IRowConsumer Interface

NOTE: This API is now obsolete.

Enables a Web Part to communicate with a Web Part that implements the IRowProvider interface (or that supports a suitable transformer) to work with a row of data.

Namespace:  Microsoft.SharePoint.WebPartPages.Communication
Assembly:  Microsoft.SharePoint (in Microsoft.SharePoint.dll)

[ObsoleteAttribute("Use System.Web.UI.WebControls.WebParts.IWebPartRow instead")]
public interface IRowConsumer

The IRowConsumer interface should be implemented in Web Parts that need to consume a collection of data that can be characterized as a row, such as a row in a table. The IRowConsumer interface has the ability to receive initialization arguments from the provider Web Part. When connecting a Web Part that implements the IRowConsumer interface to a IRowProvider Web Part, the connection is direct, so no transformer dialog box will be displayed. To use the passed values appropriately, the consuming Web Part may need to be designed with an understanding of the schema of the data being sent by the provider Web Part.

The following code example shows a simple Web Part that implements the IRowConsumer interface and supports running its connection implementation only on the server. It can be connected to another Web Part that implements the IRowProvider interface on the server. Its user interface displays the row of values received from the IRowProvider Web Part.

There are seven steps specific to making this a connectable Web Part. These steps are numbered and commented in the following code sample.

// Common .NET required namespaces
using System;
using System.ComponentModel;
using System.Web.UI;

// Web Part required namespaces
using Microsoft.SharePoint.WebPartPages;
using System.Xml.Serialization;
using System.Web.UI.WebControls;

// Code Access Security namespaces
using System.Security;
using Microsoft.SharePoint.Utilities;

// DataRow namespace
using System.Data;

//Step #1: Make a reference to the Communication namespace.
using Microsoft.SharePoint.WebPartPages.Communication;

namespace ConnectionCodeSamples
{
    //Step #2: Inherit from the WebPart base class and implement the IRowConsumer interface.
    public class ServerSideRowConsumer : WebPart, IRowConsumer
    {    

        // Declare variables for keeping track of connection state.
        private bool _connected = false;
        private string _connectedWebPartTitle = string.Empty;
        private string _registrationErrorMsg = "An error has occurred trying to register your connection interfaces.";
        private bool _registrationErrorOccurred = false;
        private string _notConnectedMsg = "NOT CONNECTED. To use this Web Part connect it to a Row Provider Web Part.";
        private string _selectRowMsg = "Please select a row from the connected Row Provider Web Part.";

        // Declare variables for Web Part user interface.
        private string _connectedWebPartLabel = "Connected to Web Part";
        private string _selectionStatus = string.Empty;

        // Declare variables for row information.
        private string[] _rowFieldDisplayNames;
        DataRow[] _rowFieldValues = new DataRow[1];

        // Step #3: Override the EnsureInterfaces() method and call the 
        // RegisterInterface method.
        public override void EnsureInterfaces()
        {
            // If your Web Part is installed in the bin directory and 
            // the Code Access Security (CAS) setting doesn't 
            // allow Web Part Connections, an exception will be thrown. 
            // To allow your Web Part to behave 
            // well and continue working, a try/catch block should be 
            // used when attempting to register interfaces.
            // Web Part Connections will only work if the level 
            // attribute of the <trust> tag in the 
            // web.config file is set to WSS_Minimal, WSS_Medium, or 
            // Full. By default a new SharePoint site
            // is installed with the trust level set to WSS_Minimal.
            try
            {
                // Register the IRowConsumer interface.
                // <param name="interfaceName">Friendly name of the 
                // interface that is being implemented.</param>
                // <param name="interfaceType">Specifies which 
                // interface is being implemented.</param>
                // <param name="maxConnections">Defines how many times 
                // this interface can be connected.</param>
                // <param name="runAtOptions">Determines where the 
                // interface can run.</param>
                // <param name="interfaceObject">Reference to the 
                // object that is implementing this interface.</param>
                // <param name="interfaceClientReference">Name used to 
                // reference the interface on the client. 
                // This is a server side example so the value is set to 
                // empty string.</param>
                // <param name="menuLabel">Label for the interface 
                // which appears in the UI</param>
                // <param name="description">Description of the 
                // interface which appears in the UI</param>
                // <param name="allowCrossPageConnection">Specifies if 
                // the interface can connect to a Web Part
                // on a different page. This is an optional parameter 
                // with a default of false. Note that only some 
                // server side interfaces are allowed to connect across 
                // pages by the Web Part infrastructure. 
                // The IRowConsumer interface is not allowed to connect 
                // across pages.</param>
                RegisterInterface("MyRowConsumerInterface",                 //InterfaceName    
                    InterfaceTypes.IRowConsumer,                            //InterfaceType
                    WebPart.LimitOneConnection,                             //MaxConnections
                    ConnectionRunAt.Server,                                 //RunAtOptions
                    this,                                                   //InterfaceObject
                    "",                                                     //InterfaceClientReference
                    "Consume Row From",                                     //MenuLabel
                    "Consumes a single row from another Web Part.");        //Description
            }
            catch(SecurityException se)
            {
                _registrationErrorOccurred = true;
            }
        }


        // Step #4: Override the CanRunAt() method.
        // CanRunAt() is called by the Web Part infrastructure during 
        // the ASP.NET PreRender event
        // to determine where the Web Part can run based on its current 
        // configuration.
        public override ConnectionRunAt CanRunAt()
        {
            // This Web Part can run on the server.
            return ConnectionRunAt.Server;
        }


        // Step #5: Override the PartCommunicationConnect() method.
        // PartCommunicationConnect() is called by the Web Part 
        // infrastructure to notify the Web Part that it
        // is connected during the ASP.NET PreRender event. Relevant 
        // information is passed to the part such as 
        // the interface it is connected over, the Web Part it is being 
        // connected to, and where the part will be running, 
        // either client or server side. 
        // <param name="interfaceName">Friendly name of the interface 
        // that is being connected</param>
        // <param name="connectedPart">Reference to the other Web Part 
        // that is being connected to</param>
        // <param name="connectedInterfaceName">Friendly name of the 
        // interface on the other Web Part</param>
        // <param name="runAt">Where the interface should 
        // execute</param>
        public override void PartCommunicationConnect(string interfaceName,
            WebPart connectedPart,
            string connectedInterfaceName,
            ConnectionRunAt runAt)
        {
            // Keep track of the connection state.
            if (interfaceName == "MyRowConsumerInterface")
            {
                _connected = true;
                _connectedWebPartTitle = SPEncode.HtmlEncode(connectedPart.Title);
            }
        }

        // Step #6: Implement the RowProviderInit event handler.
        // The connected provider part(s) will call this method during 
        // its PartCommunicationInit phase
        // to pass initialization information to the consumer Web Part.
        // <param name="sender">Reference to the Consumer Web 
        // Part</param>
        // <param name="rowProviderInitEventArgs">The args passed by 
        // the provider Web Part</param>
        public void RowProviderInit(object sender, RowProviderInitEventArgs rowProviderInitEventArgs)
        {
            // Store the field list
            _rowFieldDisplayNames = rowProviderInitEventArgs.FieldDisplayList;

        }

        // Step #7: Implement the RowReady event handler.
        // The connected provider part(s) will call this method during 
        // its PartCommunicationMain phase
        // to pass their primary data to the consumer Web Part.
        // <param name="sender">Reference to the provider Web 
        // Part</param>
        // <param name="rowReadyEventArgs">The args passed by the 
        // provider Web Part</param>
        public void RowReady(object sender, RowReadyEventArgs rowReadyEventArgs)
        {
            // Store the row values.
            if(rowReadyEventArgs.Rows!= null)
            {
               if(rowReadyEventArgs.Rows[0]!= null)
               {
                  _rowFieldValues[0] = rowReadyEventArgs.Rows[0];
                }
            }

            _selectionStatus = rowReadyEventArgs.SelectionStatus;
        }

        // Render the Web Part.
        protected override void RenderWebPart(HtmlTextWriter output)
        {
            // Check for connection interface registration error.
            if (_registrationErrorOccurred)
            {
                output.Write(_registrationErrorMsg);
                return;
            }

            // Check if connected.
            if(_connected)
            {
                int index = 0;
                string fieldName;

                // Check if a row has been selected.
                if (_selectionStatus == "Standard")
                {
                    // Generate results table from received row.
                    output.RenderBeginTag(HtmlTextWriterTag.Table);
                    for (index = 0; index < _rowFieldDisplayNames.Length; index++)
                    {
                        fieldName = _rowFieldDisplayNames[index];
                    
                        output.RenderBeginTag(HtmlTextWriterTag.Tr);
                        output.RenderBeginTag(HtmlTextWriterTag.Td);
                        output.RenderBeginTag(HtmlTextWriterTag.B);
                        output.Write(fieldName + ": ");
                        output.RenderEndTag(); //End <B>
                        output.RenderEndTag(); //End <TD>

                        output.RenderBeginTag(HtmlTextWriterTag.Td);
                        output.Write(_rowFieldValues[0][fieldName].ToString());
                        output.RenderEndTag(); //End <TD>
                        output.RenderEndTag(); //End <TR>
                    }
                    output.RenderEndTag(); //End <Table>
                }
                else
                {
                    output.RenderBeginTag(HtmlTextWriterTag.B);
                    output.Write(_selectRowMsg);
                    output.RenderEndTag();
                }


                // Line break.
                output.RenderBeginTag(HtmlTextWriterTag.Br);
                output.RenderEndTag();

                // Render the connected Web Part title.
                output.Write(_connectedWebPartLabel + ": ");
                output.RenderBeginTag(HtmlTextWriterTag.I);
                output.Write(_connectedWebPartTitle);
                output.RenderEndTag();
                output.Write("<br>");

            }
            else
            {
                // The Web Part isn't connected.
                output.Write(_notConnectedMsg);
            }
        }
    }
}


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