Ajax Web Parts Part 4 - Dynamic Web Part Connections

Posts In This Series:

Introduction - ASP.NET AJAX and Web Parts
Ajax Web Parts Part 1 - Drag and Drop
Ajax Web Parts Part 2 - Web Part Connections
Ajax Web Parts Part 3 - Dynamic Web Parts
Ajax Web Parts Part 4 - Dynamic Web Part Connections


Download the source - Part 1
Download the source - Part 2
Download the source - Part 3
Download the source - Part 4

Introduction

Currently the dynamically created Web Parts (described in part 3) cannot be moved between zones. In addition, doing a postback results in more dynamically generated Web Parts appearing. This occurs because the Web Part Manager assigns each dynamically created Web Part a random ID when its AddWebPart() function is called. To fix this problem we need a Web Part Manager that doesn’t assign random IDs and, luckily for us, Lee Dale has created just what we’re after.

Modifying Lee’s code slightly, so that it derives from the Preview DLL’s WebPartManager, rather than the standard WebPartManager (to ensure cross browser drag and drop), gives the following:

namespace AjaxWebParts.Controls
{
  public class DynamicWebPartManager 
  : Microsoft.Web.Preview.UI.Controls.WebParts.WebPartManager
  {
    public void AddDynamicWebPart(WebPart webPart,
                Microsoft.Web.Preview.UI.Controls.WebParts.WebPartZone zone)
    {
      Internals.AddWebPart(webPart);
      Internals.SetZoneID(webPart, zone.ID);
    }
  }
}

To use this new Web Part Manager we need to make the following changes:

In our DynamicWebParts class, make the following changes:

1. change the WebPartManager alias at the top of the line to become the following:

using WebPartManager = AjaxWebParts.Controls.DynamicWebPartManager;

2. change the addition of the dynamically created Web Part to the Web Part Zone to use the DynamicWebPartManger’s function. So the current

return itsManager.AddWebPart(genericWebPart, zone, 0);

is replaced by:

itsManager.AddDynamicWebPart(genericWebPart, zone);
return genericWebPart;  

In the default.aspx page the following changes are required:

1. Add the following to the set of namespace registrations:

<%@ Register Namespace="AjaxWebParts.Controls" TagPrefix="awp" %>

2. Change the reference to the Web Part Manager from “cc1:WebPartManager” to “awp:DynamicWebPartManager”

After these changes have been made everything should now work as it should: the dynamically created Web Parts should now be able to be dragged between zones and multiple Web Parts should not appear when postbacks occur. All that is required now is to implement the connection between the dynamic Web Parts.

Creating Dynamic Web Part Connections

Once dynamic Web Parts exist, with non-random ID values, creating the connections between them is relatively straightforward. We simply need to get the connection point from each Web Part and then, if a connection can be made between the Web Parts, simply create a connection that joins the two connection points.

We therefore need to add a new function to our DynamicWebParts class to create the Web Part connection, as follows:

<br />/// <summary><br />/// Form a connection between the suplied provider and consumer web parts<br />/// </summary> <br />/// <param name="aProvider">the provider web part</param><br />/// <param name="aConsumer">the consumer web part</param> <br />public void FormWebPartConnection(WebPart aProvider, WebPart aConsumer)<br />{<br /> if (aProvider != null && aConsumer != null)<br /> {<br /> // get the connection points collections for each web part<br /> ProviderConnectionPointCollection providerConnectionPoints = itsManager.GetProviderConnectionPoints(aProvider);<br /> ConsumerConnectionPointCollection consumerConnectionPoints = itsManager.GetConsumerConnectionPoints(aConsumer);<br /><br /> // each web part only has a single connection point, so take the first one of each<br /> ProviderConnectionPoint provPoint = providerConnectionPoints[0];<br /> ConsumerConnectionPoint connPoint = consumerConnectionPoints[0];<br /><br /> if (provPoint != null && connPoint != null)<br /> {<br /> // check that these web parts can be connected<br /> if (itsManager.CanConnectWebParts(aProvider, provPoint, aConsumer, connPoint))<br /> {<br /> // create the connection<br /> WebPartConnection newconn = new WebPartConnection();<br /> newconn.ID = "AutoConnection";<br /> newconn.ConsumerID = aConsumer.ID;<br /> newconn.ProviderID = aProvider.ID;<br /> itsManager.StaticConnections.Add(newconn);<br /> }<br /> }<br /> }<br />}<br />

Finally we need to call this function from our default.aspx.cs code-behind file. The Page_Init() function now becomes:

<br />protected void Page_Init(object sender, EventArgs e)<br />{<br /> // create an instance of the dynamic web part class<br /> DynamicWebParts dynamicWebParts = new DynamicWebParts(this);<br /> dynamicWebParts.Manager = WebPartManager1;<br /><br /> // create 2 web parts<br /> WebPart provider = dynamicWebParts.AddWebPartToZone("WebPartZone1", <br /> "UserControls/Provider.ascx", <br /> "Dynamic Provider");<br /> WebPart consumer = dynamicWebParts.AddWebPartToZone("WebPartZone2", <br /> "UserControls/Consumer.ascx", <br /> "Dynamic Consumer");<br /><br /> // create a connection between the web parts<br /> dynamicWebParts.FormWebPartConnection(provider, consumer);<br />}<br />

Now, when the Web Page is run, the dynamically generated Web Parts will be connected. Typing a value into the dynamic provider's text box and clicking the button will result in the value being displayed in the dynamically created consumer Web Part.

Creating Dynamic Web Part Zones

Now that we can dynamically create Web Parts, lets move on to create the rest of the page dynamically, starting with the Web Part Zones.
This is very straightforward – it’s simply a case of creating an instance of a WebPartZone and adding it to the page (note that the WebPartZone that gets created is from the Preview DLL, due to the alias that was declared).

The DynamicWebParts class member function therefore appears as follows:

<br />/// <summary><br />/// Create a new web part zone and give it the supplied title<br />/// (the title is also used as the ID of the zone)<br />/// </summary><br />/// <param name="aZoneTitle"></param><br />/// <returns></returns><br />public WebPartZone CreateWebPartZone(string aZoneTitle)<br />{<br /> WebPartZone webPartZone = new WebPartZone();<br /> webPartZone.ID = aZoneTitle.Replace(" ", "");<br /> webPartZone.HeaderText = aZoneTitle;<br /> return webPartZone;<br />} <br />


Similarly, we can create the WebPartManager:

<br />/// <summary><br />/// Create a new dynamic web part manager<br />/// </summary><br />/// <returns></returns><br />public DynamicWebPartManager CreateWebPartManager()<br />{<br /> DynamicWebPartManager webPartManager = new DynamicWebPartManager();<br /> webPartManager.ID = "WebPartManager1";<br /> return webPartManager;<br />}<br />


and the UpdatePanel:

<br />/// <summary><br />/// Create a new update panel with the supplied ID<br />/// </summary><br />/// <param name="aID"></param><br />/// <returns></returns><br />public UpdatePanel CreateUpdatePanel( string aID )<br />{ <br /> UpdatePanel updatePanel = new UpdatePanel();<br /> updatePanel.ID = aID;<br /> return updatePanel;<br />}<br />

Since all the page components can now be created dynamically, the static components in the page markup are no longer required. This page therefore simplifies down to:

<br /> <form id="form1" runat="server"><br /> <div><br /> <h2>Click and hold the Web Part title to drag it to the second Web Part Zone:</h2> <br /> <asp:button id="ResetButton" runat="server" text="Reset" onclick="ResetButton_Click"> <br /> <asp:scriptmanager id="ScriptManager1" runat="server"> <br /> <asp:placeholder id="PlaceHolder1" runat="server"><br /> </div><br /> </form><br />

Note that a PlaceHolder component has been added to give us somewhere to add our dynamic components.

In the Default.aspx.cs code behind file the Page_Init function now becomes:

<br />protected void Page_Init(object sender, EventArgs e)<br />{<br /> // create an instance of the dynamic web part class<br /> DynamicWebParts dynamicWebParts = new DynamicWebParts(this);<br /><br /> // create a new update panel<br /> UpdatePanel updatePanel = dynamicWebParts.CreateUpdatePanel("DynamicUpdatePanel");<br /><br /> // add the web part manager to the update panel<br /> updatePanel.ContentTemplateContainer.Controls.Add(dynamicWebParts.Manager);<br /><br /> // add 2 web part zones to the update panel<br /> WebPartZone dynamicZone1 = dynamicWebParts.CreateWebPartZone("Dynamic Zone 1");<br /> updatePanel.ContentTemplateContainer.Controls.Add(dynamicZone1);<br /> WebPartZone dynamicZone2 = dynamicWebParts.CreateWebPartZone("Dynamic Zone 2");<br /> updatePanel.ContentTemplateContainer.Controls.Add(dynamicZone2);<br /><br /> // add the update panel to the page<br /> PlaceHolder1.Controls.Add(updatePanel);<br /><br /> // create 2 web parts<br /> WebPart provider = dynamicWebParts.AddWebPartToZone(dynamicZone1.ID, <br /> "UserControls/Provider.ascx", <br /> "Dynamic Provider");<br /> WebPart consumer = dynamicWebParts.AddWebPartToZone(dynamicZone2.ID, <br /> "UserControls/Consumer.ascx", <br /> "Dynamic Consumer");<br /><br /> // create a connection between the web parts<br /> dynamicWebParts.FormWebPartConnection(provider, consumer);<br />}<br />

And, since the page markup no longer defines a WebPartManager, this needs to obtained dynamically when needed. So the Page_load function now changes to become:

<br />protected void Page_Load(object sender, EventArgs e)<br />{<br /> if (!Page.IsPostBack)<br /> {<br /> // set the display mode to "Design" to allow drag and drop<br /> WebPartManager manager = WebPartManager.GetCurrentWebPartManager(this);<br /> if (manager != null)<br /> {<br /> WebPartDisplayMode mode = manager.SupportedDisplayModes["Design"];<br /> if (mode != null)<br /> {<br /> manager.DisplayMode = mode;<br /> }<br /> }<br /> }<br />}<br />


Click here to see this in action.


Putting this all together results in an ASP.NET AJAX page, featuring 2 Web Part Zones and 2 dragable, connected, Web Parts. Everything has now been created dynamically and is therefore just what’s required for populating tab pages.