如何使用EntityFramework将对象更新保存到数据库？

Question

我有以下情形：

public void UpdateEmployee(int empId, int deptId, int level) 
{ 
    Employee emp = GetEmployee(empId); 
    emp.DeptId = deptId; 
    emp.Level = level; 

    using (var mye = new MyEntity()) 
    { 
    //this is having no effect? 
    wc.SaveChanges() 
    } 
} 

我不知道如何保存Employee对象更新到数据库中。员工确实存在于数据库中。在使用块中应该怎么做？

Answer 1

连接它修改前，修改，然后保存更改。

public void UpdateEmployee(int empId, int deptId, int level) 
{ 
    Employee emp = GetEmployee(empId); 

    using (var dbContext = new MyDbContext()) 
    { 
    dbContext.Employees.Attach(emp); 
    emp.DeptId = deptId; 
    emp.Level = level; 
    //this is having no effect? 
    dbContext.SaveChanges() 
    } 
} 

你也可以将其固定，然后将状态设置为修改：

public void UpdateEmployee(int empId, int deptId, int level) 
{ 
    Employee emp = GetEmployee(empId); 
    emp.DeptId = deptId; 
    emp.Level = level;  

    using (var dbContext = new MyDbContext()) 
    { 
    dbContext.Employees.Attach(emp); 
    dbContext.Entry(emp).State = EntityState.Modified; 
    dbContext.SaveChanges() 
    } 
} 

如果你只想在更新，而不是所有列发送这些字段：

public void UpdateEmployee(int empId, int deptId, int level) 
{ 
    Employee emp = GetEmployee(empId); 
    emp.DeptId = deptId; 
    emp.Level = level;  

    using (var dbContext = new MyDbContext()) 
    { 
    dbContext.Employees.Attach(emp); 
    dbContext.Entry(emp).Property(p => p.DeptId).IsModified = true; 
    dbContext.Entry(emp).Property(p => p.Level).IsModified = true; 
    dbContext.SaveChanges() 
    } 
} 

Answer 2

你需要调用SaveChanges您的ObjectContext