ASP.NET 4 Unleased - p 82 docx

public void UpdateMovieint id, string title, string director, DateTime ➥dateReleased { // Create Command SqlConnection con = new SqlConnection_conString; SqlCommand cmd = new SqlCommand;

Trang 1

public void UpdateMovie(int id, string title, string director, DateTime

➥dateReleased)

{

// Create Command

SqlConnection con = new SqlConnection(_conString);

SqlCommand cmd = new SqlCommand();

cmd.Connection = con;

cmd.CommandText = “UPDATE Movies SET

Title=@Title,Director=@Director,DateReleased=

// Add parameters

cmd.Parameters.AddWithValue(“@Title”, title);

cmd.Parameters.AddWithValue(“@Director”, director);

cmd.Parameters.AddWithValue(“@DateReleased”, dateReleased);

cmd.Parameters.AddWithValue(“@Id”, id);

// Execute command

using (con)

{

con.Open();

cmd.ExecuteNonQuery();

}

public SqlDataReader GetMovies()

{

// Create Connection

// Create Command

cmd.CommandText = “SELECT Id,Title,Director,DateReleased FROM Movies”;

// Return DataReader

con.Open();

return cmd.ExecuteReader(CommandBehavior.CloseConnection);

}

public Movies()

{

_conString =

WebConfigurationManager.ConnectionStrings[“Movies”].ConnectionString;

}

Trang 2

The page in Listing 18.12 contains a GridView and ObjectDataSource control The

ObjectDataSource control includes an UpdateMethod property that points to the

UpdateMovie() method

LISTING 18.12 ShowMovies.aspx

<%@ Page Language=”C#” %>

<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.1//EN”

“http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd”>

<title>Show Movies</title>

</head>

<body>

<div>

<asp:GridView

id=”grdMovies”

DataSourceID=”srcMovies”

DataKeyNames=”Id”

AutoGenerateEditButton=”true”

Runat=”server” />

<asp:ObjectDataSource

id=”srcMovies”

TypeName=”Movies”

SelectMethod=”GetMovies”

UpdateMethod=”UpdateMovie”

Runat=”server”/>

</div>

</form>

</body>

</html>

In Listing 18.12, the GridView automatically adds the update parameters to the

ObjectDataSource control’s UpdateParameters collection As an alternative, you can

declare the parameters used by the ObjectDataSource control explicitly For example, the

page in Listing 18.13 declares all the parameters passed to the UpdateMovie() method

LISTING 18.13 ExplicitShowMovies.aspx

Trang 3

<title>Show Movies</title>

</head>

<body>

<div>

<asp:GridView

id=”grdMovies”

AutoGenerateEditButton=”true”

id=”srcMovies”

TypeName=”Movies”

UpdateMethod=”UpdateMovie”

Runat=”server”>

<asp:Parameter Name=”title” />

<asp:Parameter Name=”director” />

<asp:Parameter Name=”dateReleased” Type=”DateTime” />

<asp:Parameter Name=”id” Type=”Int32” />

</UpdateParameters>

</asp:ObjectDataSource>

</div>

</form>

</body>

</html>

The ObjectDataSource uses reflection to match its parameters against the parameters of

the method that it calls The order of the parameters does not matter, and the case of the

parameters does not matter However, the one thing that does matter is the names of the

parameters

You specify the type of a parameter with the Type property, which represents a member of

the TypeCode enumeration The TypeCode enumeration represents an enumeration of

common NET Framework data types such as Int32, Decimal, and DateTime If the

enumeration does not include a data type that you need, you can use the

TypeCode.Object member from the enumeration

Trang 4

Using Different Parameter Types

You can use all the same types of parameters with the ObjectDataSource control that you

can use with the SqlDataSource control:

Parameter—Represents an arbitrary static value

ControlParameter—Represents the value of a control or page property

CookieParameter—Represents the value of a browser cookie

FormParameter—Represents the value of an HTML form field

ProfileParameter—Represents the value of a Profile property

QueryStringParameter—Represents the value of a query string field

SessionParameter—Represents the value of an item stored in Session state

For example, the page in Listing 18.14 contains a DropDownList control and a GridView

control, which enables you to view movies that match a selected category (see Figure 18.3)

FIGURE 18.3 Displaying movies by category

LISTING 18.14 ShowMoviesByCategory.aspx

Trang 5

.movies

{

border:Solid 1px black;

}

.movies td,.movies th

{

padding:5px;

}

</style>

<title>Show Movies by Category</title>

</head>

<body>

<div>

<asp:DropDownList

id=”ddlMovieCategory”

DataSourceID=”srcMovieCategories”

DataTextField=”Name”

DataValueField=”Id”

ToolTip=”Movie Category”

<asp:Button

id=”btnSelect”

Text=”Select”

<asp:GridView

id=”grdMovies”

CssClass=”movies”

GridLines=”None”

id=”srcMovieCategories”

TypeName=”MovieCategories”

SelectMethod=”GetCategories”

id=”srcMovies”

TypeName=”MovieCategories”

Trang 6

Runat=”server”>

<asp:ControlParameter

Name=”CategoryId”

ControlID=”ddlMovieCategory” />

</SelectParameters>

</asp:ObjectDataSource>

</div>

</form>

</body>

</html>

The ObjectDataSource control in Listing 18.14 is bound to the component contained in

Listing 18.15 The ObjectDataSource control includes a SelectParameters collection The

SelectParameters collection contains a ControlParameter, which represents the current

value of the ddlMovieCategory DropDownList control

LISTING 18.15 MovieCategories.cs

using System;

using System.Data;

using System.Data.SqlClient;

using System.Web.Configuration;

public class MovieCategories

{

private readonly string _conString;

public SqlDataReader GetMovies(int categoryId)

{

// Create Command

cmd.CommandText = “SELECT Id,Title,Director,DateReleased “

+ “ FROM Movies WHERE CategoryId=@CategoryId”;

// Add parameters

cmd.Parameters.AddWithValue(“@CategoryId”, categoryId);

con.Open();

Trang 7

}

public SqlDataReader GetCategories()

{

// Create Command

cmd.CommandText = “SELECT Id,Name FROM MovieCategories”;

con.Open();

}

public MovieCategories()

{

_conString =

WebConfigurationManager.ConnectionStrings[“Movies”].ConnectionString;

}

Passing Objects as Parameters

Passing long lists of parameters to methods can make it difficult to maintain an

applica-tion If the list of parameters changes, you need to update every method that accepts the

list of parameters Rather than pass a list of parameters to a method, you can pass a

partic-ular object For example, you can pass a CompanyEmployee object to a method used to

update an employee, rather than a list of parameters that represent employee properties

If you specify a value for an ObjectDataSource control’s DataObjectTypeName property,

you can pass an object rather than a list of parameters to the methods that an

ObjectDataSource represents In that case, the ObjectDataSource parameters represent

properties of the object

For example, the EmployeeData component in Listing 18.16 contains an InsertEmployee()

method for creating a new employee This method is passed an instance of the

CompanyEmployee object that represents a particular employee The CompanyEmployee class

also is included in Listing 18.16

Trang 8

LISTING 18.16 EmployeeData.cs

using System;

using System.Data;

using System.Data.SqlClient;

using System.Collections.Generic;

using System.Web.Configuration;

public class EmployeeData

{

string _connectionString;

public void UpdateEmployee(CompanyEmployee employeeToUpdate)

{

// Initialize ADO.NET objects

SqlConnection con = new SqlConnection(_connectionString);

cmd.CommandText = “UPDATE Employees SET FirstName=@FirstName,” +

“LastName=@LastName,Phone=@Phone WHERE Id=@Id”;

// Create parameters

cmd.Parameters.AddWithValue(“@Id”, employeeToUpdate.Id);

cmd.Parameters.AddWithValue(“@FirstName”, employeeToUpdate.FirstName);

cmd.Parameters.AddWithValue(“@LastName”, employeeToUpdate.LastName);

cmd.Parameters.AddWithValue(“@Phone”, employeeToUpdate.Phone);

// Execute command

using (con)

{

con.Open();

cmd.ExecuteNonQuery();

}

public List<CompanyEmployee> GetEmployees()

{

List<CompanyEmployee> employees = new List<CompanyEmployee>();

SqlConnection con = new SqlConnection(_connectionString);

cmd.CommandText = “SELECT Id,FirstName,LastName,Phone FROM Employees”;

using (con)

{

con.Open();

Trang 9

SqlDataReader reader = cmd.ExecuteReader();

while (reader.Read())

{

CompanyEmployee newEmployee = new CompanyEmployee();

newEmployee.Id = (int)reader[“Id”];

newEmployee.FirstName = (string)reader[“FirstName”];

newEmployee.LastName = (string)reader[“LastName”];

newEmployee.Phone = (string)reader[“Phone”];

employees.Add(newEmployee);

}

return employees;

}

public EmployeeData()

{

_connectionString =

WebConfigurationManager.ConnectionStrings[“Employees”].ConnectionString;

}

public class CompanyEmployee

{

private int _id;

private string _firstName;

private string _lastName;

private string _phone;

public int Id

{

get { return _id; }

set { _id = value; }

}

public string FirstName

{

get { return _firstName; }

set { _firstName = value; }

}

public string LastName

{

get { return _lastName; }

set { _lastName = value; }

}

Trang 10

public string Phone

{

get { return _phone; }

set { _phone = value; }

}

The page in Listing 18.17 contains a DetailsView control and an ObjectDataSource

control The DetailsView control enables you to update existing employees in the

Employees database table

LISTING 18.17 UpdateEmployees.aspx

<title>Update Employees</title>

</head>

<body>

<div>

<asp:DetailsView ID=”DetailsView1”

DataSourceID=”srcEmployees”

AutoGenerateRows=”True”

AutoGenerateEditButton=”True”

AllowPaging=”true”

id=”srcEmployees”

TypeName=”EmployeeData”

DataObjectTypeName=”CompanyEmployee”

SelectMethod=”GetEmployees”

UpdateMethod=”UpdateEmployee”

</div>

</form>

</body>

</html>

Định dạng
Số trang	10
Dung lượng	452,77 KB