http://www.<domain>.de/Post/145732 – URL with a meaningless Id
http://www.<domain>.de/Post/Creating-slugs-with-Action-filters – speaking URL with a slug

Even for humans speaking URLs are much better instead of meaningless URLs with Ids. You can already see what will occur when opening a link.

Basic slug implementation

We start with the creation of a new Route. This can be done by adding the following route to the Global.asax:

routes.MapRoute(
    null,
    "Post/{slug}",
    new { controller = "Post", action = "Show", slug = string.Empty });

With this route we are able to create URLs like shown in the sample above. As you can see inside the route, we need a post controller with an action called show. The following code shows a sample implementation of this controller (I assume you have a working DI-Configuration and the BlogPostRepository is injected)

private readonly IBlogPostRepository blogPostRepository;

public PostController(IBlogPostRepository blogPostRepository)
{
    this.blogPostRepository = blogPostRepository;
}

public ActionResult Show(string slug)
{
    if (slug.Equals(string.Empty))
    {
        return this.HttpNotFound();
    }

    var blogPost = blogPostRepository.FindPost(slug);
    if (blogPost == null) {
        return this.HttpNotFound();
    }

    return View(blogPost);
}

Inside the action show, we check that a slug value is provided thru the URL. If no slug value is present we return HttpNotFound (404) as result. Having a slug value inside the URL we can call the repository which is responsible for fetching data from the data store. If the URL is valid, a BlogEntry is fetched from the repository. The result should be given to the view to display the data. For the reason the repository returns no result we return another 404.
The problem with this implementation is that the size of the controller can increase very fast, especially when you have more parameters.

Slugs with Action Filters

Now I want to show you the same implementation using action filters. In my opinion this is quiet handy and better then the basic implementation.
We start with the implementation of the new action filter.

public class BlogPostFilterAttribute : ActionFilterAttribute {

    [Dependency]
    public IBlogPostRepository BlogPostRepository { get; set; }

    public override void OnActionExecuting(ActionExecutingContext 
        filterContext) {
        var slug = filterContext.RouteData.Values["slug"] as string;

        if (slug.Equals(string.Empty)) {
            filterContext.Result = new HttpNotFoundResult();
            return;
        }

        var blogPost = BlogPostRepository.FindPost(slug.ToString());

        if (blogPost == null) {
            filterContext.Result = new HttpNotFoundResult();
            return;
        }

        filterContext.ActionParameters["BlogPost"] = blogPost;
    }
}

As you can see, the code looks similar to the basic implementation. What changed is the fact that we extract the slug value from the RouteData of the filterContext. For the cases we want to display a 404 we provide the filterContext result with a new instance of HttpNotFoundResult. On the happy path when we found a post with the help of the repository, the blogPost entry is stored as action parameter on the filterContext. Now we need to update the show action. First we need to provide the new attribute on the action. Next we need to change the method parameters from string to blogPost. The blogPost parameter inside the action will now be filled with the blogPost data which was fetched inside the action filter. Last but not least we can remove all the unnecessary code from the action. The show action should look similar to the following code:

[BlogPostFilter]
public ActionResult Show(BlogPost blogPost) {
    return View(blogPost);
}

Add support for Property Injection on Action Filters

The special thing about action filters is that we need to write some additional code to support injecting data into action filters. In the code above you can already see that I provided the Dependency attribute on the BlogPostRepository property. Without the customizing the property injection didn’t work. What we need to do, I found inside a blog post from Brad Wilson (http://bradwilson.typepad.com/blog/2010/07/service-location-pt4-filters.html).
We need write a filter attribute provider, which is provided with your dependency injection container. The following code shows a sample implementation for unity.

public class UnityFilterAttributeFilterProvider : 
    FilterAttributeFilterProvider {
    private readonly IUnityContainer container;

    public UnityFilterAttributeFilterProvider(IUnityContainer container) {
        this.container = container;
    }

    protected override IEnumerableGetControllerAttributes(
        ControllerContext controllerContext,
        ActionDescriptor actionDescriptor) {

        var attributes = base.GetControllerAttributes(controllerContext, 
            actionDescriptor);

        foreach (var attribute in attributes) {
            this.container.BuildUp(attribute.GetType(), attribute);
        }

        return attributes;
    }

    protected override IEnumerableGetActionAttributes(
        ControllerContext controllerContext,
        ActionDescriptor actionDescriptor) {

        var attributes = base.GetControllerAttributes(controllerContext, 
            actionDescriptor);

        foreach (var attribute in attributes) {
            this.container.BuildUp(attribute.GetType(), attribute);
        }

        return attributes;
    }
}

Inside the Global.asax you need to add the following code inside the Application_Start. This removes the default filter and adds the filter with the DI container to the FilterProviders.

var filterAttributProvider = FilterProviders.Providers.Single(f => f is FilterAttributeFilterProvider);
FilterProviders.Providers.Remove(filterAttributProvider);

var provider = new UnityFilterAttributeFilterProvider(container);
FilterProviders.Providers.Add(provider);

After this last step you should be able to use the injected repository.

Conclusion

With the help of action filters, it’s easier to reduce the controller size and make the code reusable thru an attribute which can be provided on different controllers and actions.

In the last weeks I went to two different areas for a short skiing day. One day I went directly after work to Oberaudorf. The open a couple of days per week for floodlight skiing. The conditions where really good and I really enjoyed the time there expect the temperatures. It was freezing cold at the last lift rides.

Today I spent the day at Brauneck. This ski area is only 60 km away from Munich. It was a beautiful day. The weather was cold (about -18 degrees when I arrived) and sunny. The ski run is nice with some challenging sections.

Have a look at the photos I have taken at both places (only handy pictures, sorry!).

Skiing at Germany VIEW SLIDE SHOW DOWNLOAD ALL

Cheers,

Daniel

Okay watch people doing their work sounds not that great. But we were able to watch some guys, who work for a company, which is responsible for the transportation of heavy loads with helicopters.

What they did was pretty cool. Their job was to fly a Bentley to the top of the neighbour building. Therefore I had a great view and was able to watch the whole action and took a small video which you can watch here if you like.

Cheers,

Daniel

Mongoexport offers an ability to export data to csv which you can easily read with Excel. This allows “normal” users to display, sort & filter data in their familiar environment. Especially for flat documents the csv export is a great option.

To export data from a collection you can use a command which is similar to this one:

mongoexport -d <databaseName> -c <collectionName> -f “<field1,field2>” --csv -o <outputFile>

But wait there is one thing which I don’t like about this. We must define the fields we want to export. When you use the “csv”-option for mongoexport, the field-options becomes required. But what can I do to avoid a hard coded list of fields? Especially on an environment where many changes will happen, you need a solution which works without a manual edited field list.

What we can do is a map/reduce to get all field names from every document inside a collection. With this result you are able to call mongoexport with a field list which is generated on the fly. Details about map/reduce for MongoDB can be found at the following address: http://www.mongodb.org/display/DOCS/MapReduce

The map/reduce can look like the following example:

function GetAllFields() {
    map = function(){
        for (var key in this) { emit(1, key); }
    };

    reduce = function(key, values) {
        var resultArray = [],
            removeDuplicates = function (elements) {
                var result=[],
                    listOfElemets={};
                for (var i=0,elemCount=elements.length; i < elemCount; i++) {
                    listOfElemets[elements[i]]=true;
                }
	        for (var element in listOfElemets) {
                    result.push(element);
                }
            return result;
        }

        values.forEach(function(value) {
            resultArray.push(value);
        });
        return removeDuplicates(resultArray).join();
    };

    retVal = db.<collectionName>.mapReduce(map, reduce, {out : {inline : 1}})
    print(retVal.results[0].value);
}
GetAllFields();

This function can be stored inside a js-file. Now we need to execute the function. This can be done, for example with PowerShell and the help of mongo.exe. The result of the script execution is a comma separated field list with all field-names on the 1^st -level from one collection. This is exactly the format we need for the csv export using mongoexport. Therefore we are ready to go and can call the export to a csv-file.

The following code shows a PowerShell script which retrieves the field-list and runs the export afterwards.

$fieldNames = (mongo.exe <server>/<database> <scriptFile> --quiet)
(mongoexport.exe -d <databaseName> -c <collectionName> -f $fieldNames --csv   -o <outputFile>)

Hope this will be useful for someone!

If you have simple documents having the following structure:

{
    PreName : “Daniel”,
    Name: “Weber”
}

You maybe want to rename all “Name” elements to “LastName”. To do this you can use the rename functionality from MongoDB
http://www.mongodb.org/display/DOCS/Updating#Updating-%24rename

The command for a rename should be something like this:

db.MyCollection.update( { } , { $rename : { "Name " : "LastName" } } )

When you look at the documents after running the rename query everything is fine, the field name is renamed correctly.

For the reason you run the rename command again, nothing happen (as expected) because a field with “Name” doesn’t exist anymore.

The problem occurs only when you have an index on the field you want to rename. Therefore we create the same simple document and insert an index on the “Name” property with the following command:

db.MyCollection.ensureIndex( { "Name" : 1 } )

Information about index creation can be found on
http://www.mongodb.org/display/DOCS/Indexes#Indexes-Basics

Now we run the same update command. When we have a look into the database the field name changed as expected. Then we run the rename command again. A strange thing happened. The renamed field is deleted and the “LastName” value is lost.

Therefore be careful with renames of indexed elements where a script runs the rename more than once.

What do we need to connect to MongoDB with PowerShell

The only thing we need is a MongoDB driver. I used the official C# driver which is supported by 10gen. 10gen is the company which develops MongoDB and offers support, training and consulting for MongoDB. The latest driver binaries can be downloaded at github from https://github.com/mongodb/mongo-csharp-driver/downloads

How to connect to the MongoDB server

First you need to add references to the dll’s which are provided by the MongoDB driver. Then you can establish the connection to the database. The next step is to connect to a collection. On the collection you can perform different CRUD operations.

$mongoDbDriverPath = "C:\driver\mongoDB\"
$dbName = "MyDatabase"
$collectionName = "MyCollection"
Add-Type -Path "$($mongoDbDriverPath)\MongoDB.Bson.dll"
Add-Type -Path "$($mongoDbDriverPath)\MongoDB.Driver.dll"
$db = [MongoDB.Driver.MongoDatabase]::Create("mongodb://localhost/$($dbName)")
$collection = $db[$collectionName]

Create a new document

First you need to create a BsonDocument. On the document you can add new key-value pairs by calling the add-method. As soon you finalized the new document you can store the document inside a collection with the save-method.

$document = new-object MongoDB.Bson.BsonDocument
$document.Add("PreName",[MongoDB.Bson.BsonValue]::Create("Daniel"))
$document.Add("LastName",[MongoDB.Bson.BsonValue]::Create("Weber"))
$collection.save($document)

When you use the add-method like on the sample above, MongoDB automatically creates a string value for you. If you want to create an entry with an e.g. an ObjectId, you can use the following statement.

$document.Add("UserId",[MongoDB.Bson.BsonObjectId]::Create("4f2193e0df6e251d040a6df6"))

For other object types please have a look at the MongoDB driver documentation.

Read data from collection

If you want to fetch all data from a single collection and display all objects you can use the following command.

$results = $collection.findall()
foreach ($result in $results) {
    write-host $result
}

For the reason you are only interested in a single column you can access a single columns with the following notation.

foreach ($result in $results) {
    write-host $result[“LastName”]
}

If you want to select a specific document you need to start writing a query. If you want to select all documents which have a specific LastName use the following query.

$query = [MongoDB.Driver.Builders.Query]::EQ("LastName","Weber")

For more complex scenarios you can combine different conditions to a single query. If you want to select all documents having the specified LastName and PreName use this command.

$query = [MongoDB.Driver.Builders.Query]::AND(
            [MongoDB.Driver.Builders.Query]::EQ("PreName","Daniel"),
            [MongoDB.Driver.Builders.Query]::EQ("LastName","Weber"))

The driver offer many different options to combine conditions to a single query. Not only an AND exists. After building the query, you need to find the results. This can be done by calling a find with the query as parameter.

$results = $collection.find($query)

Update data inside a collection

To update an existing document you can start with querying for an existing document. The following command search for a document with the provided ObjectId. The Id on the document is unique. Therefore we can use findOne to get this document from the collection (because we expect only a single result). To update the fetched document we use the set-method. When everything is changed don’t forget to call save. The fact that we have a document with an existing ObjectId forces MongoDB to update the document and not to create a new one.

$query = [MongoDB.Driver.Builders.Query]::EQ("_id",
            [MongoDB.Bson.BsonObjectId]::Create("4f2198f8df6e251d040a6e17"))
$result = $collection.findOne($query)
$result.Set("LastName",[MongoDB.Bson.BsonValue]::Create(“W.”))
$collection.save($result)

Delete documents from a collection

Deleting existing documents from a collection is easy. If you want to delete every document you can do this by calling removeAll. This will remove every document from the specified collection. Most of the time, you only want so delete a single document. To remove only specific data call the remove-method on the collection with a query. Every document which is returned by the query will be then be deleted.

$query = [MongoDB.Driver.Builders.Query]::EQ("PreName",
            [MongoDB.Bson.BsonValue]::Create("Daniel"))
$collection.remove($query);

Conclusion

With the C# driver it is easy to perform CRUD-Operations with MongoDB. Just have a look at the documentation of the driver if you need to perform some advanced queries. I really like how easy it is to connect to MongoDB via PowerShell.

Berwang 2011 VIEW SLIDE SHOW DOWNLOAD ALL

Cheers,

Daniel

Als ich dann das Plakat zur Tutanchamun-Austellung gesehen habe stand fest, dass ich dort hin muss. Bei den Exponaten handelt es sich ausschließlich um Nachbildungen. Meiner Meinung ist die Ausstellung trotzdem einen Besuch wert.

Leider waren die Lichtverhältnisse in der Ausstellungshalle nicht so super so dass die meisten meiner Bilder etwas verwackelt sind. Die Aufnahmen die halbwegs gut geworden sind, sind nachfolgend zu finden.

Tutanchamun VIEW SLIDE SHOW DOWNLOAD ALL

Cheers,

Daniel

Die Fahrt begann mit den am Flughafen üblichen Sicherheitschecks. Schließlich befanden wir uns während der gesamten Tour auf dem Rollfeld und sind sehr dicht an vielen Flugzeugen vorbeigefahren.

Nachdem wir den Eingang zum Rollfeld passiert hatten, standen wir mit dem Bus auch schon direkt neben einer A380. Diese Maschine auf direkter Nähe zu sehen ist wirklich beeindruckend. Man kann sich kaum vorstellen das dieser Kollos aus Stahl fliegen kann.

Während der Fahrt wurden wir außerdem mit einigen sehr Interessanten Daten “gefüttert“. Leider habe ich mir nicht viel davon gemerkt. Das was ich weiß bzw. noch ungefähr in Erinnerung habe ist folgendes:

• Frankfurt fertigt ca. 180.000 Passagiere pro Tag ab
• Die Küche für die Vorbereitung des Board-Essen ist ca. 40.000 m² groß
• Ungefähr 13 m Spülstraße zum Reinigen von Geschirr
• Die Größte A380 Ausführung kann über 1000 Personen transportieren.
• Jedes Jahr werden mehrere Tonnen Gummiabrieb von Landebahnen entfernt.
• Ca. 4000 Menschen sind für die Sicherheit zuständig.
• Nach ca. 120 Landungen muss ein Reifen Rundumerneuert werden. Nach 7 Rundumerneuerungen kann der Reifen nicht mehr verwendet werden.
• Kerosin wird direkt aus Rotterdam per Pipeline geliefert
• Nach Fertigstellung von Terminal 3 beträgt die Länge der Kofferbänder über 100 km.
• Frankfurt ist der größte deutsche Flughafen. In Europa der 3.Größte.

Diese Zahlen sind wirklich beeindruckend. Wenn man den Frankfurter Flughafen nicht selbst erlebt hat kann man sich das alles noch weniger vorstellen.

Ich will unbedingt noch die große Tour machen. Bin echt gespannt was dort noch gezeigt wird.

Nun aber genug der Worte. Hier noch ein paar Bilder.

Flughafenrundfahrt Frankfurt VIEW SLIDE SHOW DOWNLOAD ALL

Cheers,

Daniel

Im Vergleich zu meinem letzten Besuch hat sich nicht viel geändert. Man konnte auch dieses Jahr wieder einige tolle Autos und “Concept-Cars” bestaunen.

Dieses Jahr standen Autos mit Elektroantrieb im Vordergrund. Fast jeder Hersteller hatte dort etwas Neues im Angebot. Opel macht z.B. mit seinem Ampera Werbung. Der Ampera soll 40 bis 80 km rein elektrisch angetrieben zurücklegen können. Opel preist den Ampera daher als das Erste alltagstaugliche Auto an. Was meiner Meinung nach der Flopp der IAA 2011 ist. 40 km reichen vielleicht den meisten um ins Büro zu kommen aber als alltagstauglich würde ich dieses Auto damit trotzdem noch lange nicht bezeichnen.

Von Flopp zu Top. Mercedes hat es mal wieder geschafft mich zu begeistern. Zuerst einmal hat Mercedes eine riesige Halle auf der IAA. Diese erstreckte sich über mehrere Etagen. So das man am Eingang erst einmal mit der Rolltreppe nach oben gebracht werden musste. Das eigentliche Highlight war dann aber das A-concept. Ein wirklich schönes Auto. Ich kann nur hoffen das Mercedes dieses Auto so in die Produktion gibt und nicht mehr viel daran ändert. Mir jedenfalls hat es sehr gut gefallen. Interessant war auch das Mercedes einen Actros ausgestellt hatte. So konnte man mal ein bisschen “Trucker“-Luft schnuppern. Ist wirklich beeindruckend wie große diese Trucks sind. Die Sicht aus der Fahrerkabine ist ebenfalls imposant.

Neben der großen Mercedes Halle gab es noch die Halle von Audi die wirklich sehenswert war. Leider war diese total überlaufen. Im Vergleich zu Mercedes hat Audi nicht nur das innere eine Halle gestaltet. Audi hat sich eine komplette Halle auf das IAA-Gelände bauen lassen. In dem Gebäude war eine Fahrstrecke integriert. So konnte man sowohl von innen als auch von außen verschiedenste Audis vorbeifahren sehen.

Eine Fahrstrecke hatte ebenfalls BMW in die Halle integriert. Hier sind mir vor allem die 2 concept cars i3 & i8 aufgefallen. Wirklich 2 schicke Elektroflitzer. Einer der Austeller meinte sogar das nur noch kleine Veränderungen am i3 vorgenommen werden und dieser weitest gehen so wie er gerade hier steht in die Produktion geht.

Toyota hatte auch ein sehr nettes Auto am Stand stehen. Ein kleiner der auf jeder Party groß rauskommen könnte. Der Disco IQ ist ein IQ der komplett mit kleinen Spiegeln wie eine Disko-Kugel beklebt ist. Eine weitere Besonderheit ist das ausklappbare DJ-Pult das aus dem Kofferraum heraus kommt.

Aber nun genug schaut euch einfach einige meiner Bilder an.

IAA 2011 VIEW SLIDE SHOW DOWNLOAD ALL

Cheers,

Daniel