EF 一个简单的使用

原文：https://www.cnblogs.com/leotsai/p/entity-framework-doesnt-need-additional-repository.html

花猫.NET的评论里面的代码

记录一下

1、创建的控制台程序，NuGet引用了EF。里面用了序列号，需要引用Newtonsoft.Json

2、数据库用的现成的，已经有表和数据了。数据库名MyDbContext，表Students

3、在app.config中添加配置项，添加到configSections这个节点后面，和它同级。

<connectionStrings>

    <add name="MyDbContext" connectionString="Data Source=.\sqlexpress;Database=MyDbContext;UID=sa;PWD=sa;" providerName="System.Data.SqlClient"></add>

</connectionStrings>

全部代码

基本使用

//基本使用

    public class Class4

    {

        public void test1()

        {

            Console.WriteLine();

            using (var db = DbFactory.Create())

            {

                //db....

                //db.SaveChange();

                //测试1 打印students表的所有数据

                var list = db.All<Students>().ToList();

                var str = JsonConvert.SerializeObject(list);

                Console.WriteLine(str);

                //测试2 添加一个学生

                Students student1 = new Students

                {

                    Name = "name12",

                    Age = ,

                };

                db.Insert<Students>(student1);

                db.SaveChanges();

            }

        }

    }

自定义代码

    //自定义代码

    public class Students

    {

        public int Id { get; set; }

        public string Name { get; set; }

        public int Age { get; set; }

        public DateTime? CreateTime { get; set; }

    }

    public class MyDbContext : DbContext

    {

        public MyDbContext(string connectionName) : base(connectionName) { }

        public DbSet<Students> Orders { get; set; }

    }

通用代码引用了 MyDbContext

    //原文：https://www.cnblogs.com/leotsai/p/entity-framework-doesnt-need-additional-repository.html

    //花猫.NET的评论里面的代码

    //通用代码 引用了 MyDbContext

    public class DbFactory

    {

        public static IRepository Create()

        {

            return new EfRepository(new MyDbContext("MyDbContext"));

        }

    }

    public interface IRepository : IDisposable

    {

        int SaveChanges();

        IQueryable<T> All<T>() where T : class;

        T Get<T>(Expression<Func<T, bool>> conditions) where T : class;

        void Insert<T>(T entity) where T : class;

        void Update<T>(T entity) where T : class;

        void Delete<T>(T entity) where T : class;

        void Delete<T>(Expression<Func<T, bool>> conditions) where T : class;

        List<T> Find<T>(Expression<Func<T, bool>> conditions = null) where T : class;

        List<T> Find<T, S>(Expression<Func<T, bool>> conditions, Expression<Func<T, S>> orderBy, int pageSize, int pageIndex, out int totalCount) where T : class;

        List<T> SqlQuery<T>(string sql);

        int ExecuteSqlCommand(string sql);

        long GetNextSequenceValue(string sequenceName);

    }

    public class EfRepository : IRepository

    {

        private DbContext context;

        public EfRepository(DbContext dbcontext)

        {

            context = dbcontext;

        }

        #region IRepository

        public IQueryable<T> All<T>() where T : class

        {

            return context.Set<T>().AsNoTracking();

        }

        public void Update<T>(T entity) where T : class

        {

            var entry = context.Entry(entity);

            if (entry.State == EntityState.Detached)

            {

                context.Set<T>().Attach(entity);

            }

            entry.State = EntityState.Modified;

        }

        public void Insert<T>(T entity) where T : class

        {

            context.Set<T>().Add(entity);

        }

        public void Delete<T>(T entity) where T : class

        {

            var entry = context.Entry(entity);

            if (entry.State == EntityState.Detached)

            {

                context.Set<T>().Attach(entity);

            }

            entry.State = EntityState.Deleted;

            context.Set<T>().Remove(entity);

        }

        public void Delete<T>(Expression<Func<T, bool>> conditions) where T : class

        {

            var list = Find<T>(conditions);

            foreach (var item in list)

            {

                Delete<T>(item);

            }

        }

        public T Get<T>(Expression<Func<T, bool>> conditions) where T : class

        {

            return All<T>().FirstOrDefault(conditions);

        }

        public List<T> Find<T>(Expression<Func<T, bool>> conditions = null) where T : class

        {

            if (conditions != null)

            {

                return All<T>().Where(conditions).ToList();

            }

            else

            {

                return All<T>().ToList();

            }

        }

        public List<T> Find<T, S>(Expression<Func<T, bool>> conditions, Expression<Func<T, S>> orderBy, int pageSize, int pageIndex, out int totalCount) where T : class

        {

            var queryList = conditions == null ?

                All<T>() :

                All<T>().Where(conditions);

            totalCount = queryList.Count();

            return queryList.OrderByDescending(orderBy).Skip((pageIndex - ) * pageSize).Take(pageSize).ToList();

        }

        public List<T> SqlQuery<T>(string sql)

        {

            return context.Database.SqlQuery<T>(sql).ToList();

        }

        public int ExecuteSqlCommand(string sql)

        {

            return context.Database.ExecuteSqlCommand(sql);

        }

        public int SaveChanges()

        {

            return context.SaveChanges();

        }

        public void Dispose()

        {

            context.Dispose();

        }

        public long GetNextSequenceValue(string sequenceName)

        {

            var rawQuery = context.Database.SqlQuery<long>(string.Format("SELECT NEXT VALUE FOR {0}", sequenceName)).ToList();

            long nextVal = rawQuery.Single();

            return nextVal;

        }

        #endregion

    }

巴特西

EF 一个简单的使用

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