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[英]EF Core, How to update a record in table which has both One To Many and Many to Many relationships with the same entity
[英]How to add/update many to many relations with one end of entity in EF core
我们已经访问了 EF Core 上的许多链接,进行了多对多更新,但无法为我们的问题找到具体的答案并明确我们的理解。
场景:我们希望一次性添加/更新一个实体及其相关的多对多关系,如(dbset.Add() 或 dbset.Update())
我们正在尝试以下操作,只能添加/更新父实体而不是多对多关系列表。 你能帮我们知道我们错在哪里吗? 可以做什么?
当前模型结构:
public class Teacher
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity), Required]
public long Id { get; set; }
public string Name { get; set; }
public List<TeacherDuty> TeacherDuties { get; set; }
}
public class Duty
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity), Required]
public long Id { get; set; }
public string Description { get; set; }
public List<TeacherDuty> TeacherDuties { get; set; }
}
public class TeacherDuty
{
public long TeacherId { get; set; }
public Teacher Teacher { get; set; }
public long DutyId { get; set; }
public Duty Duty { get; set; }
}
我们正在尝试使用以下方法添加/更新:
public async Task<Teacher> AddTeacher(Teacher pTeacher)
{
try
{
return await _teacher.AddAsync(pTeacher);
}
catch (Exception ex) { throw ex; }
}
public async Task<Teacher> UpdateTeacher(Teacher pTeacher)
{
try
{
return await _teacher.Update(pTeacher);
}
catch (Exception ex) { throw ex; }
}
如果可能,请指出我们对概念和解决方案的误解。 谢谢。
我创建了一个演示来添加和编辑教师。( _context
是数据库上下文)
添加老师:
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create(Teacher teacher)
{
//get your desired dutyId with your own logic
var SelectedDutyIds = new int[] { 1 };
var teacherDuties = new List<TeacherDuty>();
if (ModelState.IsValid)
{
_context.Add(teacher);
await _context.SaveChangesAsync();
foreach (var id in SelectedDutyIds)
{
var item = new TeacherDuty()
{
TeacherId = teacher.Id,
DutyId = id,
};
teacherDuties.Add(item);
}
_context.AddRange(teacherDuties);
await _context.SaveChangesAsync();
return RedirectToAction(nameof(Index));
}
return View(teacher);
}
编辑教师:首先删除教师现有的所有教师TeacherDuties
,然后添加新的教师TeacherDuties
。
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Edit(long id, Teacher teacher)
{
if (id != teacher.Id)
{
return NotFound();
}
if (ModelState.IsValid)
{
try
{
//your new dutyIds
var newSelectedDutyIds = new int[] { 3 };
var teacherDuties = new List<TeacherDuty>();
var tdList = await _context.TeacherDuties.Where(td => td.TeacherId == teacher.Id).ToListAsync() ;
_context.RemoveRange(tdList);
foreach (var newid in newSelectedDutyIds)
{
var item = new TeacherDuty()
{
TeacherId = teacher.Id,
DutyId = newid,
};
teacherDuties.Add(item);
}
_context.AddRange(teacherDuties);
_context.Update(teacher);
await _context.SaveChangesAsync();
}
catch (DbUpdateConcurrencyException)
{
if (!TeacherExists(teacher.Id))
{
return NotFound();
}
else
{
throw;
}
}
return RedirectToAction(nameof(Index));
}
return View(teacher);
}
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