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📜  ASP.Net Web表单模型绑定

📅  最后修改于: 2020-12-28 00:35:24             🧑  作者: Mango

ASP.NET Web窗体模型绑定

本主题说明如何使用“模型绑定”和“ Web表单”处理数据。与处理诸如ObjectDataSource或SqlDataSource之类的数据源对象相比，模型绑定使数据交互更直接。

在本教程中，我们将使用数据的实体框架和GridView在网页上显示数据。在这里，我们正在创建一个示例，其中包括以下步骤。

  • 创建一个ASP.NET Web应用程序

    • ASP模型构建1

  • 选择模板

    • 选择“模板”作为“ Web表单”，然后将身份验证更改为单个用户帐户。

    ASP模型构建2

  • 创建母版页

    • 使用母版页模板创建一个新的Web表单。我们将使用此母版页显示模型数据。

    ASP模型构建3

  • 创建数据模型和数据库

    • 我们将使用代码优先迁移来创建对象和相应的数据库表。这些表将存储有关学生及其课程的信息。

    在“模型”文件夹中创建一个新的模型类。

// StudentModels.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using System.ComponentModel.DataAnnotations;
namespace ModelBindingDemo.Models
{
public class SchoolContextDemo : DbContext
    {
public DbSet Students { get; set; }
public DbSet Enrollments { get; set; }
public DbSet Courses { get; set; }
    }
public class Student
    {
        [Key, Display(Name = "Email ID")]
        [ScaffoldColumn(false)]
public int StudentID { get; set; }
        [Required, StringLength(40), Display(Name = "Last Name")]
public string LastName { get; set; }
        [Required, StringLength(20), Display(Name = "First Name")]
public string FirstName { get; set; }
        [Required, StringLength(50), Display(Name = "Email ID")]
public string Email { get; set; }
        [EnumDataType(typeof(AcademicYear)), Display(Name = "Academic Year")]
public AcademicYear Year { get; set; }
public virtual ICollection Enrollments { get; set; }
    }
public class Enrollment
    {
        [Key]
public int EnrollmentID { get; set; }
public int CourseID { get; set; }
public int StudentID { get; set; }
public decimal? Grade { get; set; }
public virtualCourse Course { get; set; }
public virtualStudent Student { get; set; }
    }
public class Course
    {
        [Key]
public int CourseID { get; set; }
public string Title { get; set; }
public int Credits { get; set; }
public virtual ICollection Enrollments { get; set; }
    }
public enum AcademicYear
    {
        Freshman,
        Sophomore,
        Junior,
        Senior
    }
}

SchoolContextDemo类派生自DbContext，后者管理数据库连接和数据更改。

我们将使用代码优先迁移工具基于这些类建立数据库。遵循视图->其他窗口-> Package Manager控制台，从菜单栏中打开Package Manager控制台。

它将提示在Visual Studio IDE底部的屏幕。我们需要在此控制台中执行以下命令。

enable-migrations -Force -ContextTypeName ModelBindingDemo.Models.SchoolContextDemo

执行上述命令后，将产生以下输出。

之后，将创建一个名为Configuration.cs的新文件。该文件在创建后自动打开。该类包含一个Seed方法，使我们能够使用测试数据预先填充数据库表。

在这里，我们将一些数据添加到配置文件中，以便在网页上向用户显示。将数据添加到文件后，我们的Configuration.cs文件如下所示：

// Configuration.cs

namespace ModelBindingDemo.Migrations
{
using System;
using System.Data.Entity;
using System.Data.Entity.Migrations;
using System.Linq;
using ModelBindingDemo.Models;
internal sealed class Configuration : DbMigrationsConfiguration
    {
public Configuration()
        {
            AutomaticMigrationsEnabled = false;
        }
protected override void Seed(ModelBindingDemo.Models.SchoolContextDemo context)
        {
            context.Students.AddOrUpdate(
new Student
                 {
                     FirstName = "M. Irfan",
                     LastName = "Khan",
                     Email = "irfan@example.com",
                     Year = AcademicYear.Freshman
                 },
new Student
                 {
                     FirstName = "Arvind",
                     LastName = "Kumar",
                     Email = "Arvind@example.com",
                     Year = AcademicYear.Freshman
                 },
new Student
                 {
                     FirstName = "Arturo",
                     LastName = "Anand",
                     Email = "Anand@example.com",
                     Year = AcademicYear.Sophomore
                 },
new Student
                 {
                     FirstName = "Moris",
                     LastName = "Mano",
                     Email = "moris@example.com",
                     Year = AcademicYear.Sophomore
                 },
new Student
                 {
                     FirstName = "Roman",
                     LastName = "Sigh",
                     Email = "roman@example.com",
                     Year = AcademicYear.Junior
                 },
new Student
                 {
                     FirstName = "Jimmi",
                     LastName = "Seth",
                     Email = "jimmi@example.com",
                     Year = AcademicYear.Junior
                 },
new Student
                 {
                     FirstName = "Shayam",
                     LastName = "Rana",
                     Email = "Shayam@example.com",
                     Year = AcademicYear.Senior
                 },
new Student
                 {
                     FirstName = "Jecub",
                     LastName = "Cunto",
                     Email = "Nino@example.com",
                     Year = AcademicYear.Senior
                 }
                 );
         context.SaveChanges();
            context.Courses.AddOrUpdate(
new Course { Title = "Chemistry", Credits = 3 },
new Course { Title = "Microeconomics", Credits = 3 },
new Course { Title = "Macroeconomics", Credits = 3 },
new Course { Title = "Calculus", Credits = 4 },
new Course { Title = "Trigonometry", Credits = 4 },
new Course { Title = "Composition", Credits = 3 },
new Course { Title = "Literature", Credits = 4 }
                );
         context.SaveChanges();
            context.Enrollments.AddOrUpdate(
new Enrollment { StudentID = 1, CourseID = 1, Grade = 1 },
new Enrollment { StudentID = 1, CourseID = 2, Grade = 3 },
new Enrollment { StudentID = 1, CourseID = 3, Grade = 1 },
new Enrollment { StudentID = 2, CourseID = 4, Grade = 2 },
new Enrollment { StudentID = 2, CourseID = 5, Grade = 4 },
new Enrollment { StudentID = 2, CourseID = 6, Grade = 4 },
new Enrollment { StudentID = 3, CourseID = 1 },
new Enrollment { StudentID = 4, CourseID = 1 },
new Enrollment { StudentID = 4, CourseID = 2, Grade = 4 },
new Enrollment { StudentID = 5, CourseID = 3, Grade = 3 },
new Enrollment { StudentID = 6, CourseID = 4 },
new Enrollment { StudentID = 7, CourseID = 5, Grade = 2 }
                );
         context.SaveChanges();
        }
    }
}

之后，在Package Manager控制台中，运行以下命令。

PM> add-migration initial

和

PM> update-database

现在，已创建一个数据库并将其添加到App_Data文件夹下的项目中。

现在，让我们将数据从创建的数据库显示到网页上。我们将使用GridView控件以网格形式显示数据。 Student.aspx文件如下所示：

// Student.aspx

<%@PageTitle="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" 
CodeBehind="Students.aspx.cs" Inherits="ModelBindingDemo.Students" %>

背后的代码

// Student.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using ModelBindingDemo.Models;
using System.Data.Entity;
namespace ModelBindingDemo
{
public partial class Students : System.Web.UI.Page
    {
protected void Page_Load(object sender, EventArgs e)
        {
        }
public IQueryable studentsGrid_GetData()
        {
SchoolContextDemo db = newSchoolContextDemo();
var query = db.Students.Include(s => s.Enrollments.Select(e => e.Course));
return query;
        }
    }
}

最后，我们的项目如下所示。

输出：

在浏览器中运行Student.aspx文件作为视图，它将产生以下输出。