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IWebPartRow.Schema Property

Gets the schema information for a data row that is used to share data between two WebPart controls.

Namespace:  System.Web.UI.WebControls.WebParts
Assembly:  System.Web (in System.Web.dll)

PropertyDescriptorCollection Schema { get; }

This property provides property information for the data. Using the IWebPartRow interface in a connection, you get a PropertyDescriptorCollection object, which is referenced by the Schema property. The contract specifies that calling Schema[n].GetValue(RowData) returns the value of the nth column in the row. You need to use the Schema property to get the values in the row.

The following code example shows the implementation and use of the Schema property. The complete example is shown in the class overview for the IWebPartRow interface. The provider control implements the Schema property. Then the consumer control, in its RenderContents method, queries the Schema property to retrieve information about the row as it writes the row data to the page.

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Reflection;
using System.Security.Permissions;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;

namespace Samples.AspNet.CS.Controls 
{
  // This sample code creates a Web Parts control that acts as a provider  
  // of row data.
  [AspNetHostingPermission(SecurityAction.Demand,
    Level = AspNetHostingPermissionLevel.Minimal)]
  [AspNetHostingPermission(SecurityAction.InheritanceDemand,
    Level = AspNetHostingPermissionLevel.Minimal)]
  public sealed class RowProviderWebPart : WebPart, IWebPartRow 
	{
    private DataTable _table;

    public RowProviderWebPart() 
		{
      _table = new DataTable();

      DataColumn col = new DataColumn();
      col.DataType = typeof(string);
      col.ColumnName = "Name";
      _table.Columns.Add(col);

      col = new DataColumn();
      col.DataType = typeof(string);
      col.ColumnName = "Address";
      _table.Columns.Add(col);

      col = new DataColumn();
      col.DataType = typeof(int);
      col.ColumnName = "ZIP Code";
      _table.Columns.Add(col);

      DataRow row = _table.NewRow();
      row["Name"] = "John Q. Public";
      row["Address"] = "123 Main Street";
      row["ZIP Code"] = 98000;
      _table.Rows.Add(row);
    }

    [ConnectionProvider("Row")]
    public IWebPartRow GetConnectionInterface()
		{
      return new RowProviderWebPart();
    }

    public PropertyDescriptorCollection Schema 
		{
      get 
      {
        return TypeDescriptor.GetProperties(_table.DefaultView[0]);
			}
    }

		public void GetRowData(RowCallback callback)
		{
			callback(_table.Rows);
		}

  } // RowProviderWebPart 


  // This sample code creates a Web Parts control that acts as a consumer  
  // of row data.
  [AspNetHostingPermission(SecurityAction.Demand,
    Level = AspNetHostingPermissionLevel.Minimal)]
  [AspNetHostingPermission(SecurityAction.InheritanceDemand,
    Level = AspNetHostingPermissionLevel.Minimal)]  
  public sealed class RowConsumerWebPart : WebPart 
  {
    private IWebPartRow _provider;
		private ICollection _tableData;
	
		private void GetRowData(object rowData)
		{
			_tableData = (ICollection)rowData;
		}

		protected override void OnPreRender(EventArgs e)
		{
			if (_provider != null)
			{
				_provider.GetRowData(new RowCallback(GetRowData));
			}
		}


    protected override void RenderContents(HtmlTextWriter writer) 
    {
      if (_provider != null) 
      {
        PropertyDescriptorCollection props = _provider.Schema;
		    int count = 0;
        if (props != null && props.Count > 0 && _tableData != null) 
        {
            foreach (PropertyDescriptor prop in props) 
			      {
				      foreach (DataRow o in _tableData)
				      {
					      writer.Write(prop.DisplayName + ": " + o[count]);
					      writer.WriteBreak();
					      writer.WriteLine();
					      count = count + 1;
				      }
            }
        }
        else 
        {
          writer.Write("No data");
        }
      }
      else 
      {
        writer.Write("Not connected");
      }
    }

    [ConnectionConsumer("Row")]
    public void SetConnectionInterface(IWebPartRow provider) 
		{
      _provider = provider;
    }

  } // RowConsumerWebPart

} // Samples.AspNet.CS.Controls 

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0
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