此代码以前对我有用,但我不确定是什么导致了这个错误。我唯一的猜测是,当我尝试创建一个播放器时,团队数据将被发送回Team表并尝试复制,但由于TeamId是唯一的,因此出现此错误。
错误
INSERT语句与FOREIGN KEY约束“FK_dbo.Players_dbo.Teams_TeamId”冲突。冲突发生在数据库“Web”,表“dbo.Teams”,列'TeamId'中。该声明已被终止。
播放器
public class Player
{
...
...
[HiddenInput(DisplayValue = false)]
[ForeignKey("Team")]
public int TeamId { get; set; }
public virtual Team Team { get; set; }
...
}
队
public class Team
{
[Key]
[HiddenInput(DisplayValue = false)]
public int TeamId { get; set; }
....
public virtual ICollection<Player> Players { get; set; }
}
控制器
//
// GET: /Player/
[HttpGet]
public ActionResult Create()
{
PopulateTeamsDropDownList();
return View();
}
//
// POST: /Player/
[HttpPost]
public ActionResult Create(Player model)
{
if (ModelState.IsValid)
{
using (var db = new EfDb())
{
var userProfile = db.UserProfiles.Single(u => u.UserName == User.Identity.Name);
if (userProfile != null)
{
var player = new Player
{
UserProfile = userProfile,
....
....
};
db.Players.Add(player);
db.SaveChanges();
}
}
}
PopulateTeamsDropDownList(model.TeamId);
return View(model);
}
private void PopulateTeamsDropDownList(object selectedTeams = null)
{
var teamsQuery = from d in _iService.Teams
orderby d.Name
select d;
ViewBag.TeamID = new SelectList(teamsQuery, "TeamId", "Name", selectedTeams);
}
查看
<div class="editor-label">
@Html.LabelFor(model => model.TeamId, "Pick Your Team")
</div>
<div class="editor-field">
@Html.DropDownList("TeamId", String.Empty)
@Html.ValidationMessageFor(model => model.TeamId)
</div>
如何解决此错误?
答案 0 :(得分:10)
这背后的原因是当您在child
表上插入记录时,parent
表上的引用列的值尚不存在。
考虑以下情况:
// PARENT TABLE
CREATE TABLE TableA
(
ID INT PRIMARY KEY
);
// CHILD TABLE
CREATE TABLE TableB
(
ID INT PRIMARY KEY,
TableA_ID INT,
CONSTRAINT tb_FK FOREIGN KEY (TableA_ID) REFERENCES TableA(ID)
);
// RECORDS OF PARENT TABLE
INSERT INTO TableA (ID) VALUES (1);
INSERT INTO TableA (ID) VALUES (2);
// RECORDS OF CHILD TABLE
INSERT INTO TableB (ID, TableA_ID) VALUES (1,1);
INSERT INTO TableB (ID, TableA_ID) VALUES (2,1);
INSERT INTO TableB (ID, TableA_ID) VALUES (3,2);
如果您执行上述语句,它将不会失败,因为它们都不违反参照完整性规则。
尝试执行以下语句:
INSERT INTO TableB (ID, TableA_ID) VALUES (3,4);
它失败,因为4
TableA_ID
的值Table1.ID
在{{1}}上不存在。外键保留了记录之间的参照完整性。
答案 1 :(得分:8)
您应该尝试为玩家实体完成团队等实体。特别是外键。
[HttpPost]
public ActionResult Create(Player model)
{
if (ModelState.IsValid)
{
using (var db = new EfDb())
{
//Since you have the username cached, you can check the local EF cache for the object before hitting the db.
//var userProfile = db.UserProfiles.Single(u => u.UserName == User.Identity.Name);
var userProfile = db.UserProfiles.Local.SingleOrDefault(u => u.UserName == User.Identity.Name)
?? db.UserProfiles.SingleOrDefault(u => u.UserName == User.Identity.Name);
if (userProfile != null)
{
var player = new Player
{
UserProfile = userProfile,
....
....
};
player.TeamId = 5;
db.Players.Add(player);
db.SaveChanges();
}
}
}
PopulateTeamsDropDownList(model.TeamId);
return View(model);
}
并确保您视图中的Dropdown是必需的,并将正确的值发送到post方法。