📄 data binding in _net - c# windows forms.htm
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<H1><SPAN lang=de-ch>Data Binding in .NET / C# Windows Forms</SPAN> </H1>
<P><SPAN lang=en-us>More Information on installing the .Net Framework
click <A href="http://www.akadia.com/services/dotnet_dbaccess.html"
target=_top>here</A>.<BR></SPAN><A
href="http://www.akadia.com/download/documents/DataBinding.zip"
target=_top>Download</A> full Visual Studio C# .NET Example from this
Article. </P>
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<H1><SPAN lang=de-ch>Contents</SPAN> </H1>
<BLOCKQUOTE>
<P class=header><A
href="http://www.akadia.com/services/dotnet_databinding.html#Overview">Overview</A>
</P>
<P class=header><SPAN lang=en-us><A
href="http://www.akadia.com/services/dotnet_databinding.html#Binding%20Context">Binding
Context</A></SPAN> </P>
<P class=header><SPAN lang=en-us><A
href="http://www.akadia.com/services/dotnet_databinding.html#CurrencyManager">CurrencyManager</A></SPAN>
</P>
<P class=header><SPAN lang=en-us><A
href="http://www.akadia.com/services/dotnet_databinding.html#Bindable%20Data%20Sources">Bindable
Data Sources</A></SPAN> </P>
<BLOCKQUOTE>
<P><SPAN lang=en-us><A
href="http://www.akadia.com/services/dotnet_databinding.html#Array%20or%20Collection">Array
or Collection</A><BR><A
href="http://www.akadia.com/services/dotnet_databinding.html#ADO.NET%20Data%20Objects">ADO.NET
Data Objects</A></SPAN> </P>
<BLOCKQUOTE>
<P><SPAN lang=en-us><A
href="http://www.akadia.com/services/dotnet_databinding.html#DataColumn">DataColumn</A><B><BR></B><A
href="http://www.akadia.com/services/dotnet_databinding.html#DataTable">DataTable</A><BR><A
href="http://www.akadia.com/services/dotnet_databinding.html#DataView">DataView</A><BR><A
href="http://www.akadia.com/services/dotnet_databinding.html#DataSet">DataSet</A><BR><A
href="http://www.akadia.com/services/dotnet_databinding.html#DataViewManager">DataViewManager</A></SPAN>
</P></BLOCKQUOTE></BLOCKQUOTE>
<P class=header><SPAN lang=en-us><A
href="http://www.akadia.com/services/dotnet_databinding.html#Example:%20Automatically%20synchronized%20Master-Detail">Example:
Automatically synchronized Master-Detail</A></SPAN> </P>
<BLOCKQUOTE>
<P><SPAN lang=de-ch><A
href="http://www.akadia.com/services/dotnet_databinding.html#Managing%20Data%20Relation">Managing
Data Relation</A><BR></SPAN><A
href="http://www.akadia.com/services/dotnet_databinding.html#Binding%20to%20a%20DataGrid">Binding
to a DataGrid</A><BR><SPAN lang=de-ch><A
href="http://www.akadia.com/services/dotnet_databinding.html#Binding%20to%20a%20Combobox">Binding
to a Combobox</A></SPAN> </P></BLOCKQUOTE>
<P class=header><A
href="http://www.akadia.com/services/dotnet_databinding.html#Example:%20Forms%20BindingContext%20Position%20Management"><SPAN
lang=en-us>Example:</SPAN> Form's BindingContext <SPAN
lang=de-ch>Position Management</SPAN></A> </P>
<BLOCKQUOTE>
<P><A
href="http://www.akadia.com/services/dotnet_databinding.html#Handling%20of%20the%20PositionChanged%20event%20for%20the%20Forms%20BindingContext"><SPAN
lang=de-ch>Handling of the</SPAN> PositionChanged event for the Form's
BindingContext</A><BR><SPAN lang=en-us><A
href="http://www.akadia.com/services/dotnet_databinding.html#Format%20and%20Parse%20Events%20of%20the%20Binding%20Class">Format
and Parse Events of the Binding Class</A></SPAN> </P></BLOCKQUOTE>
<P class=header><A
href="http://www.akadia.com/services/dotnet_databinding.html#Example:%20Binding%20to%20a%20ComboBox%20or%20ListBox"><SPAN
lang=de-ch>Example:</SPAN> Binding to a ComboBox or ListBox</A> </P>
<BLOCKQUOTE>
<P><A
href="http://www.akadia.com/services/dotnet_databinding.html#Bind%20a%20ComboBox%20to%20an%20array%20of%20State%20objects"><SPAN
lang=de-ch>B</SPAN>ind a ComboBox to an array of State objects</A>
</P></BLOCKQUOTE></BLOCKQUOTE>
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<H1><A name=Overview>Overview</A> </H1>
<BLOCKQUOTE>
<P>Data binding provides a way for developers to create a read/write
link between the controls on a form and the data in their application
(their data model). Classically, data binding was used within
applications to take advantage of data stored in databases. Windows
Forms data binding allows you to access <B>data from databases</B> as
well as data in other structures, such as <B>arrays</B> and
<B>collections</B><SPAN lang=de-ch>.</SPAN> </P>
<P align=center><IMG height=242
src="Data Binding in _NET - C# Windows Forms_files/dotnet_databinding_1.gif"
width=413 border=0> </P></BLOCKQUOTE>
<H1 align=left><SPAN lang=en-us><A name="Binding Context">Binding
Context</A></SPAN> </H1>
<BLOCKQUOTE>
<P><SPAN lang=en-us>Each Windows Form has at least one
<B>BindingContext</B> object that manages the <B>CurrencyManager</B>
objects for the form. <B>For each data source on a Windows Form, there
is a single CurrencyManager object.</B> Because there may be multiple
data sources associated with a Windows Form, the BindingContext object
enables you to retrieve any particular CurrencyManager object associated
with a data source.</SPAN> </P></BLOCKQUOTE>
<P class=header><SPAN lang=en-us>Example</SPAN> </P>
<BLOCKQUOTE>
<P><SPAN lang=en-us>For example if you add a TextBox control to a form
and bind it to a column of a table (e.g. "Customers.FirstName") in a
dataset (e.g. "dsCust"), <B>the control communicates with the
BindingContext object for that form</B>. The BindingContext object, in
turn, talks to the specific CurrencyManager object for that data
association. If you queried the CurrencyManager's Position property, it
would report the current record for that TextBox control's binding. In
the example below, a TextBox control is bound to the FirstName column of
a Customers table on the</SPAN> <FONT size=2><SPAN
lang=en-us>dsCust</SPAN></FONT> <SPAN lang=en-us>dataset through the
BindingContext object for the form it is on.</SPAN> </P>
<P class=courier align=left><SPAN lang=en-us><FONT color=#0000ff>//
Simple Data Binding</FONT><BR><B>txtBox</B></SPAN><B><SPAN
lang=en-us>.DataBindings.Add("Text",</SPAN><FONT size=2><SPAN
lang=en-us>dsCust</SPAN></FONT><SPAN
lang=en-us>,"Customers.FirstName");</SPAN></B> </P>
<P class=courier align=left><SPAN lang=en-us><FONT color=#0000ff>// Get
current Rowposition</FONT><B><BR></B></SPAN><B><FONT size=2><SPAN
lang=en-us>CurrencyManager cm =
(CurrencyManager)this.BindingContext[dsCust,"Customers"];<BR>long
rowPosition = (long</SPAN></FONT></B><SPAN lang=en-us><FONT
size=2><B>)cm.Position;</B></FONT></SPAN> </P></BLOCKQUOTE>
<H1><SPAN lang=en-us><A name=CurrencyManager>CurrencyManager</A></SPAN>
</H1>
<BLOCKQUOTE>
<P><SPAN lang=en-us>The CurrencyManager is used to <B>keep data-bound
controls synchronized with each other (showing data from the same
record).</B> The CurrencyManager object does this by managing a
collection of the bound data supplied by a data source. For each data
source associated with a Windows Form, the form maintains at least one
CurrencyManager. Because there may be more than one data source
associated with a form, the BindingContext object manages all of the
CurrencyManager objects for any particular form. More broadly, all
container controls have at least one BindingContext object to manage
their CurrencyManagers.</SPAN> </P>
<P><SPAN lang=en-us>An <B>important property</B> of the CurrencyManager
is the <B>Position</B> property. <I>Currency</I> is a term used to refer
to the currentness of position within a data structure. You can use the
Position property of the CurrencyManager class to determine the current
position of all controls bound to the same CurrencyManager.</SPAN> </P>
<P><SPAN lang=en-us>For example, imagine a collection consisting of two
columns called "ContactName" and "Phone". Two TextBox controls are bound
to the same data source. When the Position property of the common
CurrencyManager is set to the fourth position within that list
(corresponding to the fifth name, because it is zero-based), both
controls display the appropriate values (the fifth "ContactName" and the
fifth "Phone") for that position in the data source.</SPAN>
</P></BLOCKQUOTE>
<P class=header><SPAN lang=en-us>Example</SPAN> </P>
<BLOCKQUOTE>
<P><SPAN lang=en-us>For example the Position property of the
CurrencyManager is often manipulated in a Next / Prev Navigation
Button.</SPAN> </P>
<P><IMG height=58
src="Data Binding in _NET - C# Windows Forms_files/dotnet_databinding_2.gif"
width=304 border=0> </P>
<P class=courier><SPAN lang=en-us><FONT color=#0000ff>// Position to
next Record in Customer</FONT><BR>private void btnNext_Click(object
sender, System.EventArgs e)<BR>{<BR></SPAN><B><SPAN
lang=en-us> CurrencyManager cm =
(CurrencyManager)this.BindingContext[dsCust,"Customers"];<BR>
if (cm.Position < cm.Count - 1)<BR>
{<BR>
cm.Position++;<BR> }<BR></SPAN></B><SPAN
lang=en-us>}</SPAN> </P></BLOCKQUOTE>
<H1><SPAN lang=en-us><A name="Bindable Data Sources">Bindable Data
Sources</A></SPAN> </H1>
<BLOCKQUOTE>
<P><SPAN lang=en-us>In Windows Forms, you can bind to a wide variety of
structures, from simple (arrays) to complex (data rows, data views, and
so on). <B>As a minimum, a bindable structure must support the IList
interface</B>. As structures are based on increasingly capable
interfaces, they offer more features that you can take advantage of when
data binding. The list below summarizes the type of structures (data
containers) you can bind to and provides some notes about what
data-binding features are supported.</SPAN> </P></BLOCKQUOTE>
<P class=header><SPAN lang=en-us><A name="Array or Collection">Array or
Collection</A></SPAN> </P>
<BLOCKQUOTE>
<P><SPAN lang=en-us>To act as a data source, a list must implement the
<B>IList</B> interface; one example would be an array that is an
instance of the <I>System.Array</I> class.</SPAN> </P></BLOCKQUOTE>
<P class=header><SPAN lang=en-us><A name="ADO.NET Data Objects">ADO.NET
Data Objects</A></SPAN> </P>
<BLOCKQUOTE>
<P><SPAN lang=en-us>ADO.NET provides a number of data structures
suitable for binding to:</SPAN> </P>
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<LI><SPAN lang=en-us><B><A name=DataColumn>DataColumn</A></B>
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