I'm currently patching an asp.net program where I need to be able to send an image to an SQL Server 2005 DB. It works fine when I use the asp:fileupload control, but the trick is that when the user deletes the image, I'm supposed to replace it with an image from the server saying "empty", in code-behind.
I know how to open, use and save text files in vb, but I can't find any information anywhere on how to open an image / binary file in a similar manner so that I can use it as an sql-parameter on the update query.
Below is an example of how easy it is to use a file from the fileupload control.
Dim t_id As Integer = Convert.ToInt32(Request.QueryString("id"))
open()
Dim picture As New SqlParameter("#picture", pictureFileUpload.FileBytes)
Dim id As New SqlParameter("#id", t_id)
myCommand = New SqlCommand("spChangeImage")
myCommand.CommandType = CommandType.StoredProcedure
myCommand.Connection = conn
myCommand.Parameters.Add(picture)
myCommand.Parameters.Add(id)
myCommand.ExecuteNonQuery()
close()
Now I need a way to open an image file and set it as a parameter in a similar manner, but I've no clue as to how to go about doing that. All the search results are focused on opening and viewing an image in html, I just need the binary to use it in the query. I'm trying to use binaryreader but even then I've no idea how to actually map the file to begin with.
Thanks in advance for any help!
Personally, I wouldn't store this image in the database when the user deletes their value. I would set the column to null. When writing the image I would detect if the column is null, then read the file and write it to the response. If you do this, then you won't need to accumulate anything into a local buffer, you can just write each buffer to the response as it is read. You can use FileInfo.Length to determine the content length of the response.
If you insist on putting the image in the DB, you can also use FileInfo.Length to determine the size of buffer you need to hold the image. Use your BinaryReader to read this length of bytes into the buffer. The buffer then becomes your parameter to the SQL command.
this might help.
Related
Long time lurker first time poster. Working with .Net / Linq for just a few years so I'm sure I'm missing something here. After countless hours of research I need help.
I based my code on a suggestion from https:http://damieng.com/blog/2010/01/11/linq-to-sql-tips-and-tricks-3
The following code currently saves a chosen file (pdf, doc, png, etc) which is stored in an sql database to the C:\temp. Works great. I want to take it one step further. Instead of saving it automatically to the c:\temp can I have the browser prompt so they can save it to their desired location.
{
var getFile = new myDataClass();
//retrieve attachment id from selected row
int attachmentId = Convert.ToInt32((this.gvAttachments.SelectedRow.Cells[1].Text));
//retrieve attachment information from dataclass (sql attachment table)
var results = from file in getFile.AttachmentsContents
where file.Attachment_Id == attachmentId
select file;
string writePath = #"c:\temp";
var myFile = results.First();
File.WriteAllBytes(Path.Combine(writePath, myFile.attach_Name), myFile.attach_Data.ToArray());
}
So instead of using File.WriteAllBytes can I instead take the data returned from my linq Query (myFile) and pass it into something that would prompt for the user to save the file instead?). Can this returned object be used with response.transmitfile? Thanks so much.
Just use the BinaryWrite(myFile.attach_Data.ToArray()) method to send the data since it is already in memory.
But first set headers appropriately, for example:
"Content-Disposition", "attachment; filename="+myFile.attach_Name
"Content-Type", "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
Content-type guides the receiving system on how it should handle the file. Here are more MS Office content types. If they are known at the point the data is stored, the content-type should be stored, too.
Also, since the file content is the only data you want in the response, call Clear before and End after BinaryWrite.
I have a customer that is asking to be able to retrieve an image from a Sql Server Db and turn around and save it to a directory on his computer. He wants to be able to do this via a asp.net web page. I am able to retrieve the image from the image as a byte array but have no idea how to take that image and save it to the directory as a file. Anyone have any ideas on how to do this? Thanks.
You can try with Save Method
MemoryStream memoryStream = new MemoryStream((byte[])YourDataTable.Rows[0]["ImageData"]);
Picturebox picturebox = new Picturebox();
picturebox.Image = Image.FromStream(memoryStream);
picturebox.Image.Save("...YourPath", System.Drawing.Imaging.ImageFormat.Jpeg)
I have Stored my resume(word document) in my database.and i just want to show that resume in txt format to user. how can i show it to user?
I'm not that good in ASP.NET, but check the links below. Maybe it's not a solution, you want, but can be useful.
Save-Read-Image-Database
There isn't that much of difference, depending on what type to you use for your resume, a varchar or maybe varbinary.
How to Create a text file in ASP .NET
Reading and Writing Text Files with the .NET Framework
Tutorials on how to read/write a file in asp.net.
Good Luck!
UPDATE:
So if it's a varbinary type, you can read as it was shown in first link. I'll paste a part with some changes.
connection.Open();
SqlCommand command1 = new SqlCommand("select <resume_content> from <resume_table> where id = #id", connection);
SqlParameter myparam = command1.Parameters.Add("#id", SqlDbType.Int);
myparam.Value = <your_value>
byte[] resume = (byte[])command1.ExecuteScalar();
MemoryStream str = new MemoryStream();
str.Write(resume, 0, resume.Length);
After that, just save the Stream to a file. Here's the link
Save a Stream to a File
UPDATE 2:
It's because you SELECT two columns. It takes FileName as the value for byte[]. For two columns you'd need to use ExecuteReader instead of ExecuteScalar.
Check this link
http://www.developerfusion.com/article/4278/using-adonet-with-sql-server/2/
Probably best to direct the user to download the document directly, and they can open it themselves.
I have a sql server database that returns byte for the image. If I use the tableadapter wizard and set it to my stored procedure and preview data, it pulls back an image. It automatically turns it into an image in the preview data. I don't see it as a string of Ints or anything.
How can I display it on my asp.net webpage with a gridview and objectdatasource?
I have searched and foudn where the imagefield can point to a url on another page that does the byte transformation but I'm not sure it's the best. I found another way that creates a temp file.
Just trying to see the best way to do it.
edit - I am trying not to use a temp file. If I cannot use a gridview a regular image field is ok.
asp.net 2.0, c#.
Thank you for any help.
edit
ended up with:
protected void Page_Load(object sender, EventArgs e)
{
string id = Request["id"];
string connstr = "DSN=myserver";
OdbcConnection conn = new OdbcConnection(connstr);
OdbcCommand cmd = new OdbcCommand("{call mySP (?)}", conn);
cmd.CommandType = CommandType.StoredProcedure;
// Add the input parameter and set its properties.
OdbcParameter parameter = new OdbcParameter();
parameter.ParameterName = "#MyParam";
parameter.OdbcType = OdbcType.VarChar;
parameter.Direction = ParameterDirection.Input;
parameter.Value = id;
// Add the parameter to the Parameters collection.
cmd.Parameters.Add(parameter);
conn.Open();
OdbcDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
byte[] buffer = (byte[])dr[0];
Response.ContentType = "image/jpg";
Response.BinaryWrite(buffer);
Response.Flush();
}
}
and this on the calling page:
<asp:Image ID="Image1" ImageAlign="Middle" ImageUrl="show.aspx?id=123" Runat="server" />
Two options:
Create a temp file - The problem with this approach is that you have to create the file, which means your web must have write access to a directory which is not a great thing. You also need to have a way to clean up the images.
Serve it from another URL - This is my preferred method, as you have no disk access required. A simple http handler (ashx) is a great method to serve up the image.
Edit
If you need session state in the ashx, check out: Asp.net System.Web.HttpContext.Current.Session null in global.asax.
Edit
Couple more thoughts. There are some cases where using a temp file might be better. For example if your images are requested frequently by a lot of users. Then storing the images on the disk would make sense, since you could write the file once, this does increase the maintance complexity but depending on traffic it might be worth it since this would let you avoid calling back into the .net stack and leverage IIS caching of static content.
I wrote the SqlReader plugin for open-source ImageResizing.Net library to allow you to serve and display images from a SQL database in the most performance-optimal way.
Even if you don't need to do any image processing whatsoever, it's still (a) the easiest, and (b) the most efficient way to do it. You can combine it with disk caching (which provides automatic cleanup) to get the best performance that is possible.
Installation is easy - 2 nuget commands, or copy & paste into Web.Config, your pick.
If you need help, support is free and fast.
The sample code you added is good but you should move it to a .ashx file which is meant for such things.
Here is some example code on how to do this.
I save my images into my SQL Server Database with ASP.NET(2.0).
(imageData -> image) (imageType -> varchar) (imageLength -> bigint)
Thus the imageData will be "Binary data" and the imageType will be like "image/gif" and the imageLength will be like "6458".......
Is it possible to get the image HEIGHT and WIDTH from my VB.NET code inside my ASP.NET?
I want to make my picture box on my web form the size of the actual image that is saved in my database.
Regards
Etienne
Assuming you have the data in a stream:
System.Drawing.Image.FromStream(yourStream).Height
You are probally better doing this when you save the image to the DB, as I'm sure that loading the image object isn't going to be cheap.
Edit
If we take this to email then the next guy with this issue won't have a record of our solution. Let's keep it in the forum for now.
Just so we know, I am a C# developer so I'm not going to try and remember vb.net syntax if this is an issue and you need help converting let me know.
You have an IDataReader I'm assuming which is pulling an Image or binary varbinary etc field from your DB. You need to load it into an object which derives from System.IO.Stream. For our purposes a MemoryStream is the perfect choice as it doesn't require a backing store such as a disk.
System.IO.MemoryStream yourStream = new System.IO.MemoryStream(dr["imgLength"] as byte[]);
System.Drawing.Image yourImage=System.Drawing.Image.FromStream(yourStream);
yourImage.Height;
yourImage.width
I would save the height and width of the image in separate columns when you save the image to the database intially. Then when you do your select statement to read the image out of the database, you can also access the height and width fields from the database.
Alternatively you can access the height and width information when you load the image out of the database and then set the height and width properties before assigning the image to the picture box.
You can get the height and width but you are going to have to load the whole image into memory using the system.drawing.image library, each time you need that info.
Better to save it as separate fields the first time you save it to the database, that is generally what I do.
Sounds like you want 2 more fields in your database, height and width.
I strongly believe that after a few hundred gigabytes of images you'll find yourself thinking that the file system and static file http servers are better suited than the databas for storing images. It also allows you to use thousands of existing free tools to work with, move, host, etc the images. Your database might get busy, and it's not easy to cluster.
Dim mobj_wc As New System.Net.WebClient
Dim obj_BookOriginalImage As System.Drawing.Bitmap
Dim ImageInBytes() As Byte = mobj_wc.DownloadData(mstr_BookURL & mds_BookDetails.Tables(0).Rows(0).Item("BookImage"))
'CREATE A MEMORY STREAM USING THE BYTES
Dim ImageStream As New IO.MemoryStream(ImageInBytes)
obj_BookOriginalImage = New System.Drawing.Bitmap(ImageStream)
mint_ImageWidth = obj_BookOriginalImage.Width