使用Linq从数据库检索图像到SQL [英] Retrieving an image from database with Linq to SQL

问题描述

在数据库中，我以图像"数据类型存储了图像，并显示为二进制代码. 现在，我想从一列中检索所有图像，并使用C#在asp.net页面上显示它们.

In my database I have stored images in the "image" data type, showing up as a binary code. I now want to retrieve all images from one column and diplay them on a asp.net page with C#.

databaseDataContext db = new databaseDataContext();

    var images = from Picture p in db.Pictures
                 select p.pictureThumb;

然后我用这个:

    foreach (Picture p in images)
    {
        galleryImages.Controls.Add(p);
    }

但这不起作用，因为二进制文件无法转换为图片.我已经对此进行了Google搜索，发现我必须转换为Byte，然后再转换为图像?我找不到有关如何执行此操作的示例.

But that doesn't work because Binary can't be converted to Picture. I have Googled this and found that I have to cast to Byte and then to image? I can't find examples on how to do that though.

推荐答案

这应该做到:

databaseDataContext db = new databaseDataContext();

var images = from p in db.Pictures
             select Image.FromStream(new MemoryStream(p.pictureThumb.ToArray());
foreach (Image image in images)
{
    galleryImages.Controls.Add(image);
}

请注意，Image.FromStream拥有流的所有权-无论如何，它只是一个MemoryStream，但出于各种原因，请确保处置该图像.

Note that Image.FromStream takes ownership of the stream - it's only a MemoryStream anyway, but do make sure that you dispose of the image, for various reasons.

嗯...我还没有意识到这是针对ASP.NET的.这使事情变得更加艰难-因为HTML将包含URL，然后您将需要稍后才能获取数据.

Ah... I hadn't realised that this was for ASP.NET. That makes things harder - because the HTML is going to contain URLs, and then you'll need to be able to fetch the data later.

图片是否具有某种ID?如果是这样，则获取该数据而不是实际数据，然后设置一个URL，该URL可以根据ID提供任何缩略图(通过从数据库中获取缩略图并仅使用适当的内容类型对其进行提供).

Does a picture have an ID of some kind? If so, fetch that instead of the actual data, and then set up a URL which is able to serve any thumbnail based on the ID (by fetching it from the database and just serving it with an appropriate content type).

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