Category Archives: Web Development

Formatting Dates with Knockout.js

I am working on a couple of Silverlight projects using Microsoft Prism and found the MVVM pattern very powerful. The team at work is developing a single page HTML/Javascript application that is using Knockout as the MVVM framework. I wanted to bind a date using a custom format ‘dddd, MMMM dd, yyyy’. Since JavaScript doesn’t have great support for formatting dates I pulled in Date.js.

I am familiar with using IValueConverter in Silverlight to convert values during binding. I was really happy to find a the custom binding feature in Knockout called ‘bindingHandlers‘. I was able to write a quick bindingHandler to format the date using date.js.

Checkout the Demo

Here is the custom binding for formatting dates using date.js:

ko.bindingHandlers.dateString = {
    update: function(element, valueAccessor, allBindingsAccessor, viewModel) {
        var value = valueAccessor(),
            allBindings = allBindingsAccessor();
        var valueUnwrapped = ko.utils.unwrapObservable(value);
        var pattern = allBindings.datePattern || 'MM/dd/yyyy';
        $(element).text(valueUnwrapped.toString(pattern));
    }
}

Here is the binding in page:

Thursday, April 05, 2012
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JavaScript: Using setInterval Within an Object

I had a need to use window.setInterval(code, delay) to a call a method on a JavaScript object every few seconds to rotate some content. However, I found that once setInterval called the code in the callback ‘this’ referenced ‘window’. However, I needed ‘this’ to reference the object that was called by setInterval.

ContentTabs = {
  init: function () {
    setInterval(this.rotate, 5000);
  },
  rotate: function (){
    // this === window
  }
}

After some research I found I was having a closure issue. The solution was to use a ‘self’ variable whose scope is within the closure of the object and wrap the callback code, so it referenced the ‘self’ variable.

ContentTabs = {
  init: function () {
    var self = this;
    setInterval(function() {
       self.rotate();
    }, 5000);
  },
  rotate: function (){
    // this === ContentTabs
  }
}

DotNetNuke MVP Module Development: Tip #2 Disable AutoDataBind

In DotNetNuke MVP Module Development: Tip #1 The AutoDataBind Property I suggested to use AutoDatBind to automatically bind up the user control.  However, there are times when no binding should occur.  For example, when a Cancel button is clicked the view should not be bound.  AutoDataBind should be disabled when no model is need.

protected void cmdCancel_Click(object sender, EventArgs e)
{
    try
    {
        AutoDataBind = false;
        OnCancel();
    }
    catch (Exception exc)
    {
        Exceptions.ProcessModuleLoadException(this, exc);
    }
}

Silverlight 4 – Getting Started Plan

I have worked on a couple of small projects in Silverlight, but have never taken the opportunity to really understand the platform.  There is a new project at the office that will be using Silverlight to create interactive dashboards, so it is now time to dive into the deep end of the Silverlight pool. 

Here is my learning plan.

1. Watch Getting Started with Silverlight Development

2.
Silverlight QuickStart Tutorials
Start with “Beginning QuickStarts” tutorials 1 – 6 and then move on to “Working with Data QuickStarts” tutorials 1 – 3

3. Silverlight 4 Hands On Labs

I find that my best learning comes from reviewing good code.  I am looking for some sample source code that illustrates best practices and a quality Silverlight architecture.  If anyone knows of a good example please let me know.

How to show an InfoWindow for multiple Markers using Google Maps v3

Recently I have been working on an interactive map for the City of Aliso Viejo, CA using Google Maps.   I chose to use version 3 of the Google Maps API, because version 2 was deprecated on May 19, 2010.  I was happy to discover I no longer needed an API.  However, I did not anticipate how the changes to the MVC framework affected things.  My first task was to display multiple markers on a map, each marker having its own InfoWindow.  I found plenty of v2 examples, but could not find a really good v3 example.   Here is my solution to showing an InfoWindow for multiple markers using Google Maps v3.

In v2 GInfoWindow does not have a constructor, so an info window is displayed by calling openInfoWindow() or openInfoWindowHtml() on the GMap2 object.

GEvent.addListener(marker, 'click', function() {
    var markerPosn = new GLatLng(place["posn"][0], place["posn"][1]);
    map.openInfoWindowHtml(markerPosn ,buildPlaceInfoHtml(place),{maxWidth:275});
}); 

Things have changed significantly in Google Maps v3.  The InfoWindow now has a constructor and openInfoWindow()or openInfoWindowHtml() have been removed.  Initially I was lost trying to get each marker to show an InfoWindow with its own content.    I then read the following from the Google Maps v3 documentation about InfoWindow overlays.

InfoWindows may be attached to either Marker objects (in which case their position is based on the marker’s location) or on the map itself at a specified LatLng. If you only want one info window to display at a time (as is the behavior on Google Maps), you need only create one info window, which you can reassign to different locations or markers upon map events (such as user clicks).

Realizing I only needed one InfoWindow object. I refactored my code to create a single InfoWindow and then set  the InfoWindow content when a marker was clicked and then attach it to the appropriate marker.

var infoWindow = new google.maps.InfoWindow({});
var markers = new Array(); 

function setMarkers(map, locations, areaId) {
     for(var i = 0; i < locations.length; i++) {
         var location = locations[i];
         var latlng = new google.maps.LatLng(location.Location[0], location.Location[1]);
         var marker = new google.maps.Marker({
             position: latlng,
             map: map,
             shadow: createMarkerShadow(location.MarkerShadow),
             icon: createMarkerImage(location.MarkerImage),
             shape: markerShape,
             title: location.Name
         });
         marker.set('location', location);
         google.maps.event.addListener(marker, "click", function(event) {
            var area = this.get('location');           
            var infoWindowHtml = parseTemplate($("#MarkerTemplate").html(), { location : location} );
            infoWindow.setContent(infoWindowHtml);
            infoWindow.open(map, this);
         });
         markers.push(marker);
     }
}

function clearMarkers() {
     infoWindow.close();
     for(var i = 0; i < markers.length; i++) {
         markers[i].setMap(null);
     }
     markers.length = 0;
}

This new code iterates through an array of locations and creates a marker for each, attaches the location object, and adds an click event listener to each marker.  Attaching the location object to the marker is the key to changing the InfoWindow content when the marker is clicked. 

marker.set('location', location);

This is made possible because the InfoWindow is built on the MVCObject prototype, which exposes accessor methods.  When a marker click event fires the location object can be retrieve using the get accessor.  Now the content of the InfoWindow can be updated from the location object and attached to the marker that was clicked.

 google.maps.event.addListener(marker, "click", function(event) {
    var area = this.get('location');           
    var infoWindowHtml = parseTemplate($("#MarkerTemplate").html(), { location : location} );
    infoWindow.setContent(infoWindowHtml);
    infoWindow.open(map, this);
 });

Invoke an action between ASP.Net pages. Create a simple REST API for an ASP.NET page

Update March 1, 2013 I didn’t have a full understanding of a REST service at the time I wrote this post. I have a better understanding now and recommend using ASP.NET Web API

I needed a simple way for one page to call an action in another page.  In the spirit of a RESTful API I wanted that interaction to be called through a simple URL. 

http://localhost/Default.aspx?action=save

I initially started using a switch statement to handle the action passed in on the QueryString, but really wasn’t happy with the result.  I wasn’t interested in having to maintain a switch statement for the actions.  My first pass looked like this:

protected string Action { get; set; }

protected override void OnInit(EventArgs e)
{
    Action = Request.QueryString["action"] ?? string.Empty;
    base.OnInit(e);
}

protected void Page_Load(object sender, EventArgs e)
{
    switch (Action)
    {
        "Save":
            SaveAction();
            break;
        "Load":
            LoadAction();
            break;
        default:
            break;
    }
}

private void SaveAction()
{
    Response.Write("Save action called.");
}

private void LoadAction()
{
    Response.Write("Load action called.");
}

I decided to break out the handling of the action into a base class called ActionPage and use a event model to call the actions methods.  Following this refactoring the code behind was much easier to follow.

public partial class _Default : ActionPage
{
    protected void Page_Load(object sender, EventArgs e)
    { }

    protected override void RegisterActions()
    {
        PageActions.Add("save", SaveAction);
        PageActions.Add("load", LoadAction);
    }

    private void SaveAction()
    {
        Response.Write("Save action called.");
    }
    private void LoadAction()
    {
        Response.Write("Load action called.");
    }
}

The key was creating a ‘PageAction’ delegate that could be registered for each possible page action.  The RegisterActions method shows the action methods being registered using the PageAction delegate.  The page is now only responsible for performing the actions and no longer has to determine what action to call.   The work of reading the action from the QueryString and calling the action have been placed into the ActionPage base class.

public class ActionPage  : System.Web.UI.Page
{
    protected delegate void PageAction();
    protected readonly IDictionary<string, PageAction> PageActions = new Dictionary<string, PageAction>();
    protected string Action { get; set; }

    public ActionPage()
    {
        RegisterActions();
    }

    protected virtual void RegisterActions()
    {
    }

    protected void HandleAction(string action)
    {
        if (PageActions.ContainsKey(action))
            PageActions[action]();
    }

    protected override void OnInit(EventArgs e)
    {
        Action = Request.QueryString["action"] ?? string.Empty;
        base.OnInit(e);
    }
    protected override void OnLoad(EventArgs e)
    {
        HandleAction(Action);
        base.OnLoad(e);
    }
}

The ActionPage starts by calling RegisterActions in the constructor.  Register actions is the pages chance to register actions with the ActionPage.  The actions is then pulled from the QueryString it the OnInit method.  Then in OnLoad the action matching the one passed on the query string is called.  In this model if an invalid action is called nothing happens and the page renders normally.

SimpleRESTAPI_SampleSource.zip

Building DotNetNuke Modules Using Web Forms MVP

I have been looking for a good framework that would encourage good development practices through separation of concerns and testability in my DotNetNuke modules. I was listening to Scott Hanselman’s Hanselminutes Podcast #202 and discovered Web Forms MVPTatham Oddie and Damian Edwards have developed a framework for those us of us who are using web form’s in our projects.

Web Forms MVP provides some interesting features.  A few of the features include:

  • Composite views
  • Asynchronous tasks
  • Shared presenters
  • Presenter messaging
  • Works with HttpHandlers and web services.
  • Custom presenter factories to allow IOC integration.
    To start you will need Web Forms MVP CTP 7 if you are going to be developing for DotNetNuke.   I intially struggled with CTP 6 and through Tatham’s quick responses on the Web Forms MVP Google Group found there was a fix for this in CTP 7.  CTP 7 should be released soon, however, it looks like you should be able to build it from the source until then.

The power of the MVP pattern allows for us to have clean markup in our user control and the ability to isolate and test the logic that drives the form.  Web Forms MVP uses the supervising presenter pattern with the model loosely following the presentation model pattern.

    The following example is a  simple ‘contact us’ form.   This first pass of the contact form will just display a friendly ‘thank you’ message.  Later posts will include persistence and notification features for the contact form. 

image image

Since the view doesn’t contain any logic it can be laid out using embedded code blocks (<%= Model.FirstName %>)

<%
    panelContactUs.Visible = Model.ShowForm;
    panelMessage.Visible = !Model.ShowForm; 
%>        
<fieldset id="panelContactUs" runat="server" visible="true" class="cssform">
    <legend>Please enter your information and we will contact you soon.</legend>
    <p>
        <asp:Label ID="lblFirstName" runat="server" Text="First name:" AssociatedControlID="txtFirstName"></asp:Label>
        <asp:TextBox ID="txtFirstName" runat="server"></asp:TextBox>
    </p>
    <p>
        <asp:Label ID="lblLastName" runat="server" Text="Last name:" AssociatedControlID="txtLastName"></asp:Label>
        <asp:TextBox ID="txtLastName" runat="server"></asp:TextBox>  
    </p>
    <div style="margin-left: 150px;">
        <asp:Button ID="btnSubmit" runat="server" Text="Submit" onclick="btnSubmit_Click" />
    </div>  
</fieldset>

<div id="panelMessage" runat="server">
    <p>Dear <%=Model.FirstName %> <%=Model.LastName %>,</p>
    <p>
    Thank you for your interest in AthleticHost.  We are looking forward to working with 
    you to bring your athletic department online.  
    </p>
    <p>
    We will be contacting you soon to discuss your the specific needs of your athletic program.  
    </p>
    <p>
    Please feel free to contact us at <a href="mailto:support@athletichost.com">support@athletichost.com</a>
    </p>
    <p>
    Sincerely,<br />
    Aaron Jackson<br />
    Athletic Host
    </p>
</div>

The code behind for the control is only responsible for binding the view to the presenter and passing along the events that occur in the view, so that the presenter can react to them.  Here is the code behind for the ViewContactUs control.

[PresenterBinding(typeof(ContactUsPresenter))]
partial class ViewContactUs : PortalModuleBase, IActionable, IContactUsView
{
    protected override void OnInit(EventArgs e)
    {
        PageViewHost.Register(this, Context);
        base.OnInit(e);
    }
    protected void btnSubmit_Click(object sender, EventArgs e)
    {
        OnSubmit(txtFirstName.Text, txtLastName.Text);
    }

    public event EventHandler<SubmitContactUsEventArgs> SubmitContactUs;
    private void OnSubmit(string firstName, string lastName)
    {
        if (SubmitContactUs != null)
        {
            SubmitContactUs(this, new SubmitContactUsEventArgs
                                      {
                                          FirstName = firstName, 
                                          LastName = lastName
                                      });
        }
    }

    private ContactUsModel model;
    public ContactUsModel Model
    {
        get
        {
            if (model == null)
                throw new InvalidOperationException("The Model property is currently null, however it should have been automatically initialized by the presenter. This most likely indicates that no presenter was bound to the control. Check your presenter bindings.");

            return model;
        }
        set
        {
            model = value;
        }
    }
}

Binding the view to the presenter is normally handled by inheriting from MvpUserControl, however the ViewContactUs control needs to work with DNN.  DNN modules need to inherit from  DNN’s PortalModuleBase and since multiple inheritance is not possible in C# we have a problem.   Thankfully we can override the OnInit method and register our view with a single line of code.

protected override void OnInit(EventArgs e)
{
    PageViewHost.Register(this, Context);
    base.OnInit(e);
}

Views that don’t have any events would be complete at this point.  Views that react to events, such as, the click event on submit button in ContactUs need to be passed to the presenter.    The presenter is responsible for subscribing to the view events when it is bound to the view.  Look at the constructor of the ContactUsPresenter below.  You can see the SubmitContactUs event on the view being subscribed to by the ContactUsPresenter. 

public class ContactUsPresenter : Presenter<IContactUsView>
{
    public ContactUsPresenter(IContactUsView view) 
        : base(view)
    {
        View.SubmitContactUs += View_SubmitContactUs;
        view.Model.ShowForm = true;
        view.Model.Message = string.Empty;
    }

    public override void ReleaseView()
    {
        View.SubmitContactUs -= View_SubmitContactUs;
    }

    void View_SubmitContactUs(object sender, SubmitContactUsEventArgs e)
    {
        View.Model.FirstName = e.FirstName;
        View.Model.LastName = e.LastName;
        View.Model.Message = e.FirstName + " " + e.LastName;
        View.Model.ShowForm = false;
    }
}

Finally, a look at the unit test that was written for the presenter.  I choose to use xUnit and Moq to handle the testing.    Since the view implements the IContactUsView interface the unit test can mock the view and allow for the presenter to be tested without dependencies on DNN.   In fact, this presenter could be reused on any other web forms project.

[Fact]
public void ContactUsPresenter_Sets_Message_OnSubmit()
{
    // Arrange
    var view = new Mock<IContactUsView>();
    view.SetupAllProperties();
    var presenter = new ContactUsPresenter(view.Object);

    // Act
    view.Raise(v => v.Load += null, new EventArgs());
    view.Raise(v => v.SubmitContactUs += null, 
        new SubmitContactUsEventArgs("Chester", "Tester", 
            "ctester@test.com", "http://www.test.com", 
            "This is a test of the emergancy broadcast system..."));  
    presenter.ReleaseView();

    // Assert
    Assert.Contains("Chester Tester", view.Object.Model.Message);
    Assert.Equal("Chester", view.Object.Model.FirstName);
    Assert.Equal("Tester", view.Object.Model.LastName);
    Assert.False(view.Object.Model.ShowForm);
}

Download the ContactUs module source.

YUI Compressor and NAnt

I have been working on creating a DotNetNuke Skin for AthleticHost.com.   In order to simplify deployment of the skin I wanted to add it as an extension to DNN rather that upload it via FTP.   I choose to use NAnt to build the extension install file.   In an effort to increase page performance I decided that the CSS and JavaScript files should be compressed and choose the YUI Compressor for the job.

I created two targets.  One to minify the JavaScript and another for the CSS.

<target name="JavaScript.minify">
<foreach item="File" property="filename">
  <in>
    <items>
      <include name="${temp.dir}/**/js/**/*.js"/>
    </items>
  </in>
  <do>
    <echo message="${filename}" />
    <exec program="java" workingdir="${YUICompressor.dir}">
      <arg value="-jar" />
      <arg value="yuicompressor-2.4.2.jar" />
      <arg value="--type" />
      <arg value="js" />
      <arg value="-o" />
      <arg value="${filename}.min" />
      <arg value="${filename}" />
    </exec>
    <move file="${filename}.min" tofile="${filename}" overwrite="true" />
  </do>
</foreach>
</target>
<target name="Css.minify">
<foreach item="File" property="filename">
  <in>
    <items>
      <include name="${temp.dir}/**/*.css"/>
    </items>
  </in>
  <do>
    <echo message="${filename}" />
    <exec program="java" workingdir="${YUICompressor.dir}">
      <arg value="-jar" />
      <arg value="yuicompressor-2.4.2.jar" />
      <arg value="--type" />
      <arg value="css" />
      <arg value="-o" />
      <arg value="${filename}.min" />
      <arg value="${filename}" />
    </exec>
    <move file="${filename}.min" tofile="${filename}" overwrite="true" />
  </do>
</foreach>
</target>

The “Deploy” target then calls the “Css.minify” and “Javascript.minify”

<call target="JavaScript.minify" />
<call target="Css.minify" />

Download the full NAnt script.

Resouces:
http://developer.yahoo.com/yui/compressor/
http://nant.sourceforge.net/

AthleticHost.com will be using DotNetNuke

athletichost_logo_143    DotNetNuke-Logo

I have been working on site for Timberline High School Athletics for the last four years.  The site has become an important tool for the athletic department and used by the parents and student athletes to get news and information about the schools sports programs.

Through my experience with Timberline I have discovered that many high school athletic programs do not have a website or have a very poor website that is not well maintained.   I have been working over the past several months to create a hosting service that will provide websites for high school athletic programs.  The websites will be designed to be easily maintained by athletic directors, coaches, and team parents. 

AthleticHost.com will be using DotNetNuke (DNN) as the core platform for these sites.  DNN was chosen for the following reasons:

  • The ability to have many websites (a.k.a. portals) on a single DNN installation.
  • Site templates will allow for new sites to be quickly created.
  • Built in hosting model that includes security and payment features.
  • Skinning system that allows each portal to have its own look-and-feel.   This is important because many niche web hosts sites all look the same.  I want each school to have it’s own look-and-feel.
  • A security model that will allow separate security configurations for the athletic director, coaches, and team parents.
  • A good set of core modules.

Hosting at AthleticHost.com will be available May 1, 2010.

Too cheap to hire a graphic designer

I am donating my time to rebuild wolvesathletics.com in ASP.NET using DotNetNuke.   It will be a significant upgrade for Timberline High School’s athletics website and offer them better capabilities for editing for coaches and team parents.  Since I am donating the time I didn’t want to hire a designer, so having no formal design experience I gave it a shot.

I am very interested in getting feedback about the design and what I can do to polish it up.  Please leave comments on this with your ideas.

Review the Wolves Athletics design concepts.