October 10, 2011 07:21 by Scott
C# 4.0 supports Dynamic Programming by introducing new Dynamic Typed Objects. The type of these objects is resolved at run-time instead of compile-time. A new keyword dynamic is introduced to declare dynamic typed object. The keyword tells the compiler that everything to do with the object, declared as dynamic, should be done dynamically at the run-time using Dynamic Language Runtime(DLR). Remember dynamic keyword is different from var keyword. When we declare an object as var, it is resolved at compile-time whereas in case of dynamic the object type is dynamic and its resolved at run-time. Let’s do some coding to see advantage of Dynamic Typed Objects :)
A year back I wrote a code of setting property of an object using Reflection:
1: Assembly asmLib= Assembly.LoadFile(@"C:\temp\DemoClass\bin\Debug\DemoClass.dll");
2: Type demoClassType = asmLib.GetType("DemoClass.DemoClassLib");
3: object demoClassobj= Activator.CreateInstance(demoClassType);
4: PropertyInfo pInfo= demoClassType.GetProperty("Name");
5: pInfo.SetValue(demoClassobj, "Adil", null);
Notice line 3-5 creates instance of ‘demoClassType’ and set property ‘Name’ to ‘Adil’. Now with C# 4.0 line # 3-5 can be written as simple as:
dynamic dynamicDemoClassObj = Activator.CreateInstance(demoClassType);
dynamicDemoClassObj.Name = "Adil";
Simple isn’t it? Let’s see a slide from Anders Hejlsberg’s session at PDC 2008:
From the above slide, you can call method(s) such as x.ToString(), y.ToLower(), z.Add(1) etc and it will work smoothly :)
This feature is great and provides much flexibility for developers. In this post, we explore the dynamic typed object in C# 4.0. We will explore dynamic in detail and other features as well in the coming posts. Of course there are pros and cons of dynamic programming as well but where C# is going is something like having features of both static languages and dynamic languages.
October 6, 2011 08:39 by Scott
Let say you have an XML file and you want to show the information (data in XML file) in GridView. Here, I am going to show you, how to DataBind asp:GridView to the data contained in an XML document.
A standard XML file will look like below:
<?xml version="1.0" encoding="utf-8" ?>
The entity in this file is a Fruit. Apparently, there are three columns (sub-nodes of Fruit node) named id, name and color. However, you can’t bind the data defined in this standard XML file directly to the GridView.
First you have to transform the XML data into a format understandable to GridView (e.g. tabular or rows collection format). You can transform a standard XML document into various formats (e.g. HTML markups) by using XSLT. XML document transformation to different XML formats using XSLT demonstrates a basic data transformation for an XML document and contains the transformation template definition for XSLT file.
Once you have applied a valid XML data tranformation, you can use XmlDataSource control to make a connection to your XML file and then bind it to GridView directly. Below is the markup code to bind a GridView to an XmlDataSource.
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataSourceID="XmlDataSource1">
<asp:BoundField DataField="name" HeaderText="Fruit Name" />
<asp:BoundField DataField="color" HeaderText="Fruit Color" />
<asp:XmlDataSource ID="XmlDataSource1" runat="server" DataFile="~/XMLFile1.xml" TransformFile="~/XSLTFile1.xslt">
Here, XMLFile1.xml is the actual XML file containg the data you want to bind GridView with and XSLTFile1.xslt is the file containing the desired transformation template.
That's all, I hope you have got an idea of
1. How to bind gridview to xml data
2. How to bind gridview to xml file
3. Binding gridview to xmldocument
4. How to modify XML file in order to make it appropriate for GridView DataSource