使用主键属性 每个实体必须有主键 默认值的id属性值必须为0 在context2中,它不知道实体的状态, 只能通过实体的主键来判断实体的状态 如果主键为0,则是新的对象,不为0 就是修改 Standard disconnectedStandard = null; using (var context = new SchoolDBEntities()) { context.Configuration.ProxyCreationEnabled = false; disconnectedStandar…

//Create student in disconnected mode Student newStudent = new Student() { StudentName = "New Single Student" }; //Assign new standard to student entity newStudent.Standard = new Standard() { StandardName = "New Standard" }; //add new…

Update Entity Graph using DbContext: Updating an entity graph in disconnected scenario is a complex task. It is easy to add a new entity graph in disconnected mode, but to update an entity graph needs careful design consideration. The problem in upda…

using System; using System.Collections.Generic; public partial class Student { public Student() { this.Courses = new HashSet<Course>(); } public int StudentID { get; set; } public string StudentName { get; set; } public Nullable<int> StandardI…

Student studentToDelete; . Get student from DB using (var ctx = new SchoolDBEntities()) { studentToDelete = ctx.Students.Where(s => s.StudentName == "Student1").FirstOrDefault<Student>(); } //Create new context for disconnected scenario…

可以为实体实现自定义验证,重写DBContext中的个ValidateEntity方法 protected override System.Data.Entity.Validation.DbEntityValidationResult ValidateEntity(DbEntityEntry entityEntry, System.Collections.Generic.IDictionary<object, object> items) { if (entityEntry.Entity is…

You can change the color of an entity in the designer so that it would be easy to see related groups of entities in the designer from Visual Studio 2012 onwards. To change the color of an entity, select entity in the designer → go to property window…

Add Entity Graph using DbContext: Adding entity graph with all new entities is a simple task. We can use DbSet.Add() method to attach a whole entity graph to the context and set all the entity's states to Added as we have seen in theprevious section.…

如何把断开的实体添加到新的context上下文中 1.首先,我们需要把实体附加到新的context上下文实例中. 2.其次,手动的给实体设置适当的实体状态,因为新的context上下文不知道断开的实体上有什么操作. DbSet.Add(): 把实体添加到context上下文,并自动设置实体的属性为added状态 //disconnected entity graph Student disconnectedStudent = new Student() { StudentName = "New…

<configSections> <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 --> <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFramewor…