当我尝试从数据库中获取图像并绑定到datgridview时，我收到错误 [英] I have getting error when I am trying fetch images from database and bind to datgridview

问题描述

实际上我首先尝试在数据库中保存图像，这部分我已经完成了，但是当我尝试从数据库中获取图像并将该图像绑定到datagridview时，这部分正在生成错误，如何解决这个问题，请帮助



我尝试过：



con.Open（）;

SqlDataReader dr = cmd.ExecuteReader（）;

if（dr.HasRows == true）

{

while（dr.Read（））

{

byte [] bArray =（byte []）dr [image ;;

MemoryStream ms = new MemoryStream（bArray）;

Image returnImage = Image.FromStream（ms）;





}

}

con.Close（）;







byte [] bArray =（byte []）dr [image];此行显示错误

无法将System.String类型的对象强制转换为System.Byte []。

Actually first of all i am trying to save image in database , this part i have already done ,
but when i trying to fetch image from database and bind that image to datagridview this part is generating error, how to solve this problem, pls help

What I have tried:

con.Open();
SqlDataReader dr = cmd.ExecuteReader();
if (dr.HasRows == true)
{
while (dr.Read())
{
byte[] bArray = (byte[])dr["image"];
MemoryStream ms = new MemoryStream(bArray);
Image returnImage = Image.FromStream(ms);


}
}
con.Close();



byte[] bArray = (byte[])dr["image"]; this line show error
Unable to cast object of type 'System.String' to type 'System.Byte[]'.

推荐答案

错误说的是你可以将字符串转换为字节数组 - 这意味着数据库中的列是VARCHAR或NVARCHAR字段而不是VARBINARY或BLOB

这意味着其中一个两件事：

1）你根本没有存储实际的图像数据。

或

2）你把它存储为BASE64字符串或类似字符串。



如果没有您用来保存它的代码，我们无法分辨哪个 - 但是从上面的代码中，我怀疑第一个和你保存了字符串连接的图像。

看看这个：为什么我得到参数无效。我从数据库中读取图像时出现异常？ [ ^ ]它会告诉您最有可能出现的问题，以及如何绕过它。

What the error says is that you can;t convert a string to a byte array - which means that the column in your database is a VARCHAR or NVARCHAR field instead of a VARBINARY or BLOB
Which means one of two things:
1) You haven't stored the actual image data at all.
Or
2) You've stored it as a BASE64 string or similar.

Without the code you used to save it, we can't tell which - but from your code above, I'd suspect the first and that you "saved" the image by string concatenation.
Have a look at this: Why do I get a "Parameter is not valid." exception when I read an image from my database?[^] It shows you what the problem most likely is, and how to get round it.

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