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IFilterConsumer interface

NOTE: This API is now obsolete.

Used to consume a filter expression from a Web Part that has implemented an IFilterProvider interface.

Namespace:  Microsoft.SharePoint.WebPartPages.Communication
Assembly:  Microsoft.SharePoint (in Microsoft.SharePoint.dll)
[ObsoleteAttribute("Use System.Web.UI.WebControls.WebParts.IWebPartParameters instead")]
public interface IFilterConsumer

The IFilterConsumer interface should be used with parts that need to consume a collection of one or more filter values. The event handlers of IFilterConsumer were designed for the purpose of setting and clearing multiple filter values. The IFilterConsumer part has the ability to send initialization arguments to the provider part. The IFilterConsumer can be connected to the IFilterProvider and IRowProvider interfaces. When connecting the IFilterConsumer to IFilterProvider, this is a direct connection so no transformer dialog will be displayed. To appropriately use the passed values, the consuming part may need to be designed with an understanding of the data passed by the provider. When connecting the IFilterConsumer to IRowProvider, a transformer dialog will be displayed which allows an end user to map the column in the row to the filter input. Only one value can be mapped, but it gives the end user the ability to change the filter mapping at any time. Server side implementations of IFilterConsumer can also be connected to parts on a different page by using an HTML editor compatible with Microsoft SharePoint Foundation, such as Microsoft SharePoint Designer.

The following code example shows a server-side IFilterConsumer Web Part. It can be connected to another Web Part which implements the IFilterProvider or IRowProvider interface on the server. The IFilterConsumer Web Part displays a list which can be filtered by the values sent by a provider Web Part.

There are 11 steps specific to making this a connectable Web Part. These steps are numbered and commented in the following code example.

For more information on creating a connectable Web Part, see Creating a Connectable Web Part.

// 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;

// DataGrid and user interface namespaces
using System.Data;
using System.Drawing;

// Step #1: Reference the Communication namespace.
using Microsoft.SharePoint.WebPartPages.Communication;

namespace ConnectionCodeSamples
{
    // Step #2: Implement the IFilterConsumer interface.
    public class ServerSideFilterConsumer : WebPart, IFilterConsumer
    {    
        // Step #3: Declare the IFilterConsumer event.
        // Because this class implements the IFilterConsumer interface, 
        // it must declare the interface member FilterConsumerInit. 
        
        public event FilterConsumerInitEventHandler FilterConsumerInit;

        // 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 filter this Web Part connect it to a Filter or Row Provider Web Part.";

        // Declare variables for Web Part user interface.
        private string _connectedWebPartLabel = "Connected to Web Part";
        private string _convertedRowFilterLabel ="Converted Row Filter";
        private DataGrid _dataGrid;
        private string _rowFilterExpression = string.Empty;
        private TextBox _cachedRowFilter;

        // Declare variables for filter field information.
        private string[] _filterFieldNames;
        private string[] _filterFieldDisplayNames;
        private string FieldLabel = "FilterField";
        private string ValueLabel = "FilterValue";

        // Step #4: Override EnsureInterfaces method and call RegisterInterface method.
        // EnsureInterfaces() is called by the Web Part infrastructure 
        // during the ASP.NET PreRender event 
        // and allows the part to register all of its connection 
        // interfaces.

        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 IFilterConsumer 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 IFilterConsumer interface is allowed to connect 
                // across pages.</param>
                RegisterInterface("MyFilterConsumerInterface",                 //InterfaceName    
                    InterfaceTypes.IFilterConsumer,                            //InterfaceType
                    WebPart.LimitOneConnection,                                //MaxConnections
                    ConnectionRunAt.Server,                                    //RunAtOptions
                    this,                                                      //InterfaceObject
                    "",                                                        //InterfaceClientReference
                    "Consume Filter From",                                     //MenuLabel
                    "Consumes a Filter from another Web Part.",                //Description
                    true);                                                     //allowCrossPageConnection
            }
            catch(SecurityException se)
            {
                _registrationErrorOccurred = true;
            }
        }

        // Step #5: Override 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 #6: Override 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)
        {
            //Check if this is my particular Filter interface
            if (interfaceName == "MyFilterConsumerInterface")
            {
                //Keep track of the Connection
                _connected = true;
                _connectedWebPartTitle = SPEncode.HtmlEncode(connectedPart.Title);
            }
        }

        // Step #7: Override PartCommunicationInit method.
        // PartCommunicationInit() is called by the Web Part 
        // infrastructure during the ASP.NET PreRender event
        // to allow the part to pass initialization information to the 
        // other connected parts.
        // It is important to always pass initialization information. 
        // Some parts may not behave properly if this initialization 
        // information is not received.
        public override void PartCommunicationInit()
        {
            // If the connection wasn't actually formed then don't want 
            // to send Init event
            if(_connected)
            {
                // Ensure that all of the Web Part's controls are 
                // created
                // The _filterFieldNames and _filterFieldDisplayNames 
                // are set during EnsureChildControls()
                EnsureChildControls();

                // If there is a listener, fire the FilterConsumerInit 
                // event
                if (FilterConsumerInit != null)
                {
                    // Create the FilterConsumerInitEventArgs object 
                    // for the FilterConsumerInit event.
                    FilterConsumerInitEventArgs filterConsumerInitArgs = new FilterConsumerInitEventArgs();
                    
                    // Set the field names.
                    filterConsumerInitArgs.FieldList = _filterFieldNames;
                    filterConsumerInitArgs.FieldDisplayList = _filterFieldDisplayNames;
                    
                    // Fire the FilterConsumerInit event.
                    FilterConsumerInit(this, filterConsumerInitArgs);
                }
            }
        }

        // Step #8: Override the GetInitEventArgs method.
        // GetInitEventArgs() is called by the Web Part infrastructure 
        // during the ASP.NET PreRender event to gather the 
        // necessary information it needs to build the transformer 
        // dialog. The transformer dialog is needed when connecting 
        // different interfaces such as IRowProvider
        // to ICellConsumer. The transformer dialog allows the user to 
        // map the fields between the interfaces. The 
        // GetInitEventArgs()method only needs to be implemented for 
        // interfaces that can participate in a transformer, which are 
        // the following:
        // ICellConsumer, IRowProvider, IFilterConsumer, 
        // IParametersOutProvider, IParametersInConsumer.
        // <param name="interfacename">Name of interface on which the 
        // Web Part infrastructure is requesting information</param>
        // <returns>An InitEventArgs object</returns>
        public override InitEventArgs GetInitEventArgs(string interfaceName)
        {
            // Check if this is my particular cell interface.
            if (interfaceName == "MyFilterConsumerInterface")
            {
                // Ensure that all of the Web Part's controls are 
                // created.
                //The _filterFieldNames and _filterFieldDisplayNames 
                // are set during EnsureChildControls()
                EnsureChildControls();

                // Create the FilterConsumerInitEventArgs object for 
                // the FilterConsumerInit event.
                FilterConsumerInitEventArgs filterConsumerInitArgs = new FilterConsumerInitEventArgs();
                    
                // Set the field names
                filterConsumerInitArgs.FieldList = _filterFieldNames;
                filterConsumerInitArgs.FieldDisplayList = _filterFieldDisplayNames;
                    
                // return the FilterConsumerInitEventArgs. 
                return(filterConsumerInitArgs);
            }
            else
            {
                return(null);
            }
        }

        // Step #9: Implement the SetFilter event handler.
        // The connected provider part will call this method during its 
        // PartCommunicationMain phase
        // to set the filter on the consumer Web Part.
        // <param name="sender">Provider Web Part</param>
        // <param name="SetFilterArgs">The args passed by the 
        // Provider</param>
        public void SetFilter(object sender, SetFilterEventArgs setFilterEventArgs)
        {
            // Ensure that all of the Web Part's controls are created.
            EnsureChildControls();

            // Convert FilterExpression to the DataTable RowFilter 
            // syntax.
            if(setFilterEventArgs.FilterExpression != null)
            {
                
                // Parse the filter information.
                string[] values = setFilterEventArgs.FilterExpression.Split(new Char[] {'&'});
                if (values.Length > 1)
                {
                    int j = 1;  //counts the number of Field/Value pairs
                    string filterField = string.Empty;
                    string filterValue = string.Empty;
                    string filterAnd = " AND ";
                    _rowFilterExpression = string.Empty;

                    for(int i=0; i < values.Length; i++)
                    {
                        // Clear values.
                        filterField = string.Empty;
                        filterValue = string.Empty;

                        // Create label portion of name/value pairs.
                        string currField, currValue;
                        currField = FieldLabel + j + "=";
                        currValue = ValueLabel + j + "=";
                        j++;  
                    
                        // Extract just the field name by replacing
                        // the rest of the string with string.Empty.
                        filterField = filterField + values[i].Replace(currField, string.Empty);
                    
                        // Move to next item in the array which is 
                        // the value component.
                        i++;
                
                        // Extract just the Value by replacing the 
                        // rest of the string with string.Empty.
                        filterValue = filterValue + values[i].Replace(currValue, string.Empty);

                        // Contruct the row filter expression.
                        _rowFilterExpression += filterField + "=" + "'" + filterValue + "'" + filterAnd;

                    }
                    // Trim Off the trailing 'And'.
                    if (_rowFilterExpression.Length != 0)
                        _rowFilterExpression = _rowFilterExpression.Substring(0,_rowFilterExpression.Length - filterAnd.Length);

                    // Store _rowFilterExpression for use by 
                    // NoFilter event.
                    _cachedRowFilter.Text = _rowFilterExpression;
                }
            }
        }

        // Step #10: Implement ClearFilter event handler.
        // The connected provider part will call this method during 
        // its PartCommunicationMain phase
        // to remove the filter on the consumer Web Part.
        // <param name="sender">Provider Web Part</param>
        // <param name="eventArgs">The Event Arguments</param>
        public void ClearFilter(object sender, EventArgs eventArgs)
        {
            // Ensure that all of the Web Part's controls are created.
            EnsureChildControls();

            // Clear the filter on the DataTable.
            _rowFilterExpression = string.Empty;

            // Clear out the cached row filter expression.
            _cachedRowFilter.Text = string.Empty;
        }

        // Step #11: Implement NoFilter event handler.
        // The connected provider part will call this method during 
        // its PartCommunicationMain phase to indicate there is no 
        // change in the filter. This allows the consumer part to 
        // display its cached data instead of recalculating the 
        // filter expression or potentially hitting a database again. 
        // <param name="sender">Provider Web Part</param>
        // <param name="eventArgs">The Event Arguments</param>
        public void NoFilter(object sender, EventArgs eventArgs)
        {
            // Ensure that all of the Web Part's controls are created.
            EnsureChildControls();

            // No change in the filter so use cached _cachedRowFilter.
            _rowFilterExpression = _cachedRowFilter.Text;

        }

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

            // Ensure that all of the Web Part's controls are created.
            EnsureChildControls();

            // Row filter expression supplied by provider. 
            output.RenderBeginTag(HtmlTextWriterTag.B);
            output.Write(_convertedRowFilterLabel + ": ");
            output.RenderEndTag();
            output.Write(_rowFilterExpression);

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

            // Set filter.
            ((DataTable)_dataGrid.DataSource).DefaultView.RowFilter = _rowFilterExpression;
            _dataGrid.DataBind();

            // Render the DataGrid control.
            _dataGrid.RenderControl(output);

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

            // Hidden Row Filter TextBox stores _rowFilterExpression.
            _cachedRowFilter.RenderControl(output);

            // Check if connected.
            if(_connected)
            {
                // Render 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);
            }
        }

        // Create Web Part user interface controls.
        protected override void CreateChildControls()
        {
            // Create hidden textbox to store _rowFilterExpression.
            _cachedRowFilter = new TextBox();
            _cachedRowFilter.ID = "CachedRowFilter";
            _cachedRowFilter.Visible = false;
            Controls.Add(_cachedRowFilter);

            // Create the DataGrid.
            _dataGrid = new DataGrid();
            _dataGrid.ID = "DataGrid";

            // Create the DataTable.
            DataTable dataTable = new DataTable();

            // Add four column objects to the table.
            DataColumn idColumn = new  DataColumn();
            idColumn.DataType = System.Type.GetType("System.Int32");
            idColumn.ColumnName = "ID";
            idColumn.Caption = "ID";
            idColumn.AutoIncrement = true;
            dataTable.Columns.Add(idColumn);

            DataColumn Product = new DataColumn();
            Product.DataType = System.Type.GetType("System.String");
            Product.ColumnName = "Product";
            Product.Caption = "Product";
            dataTable.Columns.Add(Product);

            DataColumn productCategory = new DataColumn();
            productCategory.DataType = System.Type.GetType("System.String");
            productCategory.ColumnName = "Category";
            productCategory.Caption = "Category";
            dataTable.Columns.Add(productCategory);

            DataColumn Stock = new DataColumn();
            Stock.DataType = System.Type.GetType("System.Int32");
            Stock.ColumnName = "Stock";
            Stock.Caption = "Stock";
            dataTable.Columns.Add(Stock);

            // Once a table has been created, use the NewRow method 
            // to create a DataRow.
            DataRow dataRow;

            // Add first row to collection.
            dataRow = dataTable.NewRow();
            dataRow["Product"] = "Aniseed Syrup";
            dataRow["Category"] = "Condiments";
            dataRow["Stock"] = 25;
            dataTable.Rows.Add(dataRow);

            // Add a second row.
            dataRow = dataTable.NewRow();
            dataRow["Product"] = "Vegie-spread";
            dataRow["Category"] = "Condiments";
            dataRow["Stock"] = 10;
            dataTable.Rows.Add(dataRow);

            //Add a third row.
            dataRow = dataTable.NewRow();
            dataRow["Product"] = "Outback Lager";
            dataRow["Category"] = "Beverages";
            dataRow["Stock"] = 30;
            dataTable.Rows.Add(dataRow);

            // Add a fourth row.
            dataRow = dataTable.NewRow();
            dataRow["Product"] = "Boston Crab Meat";
            dataRow["Category"] = "Seafood";
            dataRow["Stock"] = 10;
            dataTable.Rows.Add(dataRow);

            // Add a fifth row.
            dataRow = dataTable.NewRow();
            dataRow["Product"] = "Tofu";
            dataRow["Category"] = "Produce";
            dataRow["Stock"] = 41;
            dataTable.Rows.Add(dataRow);

            // Set the DataGrid's DataSource.
            _dataGrid.DataSource = dataTable;
            
            // Format the DataGrid.
            _dataGrid.HeaderStyle.Font.Bold = true;
            _dataGrid.HeaderStyle.ForeColor = Color.DarkBlue;
            _dataGrid.HeaderStyle.HorizontalAlign = HorizontalAlign.Center;
            _dataGrid.AlternatingItemStyle.BackColor = Color.Beige;

            _dataGrid.DataBind();
            Controls.Add(_dataGrid);

            // Set the DataTable field names.
            //This information will be passed to the Provider Web Part 
            // when firing the FilterConsumerInit event.
            int columnCount = dataTable.Columns.Count;
            _filterFieldNames = new string[columnCount];
            _filterFieldDisplayNames = new string[columnCount];

            for(int i = 0; i < columnCount; i++)
            {
                _filterFieldNames[i] = dataTable.Columns[i].ColumnName;
                _filterFieldDisplayNames[i] = dataTable.Columns[i].Caption;
            }
        }
    }
}

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