Monday, July 20, 2009


DataTable.Select problem with column name having space

DataTable.Select problem with column name having space

I have a DataTable with a column named “Insurance ID”. I don’t have any control over how I am getting this data. I want to select a particular row but the DataTable.Select method fails because there is a space in the column name.

I have tried:
1) string expr= “Insurance ID = ‘1′”
2)
string expr=“‘Insurance ID‘ = ‘1′”
3)
string expr=“\”Insurance ID\” = ‘1′”


used with the following:

DataRow [] oaDR = myDataTable.Select(expr);

1 and 3 fail with an exception. 2 runs but nothing is found.

After some research I solved the issue using

string expr=”[Insurance ID]=’1′”

DataRow [] dRow = myDataTable.Select(expr);

Friday, July 10, 2009

String Format for DateTime [C#]

String Format for DateTime [C#]

This example shows how to format DateTime using String.Format method. All formatting can be done also using DateTime.ToString method.

Custom DateTime Formatting

There are following custom format specifiers y (year), M (month), d (day), h (hour 12), H (hour 24), m (minute), s (second), f (second fraction), F (second fraction, trailing zeroes are trimmed),t (P.M or A.M) and z (time zone).

Following examples demonstrate how are the format specifiers rewritten to the output.

[C#]
// create date time 2008-03-09 16:05:07.123 DateTime dt = new DateTime(2008, 3, 9, 16, 5, 7, 123);  String.Format("{0:y yy yyy yyyy}", dt);  // "8 08 008 2008"   year String.Format("{0:M MM MMM MMMM}", dt);  // "3 03 Mar March"  month String.Format("{0:d dd ddd dddd}", dt);  // "9 09 Sun Sunday" day String.Format("{0:h hh H HH}",     dt);  // "4 04 16 16"      hour 12/24 String.Format("{0:m mm}",          dt);  // "5 05"            minute String.Format("{0:s ss}",          dt);  // "7 07"            second String.Format("{0:f ff fff ffff}", dt);  // "1 12 123 1230"   sec.fraction String.Format("{0:F FF FFF FFFF}", dt);  // "1 12 123 123"    without zeroes String.Format("{0:t tt}",          dt);  // "P PM"            A.M. or P.M. String.Format("{0:z zz zzz}",      dt);  // "-6 -06 -06:00"   time zone

You can use also date separator / (slash) and time sepatator : (colon). These characters will be rewritten to characters defined in the current DateTimeForma tInfo.DateSepa rator andDateTimeForma tInfo.TimeSepa rator.

[C#]
// date separator in german culture is "." (so "/" changes to ".") String.Format("{0:d/M/yyyy HH:mm:ss}", dt); // "9/3/2008 16:05:07" - english (en-US) String.Format("{0:d/M/yyyy HH:mm:ss}", dt); // "9.3.2008 16:05:07" - german (de-DE)  

Here are some examples of custom date and time formatting:

[C#]
// month/day numbers without/with leading zeroes String.Format("{0:M/d/yyyy}", dt);            // "3/9/2008" String.Format("{0:MM/dd/yyyy}", dt);          // "03/09/2008"  // day/month names String.Format("{0:ddd, MMM d, yyyy}", dt);    // "Sun, Mar 9, 2008" String.Format("{0:dddd, MMMM d, yyyy}", dt);  // "Sunday, March 9, 2008"  // two/four digit year String.Format("{0:MM/dd/yy}", dt);            // "03/09/08" String.Format("{0:MM/dd/yyyy}", dt);          // "03/09/2008" 

Standard DateTime Formatting

In DateTimeForma tInfo there are defined standard patterns for the current culture. For example property ShortTimePattern is string that contains value h:mm tt for en-US culture and value HH:mm for de-DE culture.

Following table shows patterns defined in DateTimeForma tInfo and their values for en-US culture. First column contains format specifiers for the String.Format method.

SpecifierDateTimeFormatInfo propertyPattern value (for en-US culture)
tShortTimePatternh:mm tt
dShortDatePatternM/d/yyyy
TLongTimePatternh:mm:ss tt
DLongDatePatterndddd, MMMM dd, yyyy
f(combination of D and t)dddd, MMMM dd, yyyy h:mm tt
FFullDateTimePatterndddd, MMMM dd, yyyy h:mm:ss tt
g(combination of d and t)M/d/yyyy h:mm tt
G(combination of d and T)M/d/yyyy h:mm:ss tt
m, MMonthDayPatternMMMM dd
y, YYearMonthPatternMMMM, yyyy
r, RRFC1123Patternddd, dd MMM yyyy HH':'mm':'ss 'GMT' (*)
sSortableDateTi mePatternyyyy'-'MM'-'dd'T'HH':'mm':'ss (*)
uUniversalSorta bleDateTimePat ternyyyy'-'MM'-'dd HH':'mm':'ss'Z' (*)
(*) = culture independent
String.Format("{0:t}", dt);  // "4:05 PM"                         ShortTime String.Format("{0:d}", dt);  // "3/9/2008"                        ShortDate String.Format("{0:T}", dt);  // "4:05:07 PM"                      LongTime String.Format("{0:D}", dt);  // "Sunday, March 09, 2008"          LongDate String.Format("{0:f}", dt);  // "Sunday, March 09, 2008 4:05 PM"  LongDate+ShortTime String.Format("{0:F}", dt);  // "Sunday, March 09, 2008 4:05:07 PM" FullDateTime String.Format("{0:g}", dt);  // "3/9/2008 4:05 PM"                ShortDate+ShortTime String.Format("{0:G}", dt);  // "3/9/2008 4:05:07 PM"             ShortDate+LongTime String.Format("{0:m}", dt);  // "March 09"                        MonthDay String.Format("{0:y}", dt);  // "March, 2008"                     YearMonth String.Format("{0:r}", dt);  // "Sun, 09 Mar 2008 16:05:07 GMT"   RFC1123 String.Format("{0:s}", dt);  // "2008-03-09T16:05:07"             SortableDateTime String.Format("{0:u}", dt);  // "2008-03-09 16:05:07Z"            UniversalSortableDateTime 

Thursday, July 9, 2009

WebORB for .NET

WebORB for .NET

WebORB for .NET is a robust, non-intrusive, multi-protocol development and runtime environment that is designed to effortlessly connect Flex, Flash, AJAX and Silverlight clients with .NET objects, XML Web Services, native operating system resources and rich media streams (audio and video). The goal for our products is to enable a new generation of web applications with enhanced UI capabilities, robust client-server communication, streamlined data synchronization, transaction services support and real-time messaging, all at a reasonable cost that delivers fast time to market.

Page Life Cycle

General Page Life-cycle Stages

In general terms, the page goes through the stages outlined in the following table. In addition to the page life-cycle stages, there are application stages that occur before and after a request but are not specific to a page. For more information, see ASP.NET Application Life Cycle Overview for IIS 7.0.

Stage

Description

Page request

The page request occurs before the page life cycle begins. When the page is requested by a user, ASP.NET determines whether the page needs to be parsed and compiled (therefore beginning the life of a page), or whether a cached version of the page can be sent in response without running the page.

Start

In the start step, page properties such as Request and Response are set. At this stage, the page also determines whether the request is a postback or a new request and sets the IsPostBack property. Additionally, during the start step, the page's UICulture property is set.

Page initialization

During page initialization, controls on the page are available and each control's UniqueID property is set. Any themes are also applied to the page. If the current request is a postback, the postback data has not yet been loaded and control property values have not been restored to the values from view state.

Load

During load, if the current request is a postback, control properties are loaded with information recovered from view state and control state.

Validation

During validation, the Validate method of all validator controls is called, which sets the IsValid property of individual validator controls and of the page.

Postback event handling

If the request is a postback, any event handlers are called.

Rendering

Before rendering, view state is saved for the page and all controls. During the rendering phase, the page calls the Render method for each control, providing a text writer that writes its output to the OutputStream of the page's Response property.

Unload

Unload is called after the page has been fully rendered, sent to the client, and is ready to be discarded. At this point, page properties such as Responseand Request are unloaded and any cleanup is performed.

Life-cycle Events

Within each stage of the life cycle of a page, the page raises events that you can handle to run your own code. For control events, you bind the event handler to the event, either declaratively using attributes such as onclick, or in code.

Pages also support automatic event wire-up, meaning that ASP.NET looks for methods with particular names and automatically runs those methods when certain events are raised. If the AutoEventWireup attribute of the @ Page directive is set to true (or if it is not defined, since by default it is true), page events are automatically bound to methods that use the naming convention of Page_event, such as Page_Load and Page_Init. For more information on automatic event wire-up, see ASP.NET Web Server Control Event Model.

The following table lists the page life-cycle events that you will use most frequently. There are more events than those listed; however, they are not used for most page processing scenarios. Instead, they are primarily used by server controls on the ASP.NET Web page to initialize and render themselves. If you want to write your own ASP.NET server controls, you need to understand more about these stages. For information about creating custom controls, see Developing Custom ASP.NET Server Controls.

Page Event

Typical Use

PreInit

Use this event for the following:

  • Check the IsPostBack property to determine whether this is the first time the page is being processed.

  • Create or re-create dynamic controls.

  • Set a master page dynamically.

  • Set the Theme property dynamically.

  • Read or set profile property values.

    NoteNote:
    If the request is a postback, the values of the controls have not yet been restored from view state. If you set a control property at this stage, its value might be overwritten in the next event.

Init

Raised after all controls have been initialized and any skin settings have been applied. Use this event to read or initialize control properties.

InitComplete

Raised by the Page object. Use this event for processing tasks that require all initialization be complete.

PreLoad

Use this event if you need to perform processing on your page or control before the Load event.

Before the Page instance raises this event, it loads view state for itself and all controls, and then processes any postback data included with theRequest instance.

Load

The Page calls the OnLoad event method on the Page, then recursively does the same for each child control, which does the same for each of its child controls until the page and all controls are loaded.

Use the OnLoad event method to set properties in controls and establish database connections.

Control events

Use these events to handle specific control events, such as a Button control's Click event or a TextBox control's TextChanged event.

NoteNote:
In a postback request, if the page contains validator controls, check the IsValid property of the Page and of individual validation controls before performing any processing.

LoadComplete

Use this event for tasks that require that all other controls on the page be loaded.

PreRender

Before this event occurs:

The PreRender event occurs for each control on the page. Use the event to make final changes to the contents of the page or its controls.

SaveStateComplete

Before this event occurs, ViewState has been saved for the page and for all controls. Any changes to the page or controls at this point will be ignored.

Use this event perform tasks that require view state to be saved, but that do not make any changes to controls.

Render

This is not an event; instead, at this stage of processing, the Page object calls this method on each control. All ASP.NET Web server controls have a Render method that writes out the control's markup that is sent to the browser.

If you create a custom control, you typically override this method to output the control's markup. However, if your custom control incorporates only standard ASP.NET Web server controls and no custom markup, you do not need to override the Render method. For more information, seeDeveloping Custom ASP.NET Server Controls.

A user control (an .ascx file) automatically incorporates rendering, so you do not need to explicitly render the control in code.

Unload

This event occurs for each control and then for the page. In controls, use this event to do final cleanup for specific controls, such as closing control-specific database connections.

For the page itself, use this event to do final cleanup work, such as closing open files and database connections, or finishing up logging or other request-specific tasks.

NoteNote:
During the unload stage, the page and its controls have been rendered, so you cannot make further changes to the response stream. If you attempt to call a method such as the Response.Write method, the page will throw an exception.

Additional Page Life Cycle Considerations

Individual ASP.NET server controls have their own life cycle that is similar to the page life cycle. For example, a control's Init and Load events occur during the corresponding page events.

Although both Init and Load recursively occur on each control, they happen in reverse order. The Init event (and also the Unload event) for each child control occur before the corresponding event is raised for its container (bottom-up). However the Load event for a container occurs before the Load events for its child controls (top-down).

You can customize the appearance or content of a control by handling the events for the control, such as the Click event for the Button control and the SelectedIndexChangedevent for the ListBox control. Under some circumstances, you might also handle a control's DataBinding or DataBound events. For more information, see the class reference topics for individual controls and Developing Custom ASP.NET Server Controls.

When inheriting a class from the Page class, in addition to handling events raised by the page, you can override methods from the page's base class. For example, you can override the page's InitializeCulture method to dynamically set culture information. Note that when creating an event handler using the Page_event syntax, the base implementation is implicitly called and therefore you do not need to call it in your method. For example, the base page class's OnLoad method is always called, whether you create a Page_Load method or not. However, if you override the page OnLoad method with the override keyword (Overrides in Visual Basic), you must explicitly call the base method. For example, if you override the OnLoad method on the page, you must call base.Load (MyBase.Load in Visual Basic) in order for the base implementation to be run.

Catch-up Events for Added Controls

If controls are created dynamically at run time or are authored declaratively within templates of data-bound controls, their events are initially not synchronized with those of other controls on the page. For example, for a control that is added at run time, the Init and Load events might occur much later in the page life cycle than the same events for controls created declaratively. Therefore, from the time that they are instantiated, dynamically added controls and controls in templates raise their events one after the other until they have caught up to the event during which it was added to the Controls collection.

In general, you do not need to be concerned about this unless you have nested data-bound controls. If a child control has been data bound, but its container control has not yet been data bound, the data in the child control and the data in its container control can be out of sync. This is true particularly if the data in the child control performs processing based on a data-bound value in the container control.

For example, suppose you have a GridView that displays a company record in each row along with a list of the company officers in a ListBox control. To fill the list of officers, you would bind the ListBox control to a data source control (such as SqlDataSource) that retrieves the company officer data using the CompanyID in a query.

If the ListBox control's data-binding properties, such as DataSourceID and DataMember, are set declaratively, the ListBox control will try to bind to its data source during the containing row's DataBinding event. However, the CompanyID field of the row does not contain a value until the GridView control's RowDataBound event occurs. In this case, the child control (the ListBox control) is bound before the containing control (the GridView control) is bound, so their data-binding stages are out of sync.

To avoid this condition, put the data source control for the ListBox control in the same template item as the ListBox control itself, and do not set the data binding properties of the ListBox declaratively. Instead, set them programmatically at run time during the RowDataBound event, so that the ListBox control does not bind to its data until the CompanyID information is available.