Question

我目前有一个编辑页面，我有一张发票。这是一张保存为二进制值的图片。

当我想编辑发票时，我希望图片保持不变，但是当我按下保存时，它会删除图像并将行更新为空。

它可能与我的编辑方法有关吗？

这是我的剃刀页面的一部分：

@{
    ViewBag.Title = "Edit";
    if (Model.PictureOfInvoice != null)
    {
        var base64 = Convert.ToBase64String(Model.PictureOfInvoice);
        var imgsrc = string.Format("data:image/jpg;base64,{0}", base64);
        <img src="@imgsrc" style="max-width:500px;max-height:500px" align="right" />
    }
}

<h2>Details of Invoice</h2>

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

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

有没有办法不更新？

修改

public ActionResult Edit(int? id)
{
    if (id == null)
    {
        return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
    }

    Invoice invoice = db.Invoices.Find(id);
    if (invoice == null)
    {
        return HttpNotFound();
    }

    ViewBag.ChurchId = new SelectList(db.Churches, "ChurchId", "Name", invoice.ChurchId);
    return View(invoice);
}

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit([Bind(Include = "InvoiceId,Company,Description,Amount,ChurchId")] Invoice invoice)
{
    if (ModelState.IsValid)
    {
        db.Entry(invoice).State = EntityState.Modified;
        db.SaveChanges();
        return RedirectToAction("Index");
    }

    ViewBag.ChurchId = new SelectList(db.Churches, "ChurchId", "Name", invoice.ChurchId);
    return View(invoice);
}

我的模特：

public class Invoice
{
    [Key]
    public int InvoiceId { get; set; }

    public string Company { get; set; }

    public string Description { get; set; }

    public decimal Amount { get; set; }

    public byte[] PictureOfInvoice { get; set; }

    public string ImageFileName { get; set; }

    [ForeignKey("Church")]
    public int ChurchId { get; set; }

    public virtual Church Church { get; set; }

    public virtual Administration Admins { get; set; }
}

Answer 1

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit([Bind(Include = "InvoiceId,Company,Description,Amount,ChurchId")] Invoice invoice)
{
    if (ModelState.IsValid)
    {
        Invoice oldInvoice = db.Invoices.Find(id);
        oldInvoice.Amount = invoice.Amount;
        // repeated for all of the properties (but not the image)

        db.SaveChanges();
        return RedirectToAction("Index");
    }
    ViewBag.ChurchId = new SelectList(db.Churches, "ChurchId", "Name", invoice.ChurchId);
    return View(invoice);
}

关键是使用db.Invoices.Find从数据库中获取现有项目。这样就不会丢失现有属性（如图像）。

如何在编辑剃刀页面中仅保存某些值

1 个答案: