public async Task Handle(AddNewCourseCommand command)
{
var newCourse = new Course
{
Name = command.Name,
Duration = command.Duration
};
dbcontext.Set <Course>().Add(newCourse);
postCommitEvent.PostCommit += () => command.CreatedCourseId = newCourse.Id;
}
public BaseRepository(SampleDBContext context)
{
this.context = context;
this.dbSet = context.Set <TEntity>();
}
static void Main(string[] args)
{
using (SampleDBContext BlogDBContext = new SampleDBContext())
{
BlogDBContext.Set <Publisher>().Add(new Publisher()
{
Name = "测试发布者",
Blogs = new List <Blog>()
{
new Blog()
{
Content = "测试博客 A"
},
new Blog()
{
Content = "测试博客 B"
},
new Blog()
{
Content = "测试博客 C"
},
}
});
BlogDBContext.SaveChanges();
/* 存在外键约束，博客的PublisherID必须为数据库内当前已经存在的值，
* 需要先保存发布者信息至数据库，否则空降博客会导致外键约束失败 */
BlogDBContext.Blogs.Add(
new Blog()
{
Content = "空降一篇博客",
PublisherID = BlogDBContext.Publishers.First(Publisher => Publisher.Name == "测试发布者").PublisherID
});
/* 存在外键约束，博客的PublisherID必须为数据库内当前已经存在的值，
* 下面使用 PublisherID=10101 发布博客将会失败 */
//BlogDBContext.Blogs.Add(new Blog() { Content = "幽灵博客", PublisherID=10101});
BlogDBContext.SaveChanges();
//!!! 解决延迟加载导致空对象问题：在目标数据表后使用 .Include("扩展数据表") 包含扩展数据表即可，此方法包含在 Microsoft.EntityFrameworkCore 命名空间需要 using ;
//foreach (Publisher publisher in BlogDBContext.Publishers.Include("Blogs"))
// Console.WriteLine(publisher.Name + " " + publisher.Blogs.Count);
Console.WriteLine("《测试博客 B》 的发布者为 : " + BlogDBContext.Blogs.First(Blog => Blog.Content == "测试博客 B").Publisher.Name);
//TODO: 遗留问题-1：通过种子数据添加的 BlogDBContext.Publishers.First(Publisher => Publisher.Name == "测试发布者").Blogs.Count 会输出 1 (应为4)
//Console.WriteLine($"测试发布者 发布了 {BlogDBContext.Blogs.Where(blog => blog.PublisherID == BlogDBContext.Publishers.FirstOrDefault(publisher => publisher.Name == "测试发布者").PublisherID).Count()} 篇博客。");
Console.WriteLine($"种子发布者-2 发布了 {BlogDBContext.Publishers.First(Publisher => Publisher.Name == "种子发布者-2")?.Blogs?.Count.ToString()??"*"} 篇博客。");
Console.WriteLine(string.Empty);
Console.WriteLine("Blogs.Count : " + BlogDBContext.Blogs.Count().ToString());
Console.WriteLine("Blogs :");
//TODO: 遗留问题-2：通过种子数据添加的{blog.Publisher?.Name ?? "*"} 会输出 * (应为博客发布者名称)
foreach (Blog blog in BlogDBContext.Blogs)
{
Console.WriteLine($"\t{blog.Content} \tvia : {blog.Publisher?.Name ?? "*"}\t(ID : {blog.PublisherID})");
}
//Console.WriteLine($"\t{blog.Content} \tvia : {BlogDBContext.Publishers.First(publisher => publisher.PublisherID == blog.PublisherID).Name}\t(ID : {blog.PublisherID})");
Console.WriteLine(string.Empty);
Console.WriteLine("Publishers.Count : " + BlogDBContext.Publishers.Count().ToString());
Console.WriteLine("Publishers :");
foreach (Publisher publisher in BlogDBContext.Publishers)
{
Console.WriteLine($"\t{publisher.Name} \t(ID : {publisher.PublisherID})\t发布数 : {publisher.Blogs.Count}");
}
}
Console.Read();
}
