The UPDATE statement conflicted with the FOREIGN KEY constraint in asp.net mvc 5
Question
I am getting this error:
The UPDATE statement conflicted with the FOREIGN KEY constraint "FK_TitleMember". The conflict occurred in database "ParishDBSQL", table "dbo.Titles", column 'title_id'. The statement has been terminated.
controller
Get Action
public ActionResult Edit(int? id)
{
var member = (from h in db.Members
join f in db.Titles on h.title_id equals f.title_id
where h.m_id == id
select new
{
title_id = h.title_id,
}).First();
var viewmodel = new MembersViewModel();
viewmodel.title_id = member.title_id;
ViewBag.Titles = new SelectList(db.Titles.ToList(), "title_id", "Titles", viewmodel.title_id);
return View(viewmodel);
}
Post Action
public ActionResult Edit(MembersViewModel vm)
{
if (ModelState.IsValid)
{
var member = db.Members.Find(vm.m_id);
member.title_id = vm.title_id;
ViewBag.Titles = new SelectList(db.Titles.ToList(), "title_id", "Titles", vm.title_id);
db.Members.Attach(member);
db.Entry(member).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
return View(vm);
View
<div class="col-md-4">
<div class="form-group">
<label>Title</label>
@Html.DropDownList("Titles")
@Html.ValidationMessageFor(model => model.title_id)
</div>
</div>
Model
public partial class Title
{
public Title()
{
this.Heads = new HashSet<Head>();
this.Members = new HashSet<Member>();
}
public int title_id { get; set; }
public string Titles { get; set; }
public virtual ICollection<Head> Heads { get; set; }
public virtual ICollection<Member> Members { get; set; }
}
Viewmodel
public class MembersViewModel
{
public int m_id { get; set; }
public string titles { get; set; }
public int title_id { get; set; }
}
I want to update a title_id using a dropdownlist on my members table table but I get the error that is shown above.
2 answers
solution1
3 ACCPTED 2014-12-04 12:43:38
i think that the error is in this line
member.title_id = vm.title_id
maybe vm.title_id it is not found in primary table and it could not be a foreign key. Check the correct value of this variable
if it doesn't solve your problem looking at your code I saw some thinghs that I didn't understand very well.
try to change your code in this way
if (ModelState.IsValid)
{
var member = db.Members.Find(vm.m_id);
member.title_id = vm.title_id;
ViewBag.Titles = new SelectList(db.Titles.ToList(), "title_id", "Titles", vm.title_id);
db.SaveChanges();
return RedirectToAction("Index");
}
Usually I use
db.Entry(member).State = EntityState.Modified;if I have to do other changes beforedb.SaveChanges();memberis already attched to your table. Why do youdb.Members.Attach(member);
update
change
@Html.DropDownListFor(m => m.title_id, ViewBag.Titles)
into
@Html.DropDownListFor(m => m.title_id, (SelectList) ViewBag.Titles)
because ViewBag is a dynamic object
solution2
1 2014-12-04 13:04:57
The problem is the drop down list in the view. You really want to initialize it like this:
@Html.DropDownListFor(m => m.title_id, ViewBag.Titles)
The way you're initializing it now causes the selected value to be passed as a query string parameter - you should see the URL being posted to as ...?Titles=1 for example.
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