C#WPF从SQL Server数据库检索图像，字节到图像 [英] C# WPF Retrieve Image from SQL Server database, byte to image

问题描述

所以我有这些代码可以获取用户信息.

So I have these codes that will get me the user information.

注意:注释行是我已经尝试过的内容.

NOTE: the commented lines are the stuff that I have already tried.

代码:

    public UserInfo GetUserCredentials(string usernameParameter, string passwordParameter)
    {
        UserInfo getInfo = new UserInfo();

        try
        {
            accessToDatabase.OpeningDatabase();
            String query = "SELECT * FROM Users where Username=@Username AND Password=@Password";
            SqlCommand sqlCmd = accessToDatabase.Command(query);

            sqlCmd.CommandType = CommandType.Text;
            sqlCmd.Parameters.AddWithValue("@Username", usernameParameter);
            sqlCmd.Parameters.AddWithValue("@Password", passwordParameter);
            SqlDataReader oReader = sqlCmd.ExecuteReader();

            byte[] pictureIdByte;
            Image pictureIdImg = null;

            while (oReader.Read())
            {
                getInfo.Username = oReader["Username"].ToString();
                getInfo.Password = oReader["Password"].ToString();
                getInfo.Role = oReader["Role"].ToString();
                getInfo.Firstname = oReader["Firstname"].ToString();
                getInfo.Lastname = oReader["Lastname"].ToString();
                getInfo.Status = Convert.ToInt32(oReader["Status"]);
                getInfo.Gender = oReader["Gender"].ToString();
                getInfo.Birthday = oReader["Birthday"].ToString();
                getInfo.Email = oReader["Email"].ToString();
                getInfo.Address = oReader["Address"].ToString();
                getInfo.City = oReader["City"].ToString();
                getInfo.Country = oReader["Country"].ToString();
                getInfo.Mobilenumber = oReader["Mobile"].ToString();

                pictureIdByte = (byte[])(oReader["PictureID"]);

                if (pictureIdByte == null)
                {
                    getInfo.PictureID = pictureIdImg;
                }
                else
                {
                    //MemoryStream stream = new MemoryStream(pictureIdByte);
                    //getInfo.PictureID.Source = BitmapFrame.Create(stream, BitmapCreateOptions.None, BitmapCacheOption.OnLoad);

                    //var pictureIdVar = new BitmapImage();
                    //using (var memStream = new MemoryStream(pictureIdByte))
                    //{
                    //    memStream.Position = 0;
                    //    pictureIdVar.BeginInit();
                    //    pictureIdVar.CreateOptions = BitmapCreateOptions.PreservePixelFormat;
                    //    pictureIdVar.CacheOption = BitmapCacheOption.OnLoad;
                    //    pictureIdVar.UriSource = null;
                    //    pictureIdVar.StreamSource = memStream;
                    //    pictureIdVar.EndInit();
                    //}
                    //pictureIdVar.Freeze();
                    //getInfo.PictureID.Source = pictureIdVar;
                }
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
        finally
        {
            accessToDatabase.ClosingDataBase();
        }
        return getInfo;
    }

然后我在这个主窗口中有一个图像，该图像是我从xaml设计中拖放下来的.并使用后面的代码，我试图像这样设置源，但是每当我尝试登录时，它都会给我一个错误:

AND I have this main window where it has an image which I dropped and drag from the xaml design. And using the code behind, I tried setting the source like this but whenever I am trying to log-in it is giving me an error of:

System.NullReferenceException:'对象引用未设置为对象的实例.'

System.NullReferenceException: 'Object reference not set to an instance of an object.'

MyThesisProject.Model.UserInfo.PictureID.get 返回null.

以下是xaml主窗口中的代码:

Here is the code behind of the main window xaml:

public partial class MainWindow : Window
{
    public MainWindow(UserInfo userLoginDetails)
    {
        InitializeComponent();
        imgTest.Source = userLoginDetails.PictureID.Source;
    }
}

我不知道哪里出了问题，我尝试使用带注释的行，但仍然出现null错误.

I do not know where did I go wrong, I tried using the commented lines but still the same error of null.

推荐答案

您的UserInfo类中不应包含 Image 元素.

You should not have an Image element in your UserInfo class.

将 PictureID 属性的类型更改为ImageSource

Change the type of the PictureID property to ImageSource

public class UserInfo
{
    ...
    public ImageSource PictureID { get; set; } 
    ...
}

并按如下所示设置其值:

and set its value like this:

if (pictureIdByte != null)
{
    using (var stream = new MemoryStream(pictureIdByte))
    {
        getInfo.PictureID = BitmapFrame.Create(stream,
                                BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
    }
}

在您的MainWindow构造函数中，如下设置图像的源:

In your MainWindow constructor, set the Image's Source like this:

imgTest.Source = userLoginDetails.PictureID;

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