错误“发生了参照完整性约束冲突”

Question

Can you please help me with my code?

I have 2 models:

public class Author
{
    public int Id { get; set; }
    public string AuthorName { get; set; }

    public IEnumerable<Book> Books { get; set; }
}

public class Book
{
    public int Id { get; set; }
    public string Title { get; set; }
    public int YearPublish { get; set; }
    public int Price { get; set; }

    public int? AuthorId { get; set; } //FK
    public Author Author { get; set; } //navigation property
}

And trying to make an Edit function. Controller code:

// GET: Books/Edit/5       
public ActionResult Edit(int? id)
{
    if (id == null)
    {
        return HttpNotFound();
    }
    Book bookEdit = dbBooks.Books.Include(a => a.Author).Where(a => a.AuthorId == id).Single();
    return View(bookEdit);
}

// POST: Books/Edit/5
[HttpPost]
public ActionResult Edit(Book book)
{
    if (ModelState.IsValid)
    {
        // TODO: Add update logic here
        //book.Author = null; //AuthorName cant be edited
        dbBooks.Entry(book).State = EntityState.Modified;
        dbBooks.SaveChanges();
        return RedirectToAction("Index");
    }

    return View(book);
}

And my View:

<div class="form-horizontal">
    <h4>Book</h4>
    <hr />
    @Html.ValidationSummary(true, "", new { @class = "text-danger" })
    @Html.HiddenFor(model => model.Id)

    <div class="form-group">
        @Html.LabelFor(model => model.Author.AuthorName, "AuthorName", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Author.AuthorName, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Author.AuthorName, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Title, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Title, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Title, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.YearPublish, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.YearPublish, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.YearPublish, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Price, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.Price, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.Price, "", new { @class = "text-danger" })
        </div>
    </div>        

    <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
            <input type="submit" value="Save" class="btn btn-default" />
        </div>
    </div>
</div>

And when i try just to click Save button (even if i dont do any changes) an error occured: A referential integrity constraint violation occurred: The property value(s) of 'Author.Id' on one end of a relationship do not match the property value(s) of 'Book.AuthorId' on the other end. Error is in dbBooks.Entry(book).State = EntityState.Modified;

If I try to add book.Author = null; it is logically than my AuthorNames` start to disappear...

Also I was trying to put something in Html.HiddenFor, but maybe I was doing something wrong, but nothing changed.

Answer 1

Well, you couldn't modify AuthorName in Book's editor view. You need another view for Author to modify it.

book.Author - cannot be null , becouse its navigation property and can only be like readonly mode. So just remove editormodel for author.authorname

Modified books list:

Book bookEdit = dbBooks.Books.ToList().Where(a => a.Id == id).SingleOrDefault();

Answer 2

Look what you need to do, i got it now. You just need selectList of all Author's and in a view name will be auto selected on AuthorId book's field. Make new one form-group with

<div class="form-group">
    @Html.LabelFor(model => model.AuthorId, htmlAttributes: new { @class = "control-label col-md-2" })
    <div class="col-md-10">
           @(Html.DropDownListFor(p => p.AuthorId, (SelectList)ViewBag.Authors, new { @class = "form-control" }))
        @Html.ValidationMessageFor(model => model.AuthorId, "", new { @class = "text-danger" })
    </div>
</div>

And in Your Edit action:

// GET: Books/Edit/5       
public ActionResult Edit(int? id)
{
    if (id == null)
    {
        return HttpNotFound();
    }
    Book bookEdit = dbBooks.Books.Where(a => a.Id == id).Single();
    // UPDATED
    var list = dbBooks.Books.Select(x => new  { ID = x.Id, AuthorName = x.AuthorName });
    ViewBag.Authors = new SelectList(list, "Id", "AuthorName");
    // UPDATED
    return View(bookEdit);
}

Answer 3

Again many thanks!

But using DropDownList dont allow me to edit Author`s name.. But that solution is rly good.

I need to edit all 4 fields like name, title, year and price.

I try to make something like composite model:

public class BookAuthorCompositeModel
{
    public Author author { get; set; }
    public Book book { get; set; }
}

Change my get method:

// GET: Books/Edit/5       
    public ActionResult Edit(int? id)
    {
        if (id == null)
        {
            return HttpNotFound();
        }
        var compModel = new BookAuthorCompositeModel();
        compModel.book = dbBooks.Books.ToList().Where(a => a.Id == id).SingleOrDefault();
        compModel.author = dbBooks.Authors.ToList().Where(x => x.Id == id).SingleOrDefault();


        return View(bookEdit);
    }

and it displays all I need (i tap "edit" and see information about name, title, year and price).

My view is:

    @model BookStorage.Models.BookAuthorCompositeModel

@{
    ViewBag.Title = "Edit";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Edit</h2>


@using (Html.BeginForm())
{
    @Html.AntiForgeryToken()

    <div class="form-horizontal">
        <h4>Book</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        @Html.HiddenFor(model => model.book.Id)

        <div class="form-group">
            @Html.LabelFor(model => model.author.AuthorName, "AuthorName", htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.author.AuthorName, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.author.AuthorName, "", new { @class = "text-danger" })
            </div>
        </div>
        <div class="form-group">
            @Html.LabelFor(model => model.book.Title, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.book.Title, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.book.Title, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.book.YearPublish, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.book.YearPublish, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.book.YearPublish, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.book.Price, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.book.Price, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.book.Price, "", new { @class = "text-danger" })
            </div>
        </div>


        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Save" class="btn btn-default" />
            </div>
        </div>
    </div>
}

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

@section Scripts {
    @Scripts.Render("~/bundles/jqueryval")
}

but something wrong is in Post method:

[HttpPost]
    public ActionResult Edit(Book book)
    {
        if (ModelState.IsValid)
        {
            dbBooks.Entry(BAmodel.book).State = EntityState.Modified;
            dbBooks.Entry(BAmodel.author).State = EntityState.Modified;

            dbBooks.SaveChanges();
            return RedirectToAction("Index");
        }
        return View(book);
    }

dbBooks.SaveChanges(); leads to error.. I think using this kind of ViewModel helps to edit all rows, but it doesnt sade data to DB...

Maybe you could help with this please?