c# - 尝试在没有 Entity Framework 的情况下使用表单发布——我放弃了，但会保持打开状态，以防它帮助某人......在某个地方

Question

在尝试让基本 CRUD 在我的 Web 应用程序中工作时，我遇到了一些问题。首先，这是我连接到数据库的方式:

public class DatabaseController : Controller
{
    protected MySqlConnection conn;

    public DatabaseController()
    {
        //Vul hier de juiste gegevens in!!
        conn = new MySqlConnection("Server=localhost;Database=db;Uid=pw;Pwd=pw;");
    }
}

这就是我最初加载行的方式:

 public Klant getAll(string naam)
    {
        MySqlTransaction trans = null;
        Klant klanten = new Klant();

        conn.Open();
        trans = conn.BeginTransaction();
        try
        {
            string selectQuery = @"select * from klant;";

            MySqlCommand cmd = new MySqlCommand(selectQuery, conn);
            //MySqlParameter naamParam = new MySqlParameter("@naam", MySqlDbType.VarChar);
            //naamParam.Value = "%" + naam + "%";
            //cmd.Parameters.Add(naamParam);
            cmd.Prepare();


            MySqlDataReader dataReader = cmd.ExecuteReader();
            while (dataReader.Read())
            {
                int IdKlant = dataReader.GetInt32("idklant");
                String Naam = dataReader.GetString("naam");
                String Woonplaats = dataReader.GetString("woonplaats");
                DateTime Geboortedatum = dataReader.GetDateTime("geboortedatum");
                String Geslacht = dataReader.GetString("geslacht");
                String Beschrijving = dataReader.GetString("beschrijving");


                klanten.idklant = IdKlant;
                klanten.naam = Naam;
                klanten.woonplaats = Woonplaats;
                klanten.geboortedatum = Geboortedatum;
                klanten.geslacht = Geslacht;
                klanten.beschrijving = Beschrijving;



            }
        }

        catch (Exception e)
        {
            throw new Exception("Product niet toegevoegd: " + e);
        }

        finally
        {
            conn.Close();
        }

        return klanten;
    }

这就是我在 View 中加载它们的方式:

@{ if (@Model == null)
 {
    <div>geen producten gevonden</div>
 }
 else
 {
    <div></div><br>
     foreach (Klant kl in Model)
     {

        <tr>
            <td>
                @Html.DisplayFor(modelItem => kl.idklant)
            </td>
            <td>
                @Html.DisplayFor(modelItem => kl.naam)
            </td>

            <td>
                @Html.ActionLink("Details", "ShowKlant", new { id = kl.idklant }) |
                @Html.ActionLink("Edit", "ShowKlant", new { id = kl.idklant }) |
                @Html.ActionLink("Delete", "ShowKlant", new { id = kl.idklant })<br /><br />
            </td>
        </tr>

     }
 }
}

读取操作工作正常(在某种程度上)。

我能够从数据库加载所有行，每行都有一个详细信息/编辑/删除/选项，该选项使用每个相应行的正确 ID。

如果我点击具有 id3 的客户，则会加载此链接:

http://localhost:51596/Home/ShowKlant/3

即使在 actionResult 之上使用 [HttpPost] 重载，如下所示:

        public ActionResult ShowKlant(int? idklant)
    {
        Klant k = new Klant();
        KlantDBController sc = new KlantDBController();
        k = sc.getById(idklant);
        return View(k);
    }

    [HttpPost]
    public ActionResult ShowKlant(Klant klant)
    {
        return View(klant);
    }

这些字段没有被填充。

这是 View 在代码中的样子:

    @using (Html.BeginForm())
{
    @Html.ValidationSummary(true)
    <fieldset>
        <legend>Movie</legend>
        <div class="editor-label">
            @Html.LabelFor(model => model.idklant)
        </div>
        <div class="editor-label">
            @Html.EditorFor(model => model.idklant)
        </div>
        <div class="editor-label">
            @Html.LabelFor(model => model.naam)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.naam)
            @Html.ValidationMessageFor(model => model.naam)
        </div>

        <div class="editor-label">
            @Html.LabelFor(model => model.woonplaats)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.woonplaats)
            @Html.ValidationMessageFor(model => model.woonplaats)
        </div>

        <div class="editor-label">
            @Html.LabelFor(model => model.geboortedatum)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.geboortedatum)
            @Html.ValidationMessageFor(model => model.geboortedatum)
        </div>

        <div class="editor-label">
            @Html.LabelFor(model => model.geslacht)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.geslacht)
            @Html.ValidationMessageFor(model => model.geslacht)
        </div>

        <div class="editor-label">
            @Html.LabelFor(model => model.beschrijving)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.beschrijving)
            @Html.ValidationMessageFor(model => model.beschrijving)
        </div>

        <p>
            <input type="submit" value="Save" />
        </p>
    </fieldset>
}

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

我可能遗漏了一些小东西......但我认为问题可能在于我如何加载详细信息页面的数据......我只是看不到它:/

我的 getById 代码本质上与 getAll 相同。

获取ID代码是这个

 string selectQuery = @"select * from klant where idklant = @idklant;";

这就是和我平常的SQL不同的地方。

如果我这样做:

 string selectQuery = @"select * from klant;";

它填充数据，但仅填充数据库中的最后一行，无论我使用哪个客户，它都会返回/填充最后一行。

一切:

不愉快的结果:

Answer 1

您的问题是 @idklant 从未设置过值。

您有一个名为 getById(int idklant) 的函数

MySqlCommand cmd = new MySqlCommand(selectQuery, conn); 
MySqlParameter idklantParam = new MySqlParameter("@idklant", MySqlDbType.Int32); 
cmd.Parameters.Add(idklantParam);

并且您从未设置参数的值，仅设置类型。在 cmd.Parameters.Add 之前你应该有

idklantParam.value = idklant; // or whatever your parameter name is in your method