c# - 未创建 Entity Framework 数据库

Question

我首先在一个简单的 MVC3 应用程序中使用 EF4 代码。正确的连接字符串被上下文对象拾取，初始化构造函数被调用，OnModelCreating 方法也是如此，但种子方法永远不会被调用，数据库也不会被创建。有什么想法吗？

protected void Application_Start()
{
    Database.SetInitializer<SchoolContext>(new SchoolInitializer());
    SchoolContext context = new SchoolContext();
    context.Database.CreateIfNotExists();
    ...
}

public class SchoolInitializer : DropCreateDatabaseAlways<SchoolContext>
{
    public SchoolInitializer()
    {
    }
    protected override void Seed(SchoolContext context)
    {
        var students = new List<Student>
        {
            new Student {StudentId = Guid.NewGuid(), Name = "Carson" },
            new Student {StudentId = Guid.NewGuid(), Name = "Meredith" }
        };
        students.ForEach(s => context.Students.Add(s));
        context.SaveChanges();
    }
}

public class Student
{
    [Key]
    public Guid StudentId;
    public string Name;
}

public class SchoolContext : DbContext
{
    public DbSet<Student> Students { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
    }
}

配置:

<connectionStrings>
    <add name="SchoolContext" connectionString="Data Source=|DataDirectory|School.sdf" providerName="System.Data.SqlServerCe.4.0" />
</connectionStrings>

抛出的异常我认为只是提示数据库还没有创建:

[ModelValidationException: One or more validation errors were detected during model generation:

.Data.Edm.EdmEntityType: : EntityType 'Student' has no key defined. Define the key for this EntityType.System.Data.Edm.EdmEntitySet: EntityType: EntitySet �Students� is based on type �Student� that has no keys defined.

Answer 1

您的模型无效 - Student 实体没有定义键，并且在模型有效之前不会触发数据库创建。

您应该向您的 StudentId 添加访问器。这将使模型有效并触发数据库创建

public Guid StudentId { get; set; }