmaker, make a match!" When MEF is asked for a Controller and it notices that it has no default constructor, as in our case, it looks at the available constructors and says, "Oh, DinnersController wants to meet someone too! I I think I know just your type." Then it creates a DinnerRepository and calls the DinnersController constructor passing it in. It injects the dependency.

Often you'll see the other components advertising their interest with an [Import] attribute, but that's not necessary in this example because all the Controllers were created via the MefControllerFactory. They don't need attributes, as they've already walked in the door of our dating service!

Other Services MEFified

Recently in a review of MVC Music Store Ayende (and others before him, as well) dissed on these line of code, which actually come with ASP.NET MVC 2 out of the box and weren't written for the sample. (Although they weren't changed)  Phil can speak to specific decisions as I wasn't involved, but many folks who are into dependency injection don't like this. This is effectively the same maneuver as shown above, written slightly differently.

public class AccountController : Controller 
{
public AccountController()
: this(null, null) {
}

public AccountController(IFormsAuthentication formsAuth, IMembershipService service)
{
FormsAuth = formsAuth ?? new FormsAuthenticationService();
MembershipService = service ?? new AccountMembershipService();
}
//...
}

Hammett's implementation just uses MEF, so:

public AccountController(IFormsAuthentication formsAuth, IMembershipService service)
{
FormsAuth = formsAuth;
MembershipService = service;
}

Again, the whole point is that the dependencies get figured out automatically, each one wearing the "I'm available for hooks ups" attributes of [Export(typeof(IFormsAuthentication))] and [Export(typeof(IMembershipService))] respectively.

All in all, MEF is a nice clean addition to an ASP.NET MVC app. Thanks to Hammett for his hard work!

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. I am a failed stand-up comic, a cornrower, and a book author.

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July 7th - Seattle/Redmond/Bellevue Nerd Dinner

July 6, '09 Comments [1] Posted in NerdDinner
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blogging

Are you in King County/Seattle/Redmond/Bellevue and surrounding areas? Are you a huge nerd? Perhaps a geek? No? Maybe a, dork, dweeb or wonk. Maybe you're in town for an SDR (Software Design Review) or just hanging out. Quite possibly you're just a normal person.

Regardless, why not join us for some Mall Food at the Crossroads Bellevue Mall Food Court on July 7th around 6:00pm?

All the details are at http://www.nerddinner.com/717

Also, please Tweet This!

If you want to come and share something with the group, please do! We're language and technology agnostic and always eager to learn about new stuff.

It'd be great if Microsoft Employees came also - everyone loves to put a face to a blog and sometimes Microsoft folks get tunnel vision and don't learn about what's going on in other groups! All are welcome...Please spread the word!

Hope to see you there. If not, I shall eat my Spicy Chicken alone in peace.

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. I am a failed stand-up comic, a cornrower, and a book author.

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