/// <summary>
/// 无实体链接删除添加
/// </summary>
/// <param name="context"></param>
/// <param name="blogs"></param>
public static void InserUpdateOrDeleteGraph(EFCoreDbContext context, Blog blogs)
{
var existingBlog = context.Blogs.Include(p => p.Posts).FirstOrDefault(b => b.Id == blogs.Id);
if (existingBlog == null)
{
context.Add(blogs);
}
else
{
context.Entry(existingBlog).CurrentValues.SetValues(blogs);
foreach (var post in blogs.Posts)
{
var existingPost = existingBlog.Posts.FirstOrDefault(p => p.Id == post.Id);
if (existingPost == null)
{
existingBlog.Posts.Add(post);
}
else
{
context.Entry(existingPost).CurrentValues.SetValues(post);
}
}
foreach (var post in existingBlog.Posts)
{
if (!blogs.Posts.Any(p => p.Id == post.Id))
{
context.Remove(post);
}
}
}
context.SaveChanges();
}
/// <summary> /// 更新 /// </summary> /// <typeparam name="T"></typeparam> /// <param name="model"></param> /// <returns></returns> public int Update <T>(T table) where T : class => TryCatchUpdateConcurrencyException(() => _db.Entry <T>(table).State = EntityState.Modified);
static void Main(string[] args)
{
using (var context = new EFCoreDbContext())
{
//TODO:EFCode不知道是否要创建，所以要手动去创建
//context.Database.EnsureDeleted();
//context.Database.EnsureCreated();
//TODO:手动调用EntityFramework Core内置API创建
//RelationalDatabaseCreator databaseCreator =
// (RelationalDatabaseCreator) context.Database.GetService<IDatabaseCreator>();
//databaseCreator.CreateTables();
//var student = context.Students.FirstOrDefault();
//var s = new Student()
//{
// Age = 1,
// Decimal = 1,
// Double = 1,
// Float = 1,
// CreateTime = DateTime.Now,
// Name = "chenjie"
//};
//context.Students.Add(s);
//context.SaveChanges();
//s.Name = "chenjielove";
//context.SaveChanges();
//context.Set<Customer>().AddRange(
// new Customer() { Name = "111"},
// new Customer() { Name = "222"}
// );
//context.SaveChanges();
//context.Blogs.Add(new Blog("http://www.cnblogs.com") {Name = "chenjie"});
//context.SaveChanges();
//foreach (var blog in context.Blogs)
//{
// Console.WriteLine($"{blog.Id}{blog.Name}{blog.Url}");
//}
//var student=new Student()
//{
// Age=1,
// Name = "chenjie",
// CreateTime = DateTime.Now
//};
//var course=new Course()
//{
// Name = "EntityFramework Core",
// Introduce = "轻量级、可扩展、跨平台",
// CreatedTime = DateTime.Now
//};
//student.AddCourse(course);
//context.Students.Add(student);
//context.SaveChanges();
//var courses = context.Set<Course>().Where(d => EF.Property<int>(d, "StudentId") == 1).ToList();
//var course=new Course
//{
// Introduce = "EntityFramework Core 2.0",
// Name = "EF Core"
//};
//context.Entry(course).Property("CreateTime").CurrentValue = DateTime.Now;
//context.SaveChanges();
//var blogs = context.Blogs.Include(d => d.Post).ToList();
//var blog = context.Blogs.Include(d => d.Post).IgnoreQueryFilters().AsNoTracking().ToList();
//var blogId = 1;
//var posts = context.Set<Post>().Where(d => EF.Property<int>(d, "BlogId") == blogId);
//var tags = new[]
//{
// new Tag{Text="1"},
// new Tag{Text="2"},
// new Tag{Text="3"},
// new Tag{Text="4"},
// new Tag{Text="5"},
//};
//var posts = new[]
//{
// new Post{Name="1"},
// new Post{Name="2"},
// new Post{Name="3"},
// new Post{Name="4"},
// new Post{Name="5"},
//};
//context.AddRange(new PostTag { Posts = posts[0], Tags = tags[0] },
// new PostTag { Posts = posts[1], Tags = tags[1] },
// new PostTag { Posts = posts[2], Tags = tags[2] },
// new PostTag { Posts = posts[3], Tags = tags[3] },
// new PostTag { Posts = posts[4], Tags = tags[4] });
//context.SaveChanges();
//var postss = context.Set<Post>().Include("PostTags.Tag").ToList();
//context.Payments.Add(new CashPayment {Amount = 2M, Name = "Tom"});
//context.Payments.Add(new CashPayment {Amount = 1000M, Name = "Jim"});
//context.Payments.Add(new CreditcardPayment()
//{
// Amount = 200000,
// Name = "招商银行",
// CreditcardNumber = "041647181912"
//});
//context.SaveChanges();
//var payments = context.Payments.ToList();
//foreach (var payment in payments)
//{
// Console.WriteLine($"{payment.Name}{payment.Amount}{payment.GetType().Name}");
//}
//var payments = context.Payments.ToList();
//foreach (var payment in context.Payments.OfType<CreditcardPayment>())
//{
// Console.WriteLine($"{payment.Name}{payment.Amount}{payment.GetType().Name}");
//}
//TODO: 当使用主键查询时使用Find方法性能会更好
//var blog = context.Blogs.Find(1);
//var blogs = context.Blogs.FirstOrDefault(d => d.Id == 1);
//TODO:复合主键
//var productCategory = context.Blogs.Find(1, 1);
//TODO:利用Find或者FindAsync方法不能进行饥饿加载(Include),但是我们任然能够通过上下文的Entry方法中的Navigations属性加载导航属性实现饥饿加载
//var student = context.Students.Find(Convert.ToInt32(3));
//foreach (var navigation in context.Entry(student).Navigations)
//{
// navigation.Load();
//}
//TODO:在继承映射TPH模式中，可以用OfType方法转换为具体类，所以此方法与查询运算符等值条件等价
//var patments = context.Payments.OfType<CashPayment>();
//Console.WriteLine(patments.FirstOrDefault()?.Name);
//TODO:也可以用Cast进行转换与OfType的区别是，Cast将翻译成In子句
//var payments = context.Payments.Cast<CashPayment>();
//Console.WriteLine(payments.FirstOrDefault()?.Name);
//TODO:EF Code不支持使用OfType和Cast转换原始类型
//var paymentss = context.Payments.Select(d => d.PaymentId).OfType<string>();
//Console.WriteLine(paymentss);
//TODO:C# 中可以使用if和as来进行类型转换。如果一个对象是某个类型或是其父类型，就返回true否则返回false，Is永远不会抛出异常，As会
//TODO:Is进行类型转换等同于Cast在sql中都会翻译成in子句
//var payments = context.Payments.Where(d => d is CashPayment);
//Console.WriteLine(payments.FirstOrDefault()?.Name);
//TODO:调用Select会翻译成Select子句，投影不仅支持实体，同时支持匿名函数
//var paymentss = context.Payments.Select(d => d.Name + " ");
//Console.WriteLine(paymentss.FirstOrDefault());
//TODO:DefaultIfEmpty常用于左连接，若查询序列为空，则返回实例类型默认值
//var blogs = context.Blogs.Where(d => d.Id == 0).DefaultIfEmpty();
//Console.WriteLine(blogs.FirstOrDefault()==default(Blog));
//TODO:DefaultIfEntity还有重载可接受一个指定的默认值，在EFCore中将不会翻译为SQL，而是在本地检查结果，如果没有行就会产生指定的默认值
//var defaultBlog = new Blog(){Name = nameof(Blog)};
//var blogss = context.Blogs.Where(d => d.Id == 0).DefaultIfEmpty(defaultBlog);
//Console.WriteLine(blogss.FirstOrDefault()?.Name);
//TODO:EFCore还不支持分组，它只优化了GroupBy,将GroupBy中的OrderBy子句进行了翻译，将SQL执行结果读取到本地，逐一进行分组
var blogs = context.Blogs.GroupBy(d => d.Id);
Console.WriteLine(blogs.FirstOrDefault()?.FirstOrDefault()?.Name);
//TODO:会翻译为inner join
var outerBlogs = context.Blogs;
var innerPosts = context.Set <Post>();
var outerBlogQuery = outerBlogs.Join(innerPosts, b => b.Id, p => p.BlogId,
((blog, post) => new { Id = blog.Id, Name = blog.Name }));
Console.WriteLine(outerBlogQuery.FirstOrDefault()?.Name);
//TODO:使用Select和SelectMany可以实现CROSS JOIN 交叉查询(求两个表的笛卡尔积)
var outerBlogQuert2 = outerBlogs.Select(b => new
{
Id = b.Id,
Name = b.Name,
Posts = innerPosts.Where(p => p.BlogId == b.Id)
}).SelectMany(collectionSelector: b => b.Posts,
resultSelector: (b, p) => new { Id = b.Id, Name = b.Name });
Console.WriteLine(outerBlogQuert2.FirstOrDefault()?.Name);
//TODO:GroupJoin最终被翻译成LeftJoin
var outerBlogQusert3 = outerBlogs.GroupJoin(inner: innerPosts, outerKeySelector: b => b.Id,
innerKeySelector: p => p.BlogId,
resultSelector: (b, p) => new { Id = b.Id, Name = b.Name, Posts = b.Posts });
Console.WriteLine(outerBlogQusert3.FirstOrDefault()?.Name);
//TODO:EFCore中不支持连接翻译SQL，支持本地和合并。下面代码会抛出异常。
var first = context.Blogs.Where(item => item.Id >= 1);
var second = context.Blogs.Where(item => item.Id <= 2);
var blogs2 = first.Concat(second).Select(d => new { Id = d.Id, Name = d.Name });
Console.WriteLine(blogs2.FirstOrDefault()?.Name);
//TODO:下面为本地合并
var first1 = context.Blogs.Where(item => item.Id >= 1).Select(d => d.Name);
var second1 = context.Blogs.Where(item => item.Id <= 2).Select(d => d.Name);
var name = first.Concat(second);
Console.WriteLine(name.FirstOrDefault());
//TODO:Skip和Take会转换成SQL中的OFFSET和LIMIT分页关键字
var blogs3 = context.Blogs.Skip(1).Take(10);
Console.WriteLine(blogs3.DefaultIfEmpty());
//TODO:EFCore中会将Contains转换成SQL中的In谓词
var blogs4 = context.Blogs.Select(d => d.Id).Contains(1);
Console.WriteLine(blogs4);
//TODO:EFCore中会将字符串的Contains转换成CHARINDEX
var blogs5 = context.Blogs.Select(d => d.Name.Contains("J"));
Console.WriteLine(blogs5.FirstOrDefault());
//TODO:EFCorez中会将数组集合的Contains翻译成In子句
var nameArray = new string[] { "a", "b", "c" };
var blogs6 = context.Blogs.Where(item => nameArray.Contains(item.Name));
Console.WriteLine(blogs6.FirstOrDefault()?.Name);
//TODO:EFCore中会将Any翻译EXISTS将All翻译成NOT EXISTS
var blogs7 = context.Blogs.Any(i => i.Id == 1);
var blogs8 = context.Blogs.All(item => item.Id == 1);
Console.WriteLine(blogs7);
Console.WriteLine(blogs8);
//TODO:在EFCore中使用Include可执饥饿加载，如果有多个导航属性，可以用Include，如果导航属性需要饥饿加载使用ThenInclude
var blogs9 = context.Blogs.Include(item => item.Posts);
//TODO:如果在Include后更改了查询结果，那么Include将会被忽略
var blogs10 = context.Blogs.Include(item => item.Posts).Select(b => new { ID = b.Id });
//TODO:EFCore1.1中添加的显示加载
var blogs11 = context.Blogs.FirstOrDefault();
context.Entry(blogs11).Collection(b => b.Posts).Load();
//TODO:调用原生SQL
var blogs12 = context.Blogs.FromSql <Blog>("select * from blogs").ToList();
//TODO:也可以使用字符串插值
var blogs13 = context.Blogs.FromSql($"select * from blogs where Id={1}");
//TODO:使用 FormattableString可以防止SQL注入 。调用原,生查询后同样可以用Include关联
FormattableString formattable = $"select * from blogs where Id={1}";
var blogs14 = context.Blogs.FromSql(formattable).Include(b => b.Posts).ToList();
//TODO:原生执行增删改操作
var commandSql = "Insert into blog(name,url) values(@name,@url)";
var sqlParameter = new SqlParameter[]
{
new SqlParameter("@name", System.Data.SqlDbType.NVarChar),
new SqlParameter("@url", System.Data.SqlDbType.NVarChar)
};
sqlParameter[0].Value = "张三";
sqlParameter[1].Value = "www.chenjieloveyou.com";
context.Database.ExecuteSqlCommand(commandSql, sqlParameter);
//批处理声明
var blogs15 = new Blog
{
CreatedTime = DateTime.Now,
ModifiedTime = DateTime.Now,
Name = "陈杰"
};
context.ChangeTracker.TrackGraph(blogs15, node =>
{
var entry = node.Entry;
if ((int)entry.Property("Id").CurrentValue < 0)
{
entry.State = EntityState.Added;
entry.Property("Id").IsTemporary = true;
}
else
{
entry.State = EntityState.Modified;
}
});
var excetingBlogs = context.Blogs.Find(1);
if (excetingBlogs == null)
{
context.Add(blogs);
}
else
{
context.Entry(excetingBlogs).CurrentValues.SetValues(blogs);
}
context.SaveChanges();
//TODO:无实体更新
var blogs17 = context.Blogs.Include(item => item.Posts).FirstOrDefault(item => item.Id == 2);
blogs17.Name = "aaa";
blogs17.Posts.All(p =>
{
p.Name = "bbb";
return(true);
});
context.Update(blogs17);
var result = context.SaveChanges();
//TODO:无实体更新无主键
var blogs18 = context.Blogs.Include(item => item.Posts).FirstOrDefault(item => item.Id == 2);
if (blogs18 == null)
{
context.Blogs.Add(blogs17);
}
else
{
context.Entry(blogs18).CurrentValues.SetValues(blogs17);
foreach (var post in blogs17.Posts)
{
var nowPost = blogs18.Posts.FirstOrDefault(item => item.Id == post.Id);
if (nowPost == null)
{
blogs18.Posts.Add(post);
}
else
{
context.Entry(nowPost).CurrentValues.SetValues(post);
}
}
}
context.SaveChanges();
//TODO:每个实体查询EF都会创建快照去追踪实体，如果要关闭追踪使用AsNoTracking()方法
var blogs19 = context.Blogs.AsNoTracking().ToList();
//TODO：使用我们重写的方法优化性能添加时，不需要快照追踪
for (int i = 0; i < 1000; i++)
{
context.AddRange(new Blog()
{
Name = i.ToString()
});
}
context.SaveChanges(true);
//TODO:在EF中我们可以用Contains，StartsWith，EndWith来做模糊查询，不过Contains转换成SQL之后是Charindex，StartsWith会生成夹带双重判断的SQL，一遍会通过通配符过滤，灵异方面会通过LEFT函数从左边截取长度等于字符串长度的条件，EndsWith不会用%通配符，而是使用Right函数从最后开始截取
//TODO:有了EF.Function.Like我们很方便的自定义模糊查询逻辑
var selectStr = "abcd";
var blogsStartWith = blogs19.Where(d => d.Name.StartsWith("J")).ToList();
var blogsEndWith = blogs19.Where(d => d.Name.EndsWith("J")).ToList();
var blogsLike = blogs19.Where(d => EF.Functions.Like(d.Name, "J%")).ToList();
var blogsLikeStr = blogs19.Where(d => EF.Functions.Like(d.Name, $"[{selectStr}]%"));
//TODO:我们可以用like的重载方法处理转义字符，最终会翻译成ESCAPE
var blogsLikeescape = blogs19.Where(d => EF.Functions.Like(d.Name, @"\J%", @"\")).ToList();
//TODO:EFCore重要特性之一显示编译查询
var query = EF.CompileQuery((EFCoreDbContext db, int id) => db.Blogs.FirstOrDefault(c => c.Id == id));
var queryBlog = query(context, 1);
var queryBlog2 = query(context, 1);
//TODO:自定义验证
if (context.ExecuteValidator().Any())
{
foreach (var error in context.ExecuteValidator())
{
Console.WriteLine(error.ErrorMessage);
}
}
}
RunText(regularTest: (blogIds) =>
{
using (var db = new EFCoreDbContext())
{
foreach (var id in blogIds)
{
var customer = db.Blogs.FirstOrDefault(c => c.Id == id);
}
}
}, compiledTest: (blogIds) =>
{
var query = EF.CompileQuery((EFCoreDbContext db, int id) => db.Blogs.FirstOrDefault(c => c.Id == id));
using (var db = new EFCoreDbContext())
{
foreach (var id in blogIds)
{
var customer = query(db, id);
}
}
});
//TODO:使用不依赖注入构造DbContextOptions
_contextOptions = new DbContextOptionsBuilder().UseSqlServer(args[0]).Options;
}