Export (0) Print
Expand All

DataSourceDesigner Class

Provides design-time support in a design host for the DataSourceControl class.

Namespace:  System.Web.UI.Design
Assembly:  System.Design (in System.Design.dll)

[SecurityPermissionAttribute(SecurityAction.Demand, Flags = SecurityPermissionFlag.UnmanagedCode)]
public class DataSourceDesigner : ControlDesigner, 
	IDataSourceDesigner

The DataSourceDesigner class is the base class for data source designers, such as the SqlDataSourceDesigner, AccessDataSourceDesigner, and ObjectDataSourceDesigner classes. If you create a new data source control, you might also want to create a custom control designer for your control and derive it from the DataSourceDesigner class.

The DataSourceDesigner class has two event methods: the OnDataSourceChanged and OnSchemaRefreshed methods. Both of these events can be temporarily disabled with the SuppressDataSourceEvents method, which sets the SuppressingDataSourceEvents property. The event methods can be enabled again with the ResumeDataSourceEvents method.

There are two static methods that you can use to evaluate the equivalency of schemas or views without creating an instance of the class:

Notes to Inheritors:

To provide commands for the action list menu at design time in a derived class, you must override the ActionLists property to return a custom DesignerActionListCollection object with custom items that are derived from the DesignerActionList object.

The following code example shows how to use a custom data source control with several other small custom classes, as listed in the following table.

Custom class

Derived from

CustomDataSource

ObjectDataSource

CustomDataSourceDesigner

DataSourceDesigner

CustomDataSourceView

ObjectDataSourceView

CustomDesignDataSourceView

DesignerDataSourceView

BookListViewSchema

IDataSourceViewSchema

CustomIDFieldSchema

IDataSourceFieldSchema

CustomTitleFieldSchema

IDataSourceFieldSchema

BookItem (A two-field data structure.)

After compiling the code example, open the .aspx page in Design view and then set the DataSourceID property to the ID of the custom data source control.

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

namespace ASPNet.Design.Samples_CS
{
    [Designer(typeof(CustomDataSourceDesigner)),
        ToolboxData("<{0}:CustomDataSource runat=\"server\"></{0}:CustomDataSource>")]
    public class CustomDataSource : ObjectDataSource
    {
        private ObjectDataSourceView _view = null;
        private string _defaultViewName = "BookList";

        public CustomDataSource() : base() { }

        // Gets a view by name
        protected override DataSourceView GetView(string viewName)
        {
            // This data source only allows one view
            if (viewName != _defaultViewName)
                return null;
            else if (_view == null)
            {
                _view = new CustomDataSourceView(this, 
                    _defaultViewName, HttpContext.Current);
            }

            return _view;
        }

        // Gets a list of view names for this class
        protected override ICollection GetViewNames()
        {
            ArrayList ar = new ArrayList(1);
            ar.Add(_defaultViewName);
            return ar as ICollection;
        }

    }

    // The runtime data source view
    public class CustomDataSourceView : ObjectDataSourceView
    {
        private ArrayList _data = null;

        public CustomDataSourceView(CustomDataSource owner, 
            string viewName, HttpContext context)
            : base(owner, viewName, context)
        {
            owner.SelectCountMethod = "GetCount";
        }

        // This method would typically get a set of live data  
        // rather than create some dummy data
        protected override IEnumerable ExecuteSelect(
            DataSourceSelectArguments arguments)
        {
            if (_data == null)
            {
                // Create a set of runtime fake data
                _data = new ArrayList();
                _data.Add(new BookItem("ID_1", "Runtime Title 01"));
                _data.Add(new BookItem("ID_2", "Runtime Title 02"));
                _data.Add(new BookItem("ID_3", "Runtime Title 03"));
            }

            return _data as IEnumerable;
        }

        // Allow getting the record count
        public override bool CanRetrieveTotalRowCount
        {
            get { return true; }
        }

        // Returns the number of records in the current set of data
        public int GetCount()
        {
            if (_data == null)
                return 0;
            else
                return _data.Count;
        }

        // Do not allow deletions
        public override bool CanDelete
        {
            get { return false; }
        }
        // Do not allow insertions
        public override bool CanInsert
        {
            get { return false; }
        }
        // Do not allow paging
        public override bool CanPage
        {
            get { return false; }
        }
        // Do not allow sorting
        public override bool CanSort
        {
            get { return false; }
        }
        // Do not allow updating
        public override bool CanUpdate
        {
            get { return false; }
        }

    }

    // A class to define each record of the data
    public class BookItem
    {
        private string _id;
        private string _title;

        public BookItem(string id, string title)
        {
            _id = id;
            _title = title;
        }

        public string ID
        {
            get { return _id; }
        }
        public string Title
        {
            get { return _title; }
            set { _title = value; }
        }
    }

    // Custom designer for the CustomDataSource control.
    public class CustomDataSourceDesigner : DataSourceDesigner
    {
        private CustomDataSource _control;
        private string _defaultViewName = "BookList";
        private CustomDesignDataSourceView _view = null;

        // Initialize the designer
        public override void Initialize(IComponent component)
        {
            base.Initialize(component);
            _control = (CustomDataSource)Component;
        }

        // Get a view
        public override DesignerDataSourceView GetView(string viewName)
        {
            if (!viewName.Equals(_defaultViewName))
                return null;

            if (_view == null)
            {
                _view = new CustomDesignDataSourceView(this,
                    _defaultViewName);
            }

            return _view;
        }

        // Get a list of view names
        public override string[] GetViewNames()
        {
            return new string[] { "BookList" };
        }

        // Do not allow refreshing the schema
        public override bool CanRefreshSchema
        {
            get { return false; }
        }
        // Do not allow resizing
        public override bool AllowResize
        {
            get { return false; }
        }
    }

    // A design-time data source view
    public class CustomDesignDataSourceView : DesignerDataSourceView
    {
        private ArrayList _data = null;

        public CustomDesignDataSourceView(
            CustomDataSourceDesigner owner, string viewName)
            : base(owner, viewName)
        {}

        // Get data for design-time display
        public override IEnumerable GetDesignTimeData(
            int minimumRows, out bool isSampleData)
        {
            if (_data == null)
            {
                // Create a set of design-time fake data
                _data = new ArrayList();
                for (int i = 1; i <= minimumRows; i++)
                {
                    _data.Add(new BookItem("ID_" + i.ToString(),
                        "Design-Time Title 0" + i.ToString()));
                }
            }
            isSampleData = true;
            return _data as IEnumerable;
        }

        public override IDataSourceViewSchema Schema
        {
            get { return new BookListViewSchema(); }
        }

        // Allow getting the record count
        public override bool CanRetrieveTotalRowCount
        {
            get { return true; }
        }
        // Do not allow deletions
        public override bool CanDelete
        {
            get { return false; }
        }
        // Do not allow insertions
        public override bool CanInsert
        {
            get { return false; }
        }
        // Do not allow updates
        public override bool CanUpdate
        {
            get { return false; }
        }
        // Do not allow paging
        public override bool CanPage
        {
            get { return false; }
        }
        // Do not allow sorting
        public override bool CanSort
        {
            get { return false; }
        }
    }

    // A custom View Schema class
    public class BookListViewSchema : IDataSourceViewSchema
    {
        public BookListViewSchema()
        { }

        // The name of this View Schema
        public string Name
        {
            get { return "BookList"; }
        }

        // Build a Field Schema array
        public IDataSourceFieldSchema[] GetFields()
        {
            IDataSourceFieldSchema[] fields = new IDataSourceFieldSchema[2];
            fields[0] = new CustomIDFieldSchema();
            fields[1] = new CustomTitleFieldSchema();
            return fields;
        }
        // There are no child views, so return null
        public IDataSourceViewSchema[] GetChildren()
        {
            return null;
        }
    }

    // A custom Field Schema class for ID
    public class CustomIDFieldSchema : IDataSourceFieldSchema
    {
        public CustomIDFieldSchema()
        { }

        // Name is ID
        public string Name
        {
            get { return "ID"; }
        }
        // Data type is string
        public Type DataType
        {
            get { return typeof(string); }
        }
        // This is not an Identity field
        public bool Identity
        {
            get { return false; }
        }
        // This field is read only
        public bool IsReadOnly
        {
            get { return true; }
        }
        // This field is unique
        public bool IsUnique
        {
            get { return true; }
        }
        // This field can't be longer than 20
        public int Length
        {
            get { return 20; }
        }
        // This field can't be null
        public bool Nullable
        {
            get { return false; }
        }
        // This is a Primary Key
        public bool PrimaryKey
        {
            get { return true; }
        }

        // These properties do not apply
        public int Precision
        {
            get { return -1; }
        }
        public int Scale
        {
            get { return -1; }
        }
    }

    // A custom Field Schema class for Title
    public class CustomTitleFieldSchema : IDataSourceFieldSchema
    {
        public CustomTitleFieldSchema()
        { }

        // Name is Title
        public string Name
        {
            get { return "Title"; }
        }
        // Type is string
        public Type DataType
        {
            get { return typeof(string); }
        }
        // This is not an Identity field
        public bool Identity
        {
            get { return false; }
        }
        // This field is not read only
        public bool IsReadOnly
        {
            get { return false; }
        }
        // This field is not unique
        public bool IsUnique
        {
            get { return false; }
        }
        // This field can't be longer than 100
        public int Length
        {
            get { return 100; }
        }
        // This field can't be null
        public bool Nullable
        {
            get { return false; }
        }
        // This is not the Primary Key
        public bool PrimaryKey
        {
            get { return false; }
        }

        // These properties do not apply
        public int Precision
        {
            get { return -1; }
        }
        public int Scale
        {
            get { return -1; }
        }
    }
}


...


<%@ Page Language="C#" %>
<%@ Register TagPrefix="aspSample" Namespace="ASPNet.Design.Samples_CS" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>

    <aspSample:CustomDataSource ID="CustomDS1" 
        runat="server"></aspSample:CustomDataSource>
    <asp:GridView ID="GridView1" runat="server"></asp:GridView>

    </div>
    </form>
</body>
</html>

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

Community Additions

ADD
Show:
© 2014 Microsoft