dzumwalt
asked on
How To Display BLOB Images in a gridview using asp.net VB code
Hi All.
I have seen in EE how to show BLOB images that are stored in the database. The solution showed a c# approach, however I am using asp.net with VB code behind. I tried to convert the c# to vb with no success.
Can anybody give me an example of how to do this?
I have seen in EE how to show BLOB images that are stored in the database. The solution showed a c# approach, however I am using asp.net with VB code behind. I tried to convert the c# to vb with no success.
Can anybody give me an example of how to do this?
Last Comment
prairiedog
Do you have the C# version? I might be able to help you convert it to VB.
ASKER
Sorry for the delay in responding.....
I am having trouble finding the example code that I originally worked from. Here is the code as it stands now.
First ... there one file called Try2_ImageShow.aspx. It is as follows:
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Try2_ImageShow.a
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<img alt="My Picture" src="Try2_ImageSupplier.as
</div>
</form>
</body>
</html>
Then there is a second file called Try2_ImageSupplier.aspx. It is as follows:
Imports System
Imports System.Data
Imports System.Configuration
Imports System.Collections
Imports System.Web
Imports System.Web.Security
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.
Imports System.Web.UI.HtmlControls
Imports System.Data.SqlClient
Imports ODBCTool
Partial Class Try2_ImageSupplier
Inherits System.Web.UI.Page
Dim m_dsPhotos As New DataSet
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim Conn As Odbc.OdbcConnection
Dim da As Odbc.OdbcDataAdapter
Dim drows As DataRow()
Dim bytes() As Byte
Conn = New Odbc.OdbcConnection("DSN=A
da = New Odbc.OdbcDataAdapter()
da.SelectCommand = New Odbc.OdbcCommand("SELECT * FROM InventoryPictures;")
da.SelectCommand.Connectio
da.Fill(m_dsPhotos)
drows = m_dsPhotos.Tables(0).Selec
bytes = drows(0).Item("Picture")
Response.Expires = 0
Response.Buffer = True
Response.Clear()
Response.ContentType = "image/jpg"
Response.BinaryWrite(bytes
Response.End()
End Sub
End Class
I have tried both Response.BinaryWrite(bytes
What am I doing wrong?
I am having trouble finding the example code that I originally worked from. Here is the code as it stands now.
First ... there one file called Try2_ImageShow.aspx. It is as follows:
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Try2_ImageShow.a
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<img alt="My Picture" src="Try2_ImageSupplier.as
</div>
</form>
</body>
</html>
Then there is a second file called Try2_ImageSupplier.aspx. It is as follows:
Imports System
Imports System.Data
Imports System.Configuration
Imports System.Collections
Imports System.Web
Imports System.Web.Security
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.
Imports System.Web.UI.HtmlControls
Imports System.Data.SqlClient
Imports ODBCTool
Partial Class Try2_ImageSupplier
Inherits System.Web.UI.Page
Dim m_dsPhotos As New DataSet
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim Conn As Odbc.OdbcConnection
Dim da As Odbc.OdbcDataAdapter
Dim drows As DataRow()
Dim bytes() As Byte
Conn = New Odbc.OdbcConnection("DSN=A
da = New Odbc.OdbcDataAdapter()
da.SelectCommand = New Odbc.OdbcCommand("SELECT * FROM InventoryPictures;")
da.SelectCommand.Connectio
da.Fill(m_dsPhotos)
drows = m_dsPhotos.Tables(0).Selec
bytes = drows(0).Item("Picture")
Response.Expires = 0
Response.Buffer = True
Response.Clear()
Response.ContentType = "image/jpg"
Response.BinaryWrite(bytes
Response.End()
End Sub
End Class
I have tried both Response.BinaryWrite(bytes
What am I doing wrong?
Does your database store the contenttype or mime type of the image?
ASKER
At this point I am assuming that it is a JPG and so that is why I am saying
Response.ContentType = "image/jpg"
in the code. Is the content type property more than just a string property that contains the above?
Response.ContentType = "image/jpg"
in the code. Is the content type property more than just a string property that contains the above?
1. Do you see a "red cross" or nothing at all when you run the application?
2. Do you use any authentication?
2. Do you use any authentication?
ASKER
No red cross. Blank screen. (Actually ... if I use the "alt", I see the text of the "alt"). I'm not sure what you mean by authentication.
Sorry for being such a novice!
Sorry for being such a novice!
Are you using Forms Authentication or Windows Authentication for your application? In your web.config, there is something like this: <authentication mode="Windows" />.
What happens if you use Image server control, instead of the HTML image tag:
What happens if you use Image server control, instead of the HTML image tag:
<asp:image id="imgMyPicture" runat="server" ImageUrl="Try2_ImageSupplier.aspx"></asp:image>
ASKER
Authentication mode is set to Windows.
I tried the new code that you sent. Same result.
I tried the new code that you sent. Same result.
Let's try this:
1.Comment out these lines:
Response.Expires = 0
Response.Buffer = True
Response.Clear()
2. Use Image Server control as I mentioned earlier, and make sure the ImageUrl is correct.
3. Set Response.ContentType = "image/jpeg"
4. Use Response.OutputStream.Writ
Please report the result. If possible, attach a screen shot.
1.Comment out these lines:
Response.Expires = 0
Response.Buffer = True
Response.Clear()
2. Use Image Server control as I mentioned earlier, and make sure the ImageUrl is correct.
3. Set Response.ContentType = "image/jpeg"
4. Use Response.OutputStream.Writ
Please report the result. If possible, attach a screen shot.
ASKER
No change.
I can verify that the bytes.length is over 300k and so I know it is loading the picture into the byte array.
One question I have is you say to use the "image server" control. If by that you mean:
<asp:image AlternateText="Picture" id="imgMyPicture" runat="server" ImageUrl="Try2_ImageSuppli
Then good. If not, then I cannot find any control that is called "image server". This one is simply called "image" in the toolbox.
Here is the Image_supplier code as it stands now.
Partial Class Try2_ImageSupplier
Inherits System.Web.UI.Page
Dim m_dsPhotos As New DataSet
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim Conn As Odbc.OdbcConnection
Dim da As Odbc.OdbcDataAdapter
Dim drows As DataRow()
Dim bytes() As Byte
Conn = New Odbc.OdbcConnection("DSN=A
da = New Odbc.OdbcDataAdapter()
da.SelectCommand = New Odbc.OdbcCommand("SELECT * FROM InventoryPictures;")
da.SelectCommand.Connectio
da.Fill(m_dsPhotos)
drows = m_dsPhotos.Tables(0).Selec
bytes = drows(0).Item("Picture")
'Response.Expires = 0
'Response.Buffer = True
'Response.Clear()
Response.ContentType = "image/jpeg"
Response.OutputStream.Writ
Response.End()
End Sub
End Class
The web.config contains the following (among other things):
<authentication mode="Windows"/>
I REALLY appreciate you help!
I can verify that the bytes.length is over 300k and so I know it is loading the picture into the byte array.
One question I have is you say to use the "image server" control. If by that you mean:
<asp:image AlternateText="Picture" id="imgMyPicture" runat="server" ImageUrl="Try2_ImageSuppli
Then good. If not, then I cannot find any control that is called "image server". This one is simply called "image" in the toolbox.
Here is the Image_supplier code as it stands now.
Partial Class Try2_ImageSupplier
Inherits System.Web.UI.Page
Dim m_dsPhotos As New DataSet
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim Conn As Odbc.OdbcConnection
Dim da As Odbc.OdbcDataAdapter
Dim drows As DataRow()
Dim bytes() As Byte
Conn = New Odbc.OdbcConnection("DSN=A
da = New Odbc.OdbcDataAdapter()
da.SelectCommand = New Odbc.OdbcCommand("SELECT * FROM InventoryPictures;")
da.SelectCommand.Connectio
da.Fill(m_dsPhotos)
drows = m_dsPhotos.Tables(0).Selec
bytes = drows(0).Item("Picture")
'Response.Expires = 0
'Response.Buffer = True
'Response.Clear()
Response.ContentType = "image/jpeg"
Response.OutputStream.Writ
Response.End()
End Sub
End Class
The web.config contains the following (among other things):
<authentication mode="Windows"/>
I REALLY appreciate you help!
ASKER
I don't know if this makes any difference, but my default browser is firefox.
Yes, I meant Image server control, and sorry about the capitalized "Server" caused confusion.
Can you attach a screen shot of your current page after running the application?
Can you attach a screen shot of your current page after running the application?
ASKER
The code runs ok on my machine. Here is my code and a screen shot (I am using AdventureWorks2000 database). Make sure there is data in your dataset and the selected datarow.
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Image ID="imgPicture" runat="server" AlternateText="Picture" ImageUrl="~/Draw.aspx" /></div>
</form>
</body>
</html>
'Draw.aspx
Partial Class Draw
Inherits System.Web.UI.Page
Dim ds As New DataSet
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim conn As New SqlConnection(ConfigurationManager.ConnectionStrings("AdventureWorks2000ConnectionString").ToString())
Dim sda As New SqlDataAdapter()
sda.SelectCommand = New SqlCommand("SELECT ThumbNailPhoto, LargePhoto FROM ProductPhoto WHERE (ProductPhotoID = 1)", conn)
sda.Fill(ds)
Dim dr As DataRow = ds.Tables(0).Rows(0)
Dim data() As Byte
data = dr("ThumbNailPhoto")
Response.ContentType = "image/jpeg"
Response.OutputStream.Write(data, 0, data.Length)
Response.End()
End Sub
End Class
If you still cannot get the image, then it is likely there is a permission issue on your Sql server. Change your code to the attached code snippet and let me know if you have any exception error.
Try
da.Fill(m_dsPhotos)
drows = m_dsPhotos.Tables(0).Select("InventoryItemUniqueID=3")
bytes = drows(0).Item("Picture")
Response.ContentType = "image/jpeg"
Response.BinaryWrite(bytes)
Response.End()
Catch ex As Exception
End Try
ASKER
OK. I see a disconnect between us. The data is being stored and read from an Access MDB not SQLServer. I have had to covert the code you sent to me as follows:
Dim objDBS As New ADODB.Connection
Dim rst As New ADODB.Recordset
' Create a connection to the access database.
objDBS.Open("Provider=Micr
rst.Open("SELECT Picture FROM InventoryPictures WHERE (InventoryItemUniqueID = 3)", objDBS)
Dim data() As Byte
data = rst("Picture").Value
Response.ContentType = "image/jpeg"
Response.OutputStream.Writ
Response.End()
Still no luck - by the way. I'm trying to see if this is a forefox vs. IE issue and so I have uninstalled firefox completely. NOW THE IDE KEEPS SAYING THAT IT CAN'T FIND FIREFOX AND I CAN'T SEE WHERE TO CHANGE IT TO IE!! I swear - this must be a Monday.
Dim objDBS As New ADODB.Connection
Dim rst As New ADODB.Recordset
' Create a connection to the access database.
objDBS.Open("Provider=Micr
rst.Open("SELECT Picture FROM InventoryPictures WHERE (InventoryItemUniqueID = 3)", objDBS)
Dim data() As Byte
data = rst("Picture").Value
Response.ContentType = "image/jpeg"
Response.OutputStream.Writ
Response.End()
Still no luck - by the way. I'm trying to see if this is a forefox vs. IE issue and so I have uninstalled firefox completely. NOW THE IDE KEEPS SAYING THAT IT CAN'T FIND FIREFOX AND I CAN'T SEE WHERE TO CHANGE IT TO IE!! I swear - this must be a Monday.
ASKER
OK. Figured out how to set the defautl browser for the file. (right click on the file and choose "browse with").
Now that I am using IE, I am now getting an red X.
Now that I am using IE, I am now getting an red X.
ASKER
One final note before I start my weekend,
I have tested this even on the categories table in the Northwind MDB that comes with MSAccess. No joy.
I have tested this even on the categories table in the Northwind MDB that comes with MSAccess. No joy.
Please refer to my comment ID: 22092338. Put your code in a Try/Catch block and report here any exception you encountered.
Also, make sure there is data in your returned dataset/datatable.
Also, make sure there is data in your returned dataset/datatable.
ASKER
Finally, we might be getting somewhere.
I placed the try catch in there and there was apparently a problem with the Response.End(). When it branched to the catch (but hadn't yet executed the code in the catch), at that moment the following showed up in the immediate window:
A first chance exception of type 'System.Threading.ThreadAb
When I attempted to interrogate the EX object, I got the following:
Expression cannot be evaluated at this time.
I placed the following code in the catch section:
Response.Write(ex.Message)
When execiting that line I got the following in the immediate window:
An exception of type 'System.Threading.ThreadAb
Do you think my mscorlib.dll has been hosed somehow?
I placed the try catch in there and there was apparently a problem with the Response.End(). When it branched to the catch (but hadn't yet executed the code in the catch), at that moment the following showed up in the immediate window:
A first chance exception of type 'System.Threading.ThreadAb
When I attempted to interrogate the EX object, I got the following:
Expression cannot be evaluated at this time.
I placed the following code in the catch section:
Response.Write(ex.Message)
When execiting that line I got the following in the immediate window:
An exception of type 'System.Threading.ThreadAb
Do you think my mscorlib.dll has been hosed somehow?
First, I am confused. Why did you have to convert your code? Did the code you provided in your question not work?
Secondly, don't worry about "'System.Threading.ThreadA
Thirdly, can you confirm there is data (in right format) in the row that you just selected.
Secondly, don't worry about "'System.Threading.ThreadA
Thirdly, can you confirm there is data (in right format) in the row that you just selected.
ASKER
OK. I think we are real close now.
The image was originally placed in the database by a VB6 application. In that application I am using ADO to read/write the picture data to/from the database.
I notice that rst.Fields("Picture").Actu
In an effort to prove the third item in your last post, in the asp.net code I took the contents of the database picture field and wrote it to a file. That file turned out to be 301426 bytes in size. Doing a byte by byte comparison of the original file and this one that I wrote out, I notice that there is a ton of nulls (seems like every other character) in the 301426 sized file.
I guess if I can find a way to convert the data (different bit encoding perhaps?) then that might be the key.
The image was originally placed in the database by a VB6 application. In that application I am using ADO to read/write the picture data to/from the database.
I notice that rst.Fields("Picture").Actu
In an effort to prove the third item in your last post, in the asp.net code I took the contents of the database picture field and wrote it to a file. That file turned out to be 301426 bytes in size. Doing a byte by byte comparison of the original file and this one that I wrote out, I notice that there is a ton of nulls (seems like every other character) in the 301426 sized file.
I guess if I can find a way to convert the data (different bit encoding perhaps?) then that might be the key.
If you store the actual size of the image file when saving it to the database, then try change this line:
Response.OutputStream.Writ
Does it make any difference?
Response.OutputStream.Writ
Does it make any difference?
ASKER
No difference.
Take a look at the screenshot. It is an old dos binary comparison program. The upper half of the screen shows the original file, the lower half shows the file that this program is putting out. The bottom line of the upper half of the screen shows (for instance) that there are the characters "Exif", however there are intervening nulls between those characters in the file on the bottom half of the screen. Isn't there some translation method so that I can get the same result in vb.net as vb6?
Snap5.jpg
Take a look at the screenshot. It is an old dos binary comparison program. The upper half of the screen shows the original file, the lower half shows the file that this program is putting out. The bottom line of the upper half of the screen shows (for instance) that there are the characters "Exif", however there are intervening nulls between those characters in the file on the bottom half of the screen. Isn't there some translation method so that I can get the same result in vb.net as vb6?
Snap5.jpg
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ASKER
I will do exactly that. For future readers of this thread, the new question ID is 23601647
prairiedog ... I appreciate you hanging in there with me on this. Even though the issue isn't fully resolved, you have definitely helped me with narrowing down where the problem. I will award the points for this thread to you.
Thanks!
prairiedog ... I appreciate you hanging in there with me on this. Even though the issue isn't fully resolved, you have definitely helped me with narrowing down where the problem. I will award the points for this thread to you.
Thanks!
Hi dzumwalt,
You're very welcome. I learned a lot during the whole process.
I hope once you get the answer for your new question (https://www.experts-exchange.com/questions/23601647/How-vb-net-can-read-binary-BLOB-data-from-MSAccess-originally-saved-by-vb6-AppendChunk.html), you can come back to this question to test the code to see if it will work then.
You're very welcome. I learned a lot during the whole process.
I hope once you get the answer for your new question (https://www.experts-exchange.com/questions/23601647/How-vb-net-can-read-binary-BLOB-data-from-MSAccess-originally-saved-by-vb6-AppendChunk.html), you can come back to this question to test the code to see if it will work then.
ASKER
We achieved success for this on question #23601647. (https://www.experts-exchange.com/questions/23601647/How-vb-net-can-read-binary-BLOB-data-from-MSAccess-originally-saved-by-vb6-AppendChunk.html)
Congrats!
Now, are you able to display the image with the code I provided here?
Now, are you able to display the image with the code I provided here?
ASKER
Yes. The final code is as follows.
Imports System.Data.OleDb
Imports System.IO
Imports System.Xml.Serialization
Imports System.Drawing.Imaging
Imports System.Text
Partial Class Draw
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim dbsMain As New ADODB.Connection
Dim rst As New ADODB.Recordset
Dim MyData() As Byte
' Create a connection to the database.
dbsMain.Open("DSN=AuctionR
' Fill the recordset with a the sought after data.
rst.Open("SELECT * FROM InventoryPictures WHERE InventoryItemUniqueID=3;",
' Assign the data to a byte var.
MyData = rst("Picture").Value
' Perform tests.
Response.ContentType = "image/jpeg"
Response.OutputStream.Writ
' Close out objects.
rst.Close()
dbsMain.Close()
End Sub
End Class
Imports System.Data.OleDb
Imports System.IO
Imports System.Xml.Serialization
Imports System.Drawing.Imaging
Imports System.Text
Partial Class Draw
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim dbsMain As New ADODB.Connection
Dim rst As New ADODB.Recordset
Dim MyData() As Byte
' Create a connection to the database.
dbsMain.Open("DSN=AuctionR
' Fill the recordset with a the sought after data.
rst.Open("SELECT * FROM InventoryPictures WHERE InventoryItemUniqueID=3;",
' Assign the data to a byte var.
MyData = rst("Picture").Value
' Perform tests.
Response.ContentType = "image/jpeg"
Response.OutputStream.Writ
' Close out objects.
rst.Close()
dbsMain.Close()
End Sub
End Class
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