MVC5的模式構建網站(五)

這篇博客，來創建數據上下文。首先我在項目中新建一個DAL文件夾，用來作爲數據訪問層的。如有不懂請看圖

緊接着就是在文件夾裏面創建一個SchoolContext類，再往類裏面寫交接數據字段，請看下圖

在這裏先不理Seed，而Seed是爲了一些種子數據的，這是手動的輸入，這裏暫時不講，這裏繼續往DAL裏面創建SchoolInitializer類，然後往類裏面添加如下代碼，主要用於測試的。

public class SchoolInitializer : System.Data.Entity.DropCreateDatabaseIfModelChanges<SchoolContext>
    {
        protected override void Seed(SchoolContext context)
        {
            var students = new List<Student>
            {
            new Student{FirstName="Carson",LastName="Alexander",EnrollmentDate=DateTime.Parse("2005-09-01")},
            new Student{FirstName="Meredith",LastName="Alonso",EnrollmentDate=DateTime.Parse("2002-09-01")},
            new Student{FirstName="Arturo",LastName="Anand",EnrollmentDate=DateTime.Parse("2003-09-01")},
            new Student{FirstName="Gytis",LastName="Barzdukas",EnrollmentDate=DateTime.Parse("2002-09-01")},
            new Student{FirstName="Yan",LastName="Li",EnrollmentDate=DateTime.Parse("2002-09-01")},
            new Student{FirstName="Peggy",LastName="Justice",EnrollmentDate=DateTime.Parse("2001-09-01")},
            new Student{FirstName="Laura",LastName="Norman",EnrollmentDate=DateTime.Parse("2003-09-01")},
            new Student{FirstName="Nino",LastName="Olivetto",EnrollmentDate=DateTime.Parse("2005-09-01")}
            };

            students.ForEach(s => context.Students.Add(s));
            context.SaveChanges();
            var courses = new List<Course>
            {
            new Course{CourseID=1050,Title="Chemistry",Credits=3,},
            new Course{CourseID=4022,Title="Microeconomics",Credits=3,},
            new Course{CourseID=4041,Title="Macroeconomics",Credits=3,},
            new Course{CourseID=1045,Title="Calculus",Credits=4,},
            new Course{CourseID=3141,Title="Trigonometry",Credits=4,},
            new Course{CourseID=2021,Title="Composition",Credits=3,},
            new Course{CourseID=2042,Title="Literature",Credits=4,}
            };
            courses.ForEach(s => context.Courses.Add(s));
            context.SaveChanges();
            var enrollments = new List<Enrollment>
            {
            new Enrollment{StudentID=1,CourseID=1050,Grade=Grade.A},
            new Enrollment{StudentID=1,CourseID=4022,Grade=Grade.C},
            new Enrollment{StudentID=1,CourseID=4041,Grade=Grade.B},
            new Enrollment{StudentID=2,CourseID=1045,Grade=Grade.B},
            new Enrollment{StudentID=2,CourseID=3141,Grade=Grade.F},
            new Enrollment{StudentID=2,CourseID=2021,Grade=Grade.F},
            new Enrollment{StudentID=3,CourseID=1050},
            new Enrollment{StudentID=4,CourseID=1050,},
            new Enrollment{StudentID=4,CourseID=4022,Grade=Grade.F},
            new Enrollment{StudentID=5,CourseID=4041,Grade=Grade.C},
            new Enrollment{StudentID=6,CourseID=1045},
            new Enrollment{StudentID=7,CourseID=3141,Grade=Grade.A},
            };
            enrollments.ForEach(s => context.Enrollments.Add(s));
            context.SaveChanges();
        }
    }

寫了這麼多，要幹嘛的呢，這裏是要創建 EF，用試驗數據初始化數據庫，還有要到項目的更目錄裏面去改Web.config,修改如下代碼

<contexts>
    <context type="ContosoUniversity.DAL.SchoolContext, ContosoUniversity">
      <databaseInitializer type="ContosoUniversity.DAL.SchoolInitializer, ContosoUniversity" />
    </context>
  </contexts>

這裏我直接截圖演示

這個時候應用程序設置了當你在一個給定的運行的第一次訪問數據庫，這次的更新就到這裏，會有你喜歡的下次更新，這裏重新聲明一遍，這裏不會給你學到很多懂東西，而且這裏是在有一定的基礎的同學更新的，況且這麼簡單的代碼，我基本不加註釋，就像不會像石頭那樣貼標籤！