- •Table of Contents
- •Preface
- •What is ASP.NET?
- •Installing the Required Software
- •Installing the Web Server
- •Installing Internet Information Services (IIS)
- •Installing Cassini
- •Installing the .NET Framework and the SDK
- •Installing the .NET Framework
- •Installing the SDK
- •Configuring the Web Server
- •Configuring IIS
- •Configuring Cassini
- •Where do I Put my Files?
- •Using localhost
- •Virtual Directories
- •Using Cassini
- •Installing SQL Server 2005 Express Edition
- •Installing SQL Server Management Studio Express
- •Installing Visual Web Developer 2005
- •Writing your First ASP.NET Page
- •Getting Help
- •Summary
- •ASP.NET Basics
- •ASP.NET Page Structure
- •Directives
- •Code Declaration Blocks
- •Comments in VB and C# Code
- •Code Render Blocks
- •ASP.NET Server Controls
- •Server-side Comments
- •Literal Text and HTML Tags
- •View State
- •Working with Directives
- •ASP.NET Languages
- •Visual Basic
- •Summary
- •VB and C# Programming Basics
- •Programming Basics
- •Control Events and Subroutines
- •Page Events
- •Variables and Variable Declaration
- •Arrays
- •Functions
- •Operators
- •Breaking Long Lines of Code
- •Conditional Logic
- •Loops
- •Object Oriented Programming Concepts
- •Objects and Classes
- •Properties
- •Methods
- •Classes
- •Constructors
- •Scope
- •Events
- •Understanding Inheritance
- •Objects In .NET
- •Namespaces
- •Using Code-behind Files
- •Summary
- •Constructing ASP.NET Web Pages
- •Web Forms
- •HTML Server Controls
- •Using the HTML Server Controls
- •Web Server Controls
- •Standard Web Server Controls
- •Label
- •Literal
- •TextBox
- •HiddenField
- •Button
- •ImageButton
- •LinkButton
- •HyperLink
- •CheckBox
- •RadioButton
- •Image
- •ImageMap
- •PlaceHolder
- •Panel
- •List Controls
- •DropDownList
- •ListBox
- •RadioButtonList
- •CheckBoxList
- •BulletedList
- •Advanced Controls
- •Calendar
- •AdRotator
- •TreeView
- •SiteMapPath
- •Menu
- •MultiView
- •Wizard
- •FileUpload
- •Web User Controls
- •Creating a Web User Control
- •Using the Web User Control
- •Master Pages
- •Using Cascading Style Sheets (CSS)
- •Types of Styles and Style Sheets
- •Style Properties
- •The CssClass Property
- •Summary
- •Building Web Applications
- •Introducing the Dorknozzle Project
- •Using Visual Web Developer
- •Meeting the Features
- •The Solution Explorer
- •The Web Forms Designer
- •The Code Editor
- •IntelliSense
- •The Toolbox
- •The Properties Window
- •Executing your Project
- •Using Visual Web Developer’s Built-in Web Server
- •Using IIS
- •Using IIS with Visual Web Developer
- •Core Web Application Features
- •Web.config
- •Global.asax
- •Using Application State
- •Working with User Sessions
- •Using the Cache Object
- •Using Cookies
- •Starting the Dorknozzle Project
- •Preparing the Sitemap
- •Using Themes, Skins, and Styles
- •Creating a New Theme Folder
- •Creating a New Style Sheet
- •Styling Web Server Controls
- •Adding a Skin
- •Applying the Theme
- •Building the Master Page
- •Using the Master Page
- •Extending Dorknozzle
- •Debugging and Error Handling
- •Debugging with Visual Web Developer
- •Other Kinds of Errors
- •Custom Errors
- •Handling Exceptions Locally
- •Summary
- •Using the Validation Controls
- •Enforcing Validation on the Server
- •Using Validation Controls
- •RequiredFieldValidator
- •CompareValidator
- •RangeValidator
- •ValidationSummary
- •RegularExpressionValidator
- •Some Useful Regular Expressions
- •CustomValidator
- •Validation Groups
- •Updating Dorknozzle
- •Summary
- •What is a Database?
- •Creating your First Database
- •Creating a New Database Using Visual Web Developer
- •Creating Database Tables
- •Data Types
- •Column Properties
- •Primary Keys
- •Creating the Employees Table
- •Creating the Remaining Tables
- •Executing SQL Scripts
- •Populating the Data Tables
- •Relational Database Design Concepts
- •Foreign Keys
- •Using Database Diagrams
- •Diagrams and Table Relationships
- •One-to-one Relationships
- •One-to-many Relationships
- •Many-to-many Relationships
- •Summary
- •Speaking SQL
- •Reading Data from a Single Table
- •Using the SELECT Statement
- •Selecting Certain Fields
- •Selecting Unique Data with DISTINCT
- •Row Filtering with WHERE
- •Selecting Ranges of Values with BETWEEN
- •Matching Patterns with LIKE
- •Using the IN Operator
- •Sorting Results Using ORDER BY
- •Limiting the Number of Results with TOP
- •Reading Data from Multiple Tables
- •Subqueries
- •Table Joins
- •Expressions and Operators
- •Transact-SQL Functions
- •Arithmetic Functions
- •String Functions
- •Date and Time Functions
- •Working with Groups of Values
- •The COUNT Function
- •Grouping Records Using GROUP BY
- •Filtering Groups Using HAVING
- •The SUM, AVG, MIN, and MAX Functions
- •Updating Existing Data
- •The INSERT Statement
- •The UPDATE Statement
- •The DELETE Statement
- •Stored Procedures
- •Summary
- •Introducing ADO.NET
- •Importing the SqlClient Namespace
- •Defining the Database Connection
- •Preparing the Command
- •Executing the Command
- •Setting up Database Authentication
- •Reading the Data
- •Using Parameters with Queries
- •Bulletproofing Data Access Code
- •Using the Repeater Control
- •More Data Binding
- •Inserting Records
- •Updating Records
- •Deleting Records
- •Using Stored Procedures
- •Summary
- •DataList Basics
- •Handling DataList Events
- •Editing DataList Items and Using Templates
- •DataList and Visual Web Developer
- •Styling the DataList
- •Summary
- •Using the GridView Control
- •Customizing the GridView Columns
- •Styling the GridView with Templates, Skins, and CSS
- •Selecting Grid Records
- •Using the DetailsView Control
- •Styling the DetailsView
- •GridView and DetailsView Events
- •Entering Edit Mode
- •Using Templates
- •Updating DetailsView Records
- •Summary
- •Advanced Data Access
- •Using Data Source Controls
- •Binding the GridView to a SqlDataSource
- •Binding the DetailsView to a SqlDataSource
- •Displaying Lists in DetailsView
- •More on SqlDataSource
- •Working with Data Sets and Data Tables
- •What is a Data Set Made From?
- •Binding DataSets to Controls
- •Implementing Paging
- •Storing Data Sets in View State
- •Implementing Sorting
- •Filtering Data
- •Updating a Database from a Modified DataSet
- •Summary
- •Security and User Authentication
- •Basic Security Guidelines
- •Securing ASP.NET 2.0 Applications
- •Working with Forms Authentication
- •Authenticating Users
- •Working with Hard-coded User Accounts
- •Configuring Forms Authentication
- •Configuring Forms Authorization
- •Storing Users in Web.config
- •Hashing Passwords
- •Logging Users Out
- •ASP.NET 2.0 Memberships and Roles
- •Creating the Membership Data Structures
- •Using your Database to Store Membership Data
- •Using the ASP.NET Web Site Configuration Tool
- •Creating Users and Roles
- •Changing Password Strength Requirements
- •Securing your Web Application
- •Using the ASP.NET Login Controls
- •Authenticating Users
- •Customizing User Display
- •Summary
- •Working with Files and Email
- •Writing and Reading Text Files
- •Setting Up Security
- •Writing Content to a Text File
- •Reading Content from a Text File
- •Accessing Directories and Directory Information
- •Working with Directory and File Paths
- •Uploading Files
- •Sending Email with ASP.NET
- •Configuring the SMTP Server
- •Sending a Test Email
- •Creating the Company Newsletter Page
- •Summary
- •The WebControl Class
- •Properties
- •Methods
- •Standard Web Controls
- •AdRotator
- •Properties
- •Events
- •BulletedList
- •Properties
- •Events
- •Button
- •Properties
- •Events
- •Calendar
- •Properties
- •Events
- •CheckBox
- •Properties
- •Events
- •CheckBoxList
- •Properties
- •Events
- •DropDownList
- •Properties
- •Events
- •FileUpload
- •Properties
- •Methods
- •HiddenField
- •Properties
- •HyperLink
- •Properties
- •Image
- •Properties
- •ImageButton
- •Properties
- •Events
- •ImageMap
- •Properties
- •Events
- •Label
- •Properties
- •LinkButton
- •Properties
- •Events
- •ListBox
- •Properties
- •Events
- •Literal
- •Properties
- •MultiView
- •Properties
- •Methods
- •Events
- •Panel
- •Properties
- •PlaceHolder
- •Properties
- •RadioButton
- •Properties
- •Events
- •RadioButtonList
- •Properties
- •Events
- •TextBox
- •Properties
- •Events
- •Properties
- •Validation Controls
- •CompareValidator
- •Properties
- •Methods
- •CustomValidator
- •Methods
- •Events
- •RangeValidator
- •Properties
- •Methods
- •RegularExpressionValidator
- •Properties
- •Methods
- •RequiredFieldValidator
- •Properties
- •Methods
- •ValidationSummary
- •Properties
- •Navigation Web Controls
- •SiteMapPath
- •Properties
- •Methods
- •Events
- •Menu
- •Properties
- •Methods
- •Events
- •TreeView
- •Properties
- •Methods
- •Events
- •HTML Server Controls
- •HtmlAnchor Control
- •Properties
- •Events
- •HtmlButton Control
- •Properties
- •Events
- •HtmlForm Control
- •Properties
- •HtmlGeneric Control
- •Properties
- •HtmlImage Control
- •Properties
- •HtmlInputButton Control
- •Properties
- •Events
- •HtmlInputCheckBox Control
- •Properties
- •Events
- •HtmlInputFile Control
- •Properties
- •HtmlInputHidden Control
- •Properties
- •HtmlInputImage Control
- •Properties
- •Events
- •HtmlInputRadioButton Control
- •Properties
- •Events
- •HtmlInputText Control
- •Properties
- •Events
- •HtmlSelect Control
- •Properties
- •Events
- •HtmlTable Control
- •Properties
- •HtmlTableCell Control
- •Properties
- •HtmlTableRow Control
- •Properties
- •HtmlTextArea Control
- •Properties
- •Events
- •Index
Chapter 14: Working with Files and Email
Writing Content to a Text File
For the purposes of the next few exercises, let’s work again with our old friend, the Learning web application. Start Visual Web Developer, go to File > Open Web Site, and open the Learning application.
Right-click the project in Solution Explorer, and select Add New Item. Select the
Web Form template, name it WriteFile.aspx, and make sure you aren’t using a code-behind file or a master page. Click Add, then enter the code shown here in bold:
File: WriteFile.aspx (excerpt)
<%@ Page Language="VB" %>
<%@ Import Namespace="System.IO" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server"> </script>
<html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server">
<title>Writing to Text Files</title> </head>
<body>
<form id="form1" runat="server">
Write the following text within a text file:<br /> <asp:TextBox ID="myText" runat="server" />
<asp:Button ID="writeButton" Text="Write" runat="server" OnClick="WriteText" />
</form>
</body>
</html>
As you can see, we import the System.IO namespace—the namespace that contains the classes for working with text files—first. Next, we add a TextBox control to handle collection of the user-entered text, and a Button control to send the information to the server for processing.
Next, in the <head> tag, we’ll create the WriteText method mentioned in the OnClick attribute of the Button. This method will write the contents of the TextBox to the text file:
576
Writing Content to a Text File
Visual Basic |
File: WriteFile.aspx (excerpt) |
<script runat="server">
Sub WriteText(ByVal s As Object, ByVal e As EventArgs) Using streamWriter As StreamWriter = File.CreateText( _
"C:\WebDocs\Learning\myText.txt")
streamWriter.WriteLine(myText.Text) End Using
End Sub </script>
C# |
File: WriteFile.aspx (excerpt) |
<script runat="server">
void WriteText(Object s, EventArgs e)
{
using (StreamWriter streamWriter = File.CreateText( @"C:\WebDocs\Learning\myText.txt"))
{
streamWriter.WriteLine(myText.Text);
}
}
</script>
Apart from the new Using construct, the code is pretty straightforward. First, we create a StreamWriter variable called streamWriter. To obtain the variable’s value, we call the CreateText method of the File class, passing in the location of the text file, which returns a new StreamWriter. Don’t forget that C# needs to escape backslashes when they’re used in strings, so the path to our file must use \\ to separate folder names, or use the @ character in front of the string so that backslashes are automatically ignored.
What about Using, then? Similarly to database connections, streams are something that we need to close when we’re done working with them, so they don’t occupy resources unnecessarily. The Using construct is a common means of ensuring that the stream is closed and disposed of after we work with it.
Disposing of Objects
Technically, when we work with Using, the object is disposed of, rather than simply closed. The action is identical to explicitly calling its Dispose method.
When the code enclosed by Using finishes executing, streamWriter’s Dispose method is called automatically for you. This ensures that it doesn't keep any resources locked, and that the object itself is removed from memory immediately.
577
Chapter 14: Working with Files and Email
In the world of .NET, closed objects are cleared from memory at regular intervals by .NET’s Garbage Collector, but for classes that support the Dispose method (such as StreamWriter), you can use this method (or the Using construct) to remove an object from memory immediately.
It’s also interesting to note the way we used the File class’s CreateText method in the code above. Normally, when we need to call a method of a particular class, we create an object of that class first. How was it possible to call the CreateText method using a class name, without creating an object of the File class first?
The CreateText method is what Visual Basic calls a shared method, and what’s known in C# as a static method. Shared or static methods can be called without our having to create an actual instance of the class. In the above code, CreateText is a shared or static method, because we can call it directly from the File class, without having to create an instance of that class.
We worked with shared/static class members earlier, when we read the connection string. In that case, you didn’t need to create an object of the ConfigurationManager class in order to read your connection string:
Visual Basic
string connectionString = ConfigurationManager.ConnectionStrings( _ "Dorknozzle").ConnectionString
Instance methods, on the other hand, are those with which you’re familiar—they may only be called on an instance (object) of the class. Instance methods are most commonly used, but shared/static methods can be useful for providing generic functionality that doesn’t need to be tied to a particular class instance.
Now, test the page in your browser. Initially, all you’ll see is an interface similar to Figure 14.4.
Type some text into the text box, and click the Write button to submit your text for processing. Browse to and open the myText.txt file in Notepad, and as in Figure 14.5, you’ll see the newly added text.
If you try to enter a different value into the TextBox control and click the Write button, the existing text will be overwritten with the new content. To prevent this from happening, you can replace the call to the CreateText method with a call to AppendText. As Figure 14.6 shows, the AppendText method adds to existing text, rather than replacing it.
578
Writing Content to a Text File
Figure 14.4. Writing text to a file
Figure 14.5. Viewing your new file in Notepad
Figure 14.6. Appending text
Also note that, rather than specifying the full path to the text file, you can use the MapPath method to generate the full path to the text file automatically. All you need to do is give the method a path relative to the current directory, as follows:
Visual Basic |
File: WriteFile.aspx (excerpt) |
Using streamWriter As StreamWriter = File.AppendText( _ MapPath("myText.txt"))
579