This article introduces several data binding methods in. net. I use the <% # And %> delimiters most of the time. If you need the Eval and Bind functions, check them out.
The data binding expression is included in the <% # And %> delimiters and uses the Eval and Bind functions. The Eval function is used to define one-way (read-only) binding. The Bind function is used to define bidirectional (updatable) binding. In addition to calling the Eval and Bind methods in the data binding expression to perform data binding, you can also call any common code within the <% # And %> delimiters, to execute the code During page processing and return a value.
When the DataBind method of the control or Page class is called, the data binding expression is parsed. Some controls, such as the GridView, DetailsView, and FormView controls, automatically parse the data binding expression during the PreRender event of the control, and do not need to explicitly call the DataBind Method
There are two types of data binding in ASP. NET: Single-value binding and multi-value binding.
What they have in common: they do not need to work with ADO. NET at the same time.
Differences: Single-value binding can dynamically insert a variable, attribute, or expression into a page to help create a data control template.
Multi-value binding can display the content used by a table. It must support its special control (including the DataSource attribute)
Single value binding:
There are four common expressions:
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| <% = XX %>, inline mode, can reference C # code <Asp: FormView ID = "FormView1" Performanceid = "sqlperformance1" DataKeyNames = "ProductID" RunAt = "server"> <ItemTemplate> <Table> <Tr> <td align = right> <B> Product ID: </B> </td> <% # Eval ("ProductID ") %> </td> </tr> <Tr> <td align = right> <B> Product Name: </B> </td> <% # Eval ("ProductName ") %> </td> </tr> <Tr> <td align = right> <B> Category ID: </B> </td> <% # Eval ("CategoryID ") %> </td> </tr> <Tr> <td align = right> <B> Quantity Per Unit: </B> </td> <% # Eval ("QuantityPerUnit ") %> </td> </tr> <Tr> <td align = right> <B> Unit Price: </B> </td> <% # Eval ("UnitPrice ") %> </td> </tr> </Table> </ItemTemplate> </Asp: FormView> |
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<% # XXX %>, referencing the code field in the. cs File
I have added the extension method version. I like the concept of expansion.
Now, you only need to add a static help class and name it as you like.
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Public static class Helper Public static object Eval <T> (this Page, Func <T, object> func) |
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On the page, you can
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| <% # This. Eval <Student> (_ => _. Name + "(" + _. Age + ")") %> | |
<% # Eval (xxx) %>. You need to bind the data source.
The Eval method can calculate the post-bound data expression in the template of a data binding control (such as the GridView, DetailsView, and FormView controls. At runtime, the Eval method calls the Eval method of the DataBinder object and references the current data item of the named container. A naming container is usually the smallest component of a data binding control that contains a complete record, such as a row in the GridView control. Therefore, the Eval method can only be used for binding to the template of the data binding control.
The following controls are list controls that support data binding:
Asp: RadioButtonList
Asp: CheckBoxList
Asp: DropDownList
Asp: Listbox
The optional items in each of the preceding controls are usually defined in one or more asp: ListItem controls, similar to the following:
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<Html> <Form runat = "server"> </Body> |
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