Difference between Eval and Bind - Data Binding Expressions in ASP.NET

In simple words, the Eval function is used to define one-way binding (read only). The Bind function is used for two-way binding (read-write)

So in a control like the GridView or the FormView, when you have to display read only data using a label control, you would be using the Eval function whereas when you want to update a database field, you would be using a TextBox and thus using the Bind function.

Note: You can use the Bind function to retrieve the value of a databound field, just as Eval does.

Here’s an example:

<asp:FormView ID="FormView1" runat="server"
AllowPaging="True"
DataKeyNames="CustomerID"
DataSourceID="SqlDataSource1">
<
EditItemTemplate>
CustomerName:
<asp:TextBox ID="txtCustName"
runat="server"
Text='<%# Bind("CName") %>'>
</
asp:TextBox>
</
EditItemTemplate>

<
ItemTemplate>
CustID:
<asp:Label ID="lblCustID"
runat="server"
Text='<%# Eval("CID") %>'>
</
asp:Label>
</
ItemTemplate>
</
asp:FormView>
You can read more on the Eval and Bind functions

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About The Author

Suprotim Agarwal
Suprotim Agarwal, Developer Technologies MVP (Microsoft Most Valuable Professional) is the founder and contributor for DevCurry, DotNetCurry and SQLServerCurry. He is the Chief Editor of a Developer Magazine called DNC Magazine. He has also authored two Books - 51 Recipes using jQuery with ASP.NET Controls. and The Absolutely Awesome jQuery CookBook.

Follow him on twitter @suprotimagarwal.

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