如何显示在GridView基于SelectedValue的图像？ [英] How to display an image based on SelectedValue in a GridView?

问题描述

我已经建立了一些后端code检索SQL Server数据库中的图像。我想根据GridView控件的均流选定值我的Web表单上显示此图像。

I have built some back-end code to retrieve an image from a SQL Server database. I want to display this image on my web form based on the currenct selected value of a gridview control.

我有一个名为GetImage.aspx网页，其中有两个查询字符串参数，ENTITYID和的EntityType。 ENTITYID是GridView.SelectedValue和的EntityType简直是T。我的code为GetImage.aspx看起来是这样的：

I have a page called GetImage.aspx which takes two querystring parameters, entityId and entityType. entityId is the GridView.SelectedValue and entityType is simply "T". My code for GetImage.aspx looks like this:

protected void Page_Load (Object server, EventArgs e)
{
    if ((Request.QueryString["entityId"] != null) && (Request.QueryString["entityType"] != null))
    {
        int entityId = int.Parse(Request.QueryString["entityId"]);
        string entityType = Request.QueryString["entityType"];

        DBUtil DB = new DBUtil();

        DataTable dt = DB.GetScreenshot(entityId, entityType);

        if (dt != null)
        {
            Byte[] bytes = (Byte[])dt.Rows[0]["screenshot"];
            Response.Buffer = true;
            Response.Charset = "";
            Response.Cache.SetCacheability(HttpCacheability.NoCache);
            Response.ContentType = dt.Rows[0]["ContentType"].ToString();
            Response.AddHeader("content-disposition", "attachment;filename="+ dt.Rows[0]["fileName"].ToString());
            Response.BinaryWrite(bytes);
            Response.Flush();
            Response.End();
        }
    }
}

什么ASP.NET code，我需要我的呼吁表单上显示这个？

What ASP.NET code do I need to display this on my calling form?

感谢。

修改

我加入这个code到我的形式（我不是要在GridView显示图像，只是我在GridView下表）：

I have added this code to my form (I'm not trying to display the image IN the GridView, just on my form under the GridView):

<img id="tradeScreenshot" runat="server" alt="screenshot" />

和添加了这个$​​ C $ C：

and added this code:

protected void grdTrades_SelectedIndexChanged(object sender, EventArgs e)
{
    string tradeId = grdTrades.SelectedDataKey.Value.ToString();
    tradeScreenshot.Src = "GetImage.aspx?entityId=" + tradeId + "&entityType=T";
}

不显示图像，但是我可以看到正确的ID在数据库服务器上执行，当我选择在GridView项目的存储过程，所以这部分很努力，但图像的显示不。我缺少什么？

The image is not displayed, however I can see the stored procedure being executed on the database server with the correct ID when I select an item in the GridView, so that part is working, but the display of the image isn't. What am I missing?

推荐答案

取决于你显示什么样的GridView和行如何选择。格不具有的SelectedValue - 它已选定的项目，其可具有多个数据键与它

Depends on what you show in gridview, and how rows are selected. Grid doesn't have selectedvalue - it has selected item, which can have multiple data keys with it.

ASP.NET：

<img src="" runat="server" id="selectedimage" />
<asp:GridView OnSelectedIndexChanged="ChangeItem" 
  DataKeyNames="ImageId"
  runat="server" id="MyGrid"></asp:GridView>

C＃：

public void ChangeItem(object o,EventArgs e){
   string ImageId = MyGrid.SelectedDataKey.Value.ToString();
   selectedimage.Src = "GetImage.aspx?entityId="+ImageId+"&entityType=T";
}

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