uploading image to mysql table

[John Smith]

I know that uploading an image to a database has been covered, oh, about 3
trillion times. However, I haven't found anything covering uploading to a
MySQL database with .net. Please don't recommend storing the image to the
filesystem and only keeping a pointer to that in the table. I want to dump
the image to a table. My code dumps the data into the table, however, I get
the following error when trying to view the image "the image ... cannot be
displayed because it contains errors".

The image data is stored in a large-blob field, extension is stored in
varchar, and a description is stored in a varchar. I think the problem
has to do with special characters in the image data. MySQL seems to be real
picky about that stuff. Looking at
http://dev.mysql.com/doc/mysql/en/String_syntax.html, there's a blurb " If
you want to insert binary data into a string column (such as a BLOB), the
following characters must be represented by escape sequences: " towards the
bottom.

So, I guess I need to somehow parse the inputstream and/or byte array and
replace those characters as needed. This is where I'm stuck. I could write
a function to replace the data with the proper escape sequence but each byte
in the arrFile array contains an integer value as shown with the loop:

***********
for (int i=0; i<=intFileLen-1; i++)
Response.Write(arrFile);
***********

Is there anyway to view the raw data or is that the raw data? Any ideas?
Thanks in advance. The code follows


// Determine File Type
int fileLen = txtFileContents.PostedFile.FileName.Length;
strFileExtension =
txtFileContents.PostedFile.FileName.Substring(fileLen-4,4);

// Grab the contents of uploaded file
intFileLen = txtFileContents.PostedFile.ContentLength;

byte[] arrFile = new byte[intFileLen];
objStream = txtFileContents.PostedFile.InputStream;
objStream.Read( arrFile, 0, intFileLen );
objStream.Close();

// Add Uploaded file to database
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrFile+"\" )";

cmdInsert = new OdbcCommand( strInsert, conMyData );

conMyData.Open();
cmdInsert.ExecuteNonQuery();

conMyData.Close();
}

 

[Sunny]

Hi,
I haven't done that, but as I see, you are using the ODBC driver for
MySQL. Have you tried their ADO.Net provider as well. As I looked thru
code, it supports binary blobs, so maybe this is the way to go.

Sunny

 

[John Smith]

Sunny--

Thanks for your reply. Are you talking about the ByteFX provider? No I
hadn't tried that but I just did. Same thing.

I did manage to figure out how to replace special characters in the data
with escape sequences...I think. Though, it still doesn't work. What I did
was convert the image data byte array into an ascii encoded string, used the
Replace method to replace the special chars with escape sequences and then
converted that back to a byte array. Like I said, though, it still didn't
work. Code is below:

// txtFileContents is the text upload control
//grab contents and put into byte array
intFileLen = txtFileContents.PostedFile.ContentLength;
byte[] arrFile = new byte[intFileLen];
objStream = txtFileContents.PostedFile.InputStream;
objStream.Read( arrFile, 0, intFileLen );
objStream.Close();

// now convert that to string and process escape sequences as needed
Encoding encEncoder = ASCIIEncoding.ASCII;
string str = encEncoder.GetString(arrFile,0,arrFile.GetLength(0));
string str2 =
str.Replace("\"","\\\"").Replace("'","\\'").Replace("\\","\\\\").Replace(((c
har)0).ToString(),"\\0");

// now convert back to byte array
byte[] arrCrap = unicode.GetBytes(str2);

// insert into table...left out the ado connection stuff
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrCrap+"\" )";

// end
//////////////////////////////

Hi,
I haven't done that, but as I see, you are using the ODBC driver for
MySQL. Have you tried their ADO.Net provider as well. As I looked thru
code, it supports binary blobs, so maybe this is the way to go.

Sunny

I know that uploading an image to a database has been covered, oh, about 3
trillion times. However, I haven't found anything covering uploading to a
MySQL database with .net. Please don't recommend storing the image to the
filesystem and only keeping a pointer to that in the table. I want to dump
the image to a table. My code dumps the data into the table, however, I get
the following error when trying to view the image "the image ... cannot be
displayed because it contains errors".

The image data is stored in a large-blob field, extension is stored in
varchar, and a description is stored in a varchar. I think the problem
has to do with special characters in the image data. MySQL seems to be real
picky about that stuff. Looking at
http://dev.mysql.com/doc/mysql/en/String_syntax.html, there's a blurb " If
you want to insert binary data into a string column (such as a BLOB), the
following characters must be represented by escape sequences: " towards the
bottom.

So, I guess I need to somehow parse the inputstream and/or byte array and
replace those characters as needed. This is where I'm stuck. I could write
a function to replace the data with the proper escape sequence but each byte
in the arrFile array contains an integer value as shown with the loop:

***********
for (int i=0; i<=intFileLen-1; i++)
Response.Write(arrFile);
***********

Is there anyway to view the raw data or is that the raw data? Any ideas?
Thanks in advance. The code follows


// Determine File Type
int fileLen = txtFileContents.PostedFile.FileName.Length;
strFileExtension =
txtFileContents.PostedFile.FileName.Substring(fileLen-4,4);

// Grab the contents of uploaded file
intFileLen = txtFileContents.PostedFile.ContentLength;

byte[] arrFile = new byte[intFileLen];
objStream = txtFileContents.PostedFile.InputStream;
objStream.Read( arrFile, 0, intFileLen );
objStream.Close();

// Add Uploaded file to database
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrFile+"\" )";

cmdInsert = new OdbcCommand( strInsert, conMyData );

conMyData.Open();
cmdInsert.ExecuteNonQuery();

conMyData.Close();
}

 

[Sunny]

Hi John,

Sunny--

Thanks for your reply. Are you talking about the ByteFX provider? No I
hadn't tried that but I just did. Same thing.

Yes, that was my idea.

// now convert back to byte array
byte[] arrCrap = unicode.GetBytes(str2);

// insert into table...left out the ado connection stuff
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrCrap+"\" )";

And how this works??? How can you add byte[] a part of string
concatenation? Does the last line compile at all?

Sunny

 

[John Smith]

Sunny--

Yup. The program compiles and runs fine. I don't know how or why it works
but this is the same code I got from my ASP.Net Unleashed book. Of course,
they are using a MSSQL server for the dbms and it has an "image" data type
built in. MySQL has only the BLOB type.

Hi John,

Sunny--

Thanks for your reply. Are you talking about the ByteFX provider? No I
hadn't tried that but I just did. Same thing.

Yes, that was my idea.

// now convert back to byte array
byte[] arrCrap = unicode.GetBytes(str2);

// insert into table...left out the ado connection stuff
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrCrap+"\" )";

And how this works??? How can you add byte[] a part of string
concatenation? Does the last line compile at all?

Sunny

 

[Sunny]

Hi John,

this code is broken. After executing this line the content of the
strInsert is:

Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values ("myfie.txt",
"myImageType", "System.Byte[]" )

As you can see, putting a byte[] in the string concatenation actually
invokes the .ToString method of the Array class, which in this case
outputs only "System.Byte[]", but not the actual content of the array.

So, try to replace this:
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrCrap+"\" )";

with this:
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+str2+"\" )";

Now your modified string will be included in the insert statement.

I can not test it now, but at least removes an obvious problem.


Sunny

Sunny--

Yup. The program compiles and runs fine. I don't know how or why it works
but this is the same code I got from my ASP.Net Unleashed book. Of course,
they are using a MSSQL server for the dbms and it has an "image" data type
built in. MySQL has only the BLOB type.

Hi John,

Sunny--

Thanks for your reply. Are you talking about the ByteFX provider? No I
hadn't tried that but I just did. Same thing.

Yes, that was my idea.

// now convert back to byte array
byte[] arrCrap = unicode.GetBytes(str2);

// insert into table...left out the ado connection stuff
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrCrap+"\" )";

And how this works??? How can you add byte[] a part of string
concatenation? Does the last line compile at all?

Sunny

 

[John Smith]

Sunny--

I had wondered about that. The data that's actually in the table does indeed
show as "System.Byte[]". But when I double-clicked that in the MySQL
control center, it loaded the image viewer app. That led me to think there
was something else there. The book I'm using has this:

/////////////////////////////////////
// Add Uploaded file to database
conMyData = new SqlConnection( @"Server=localhost;Integrated
Security=SSPI;Database=myData" );
strInsert = "Insert Uploads ( u_title, u_documentType, u_document ) " +
"Values (@title, @fileType, @document )";
cmdInsert = new SqlCommand( strInsert, conMyData );
cmdInsert.Parameters.Add( "@title", txtFileTitle.Text );
cmdInsert.Parameters.Add( "@fileType", strFileType );
cmdInsert.Parameters.Add( "@document", arrFile );
conMyData.Open();
cmdInsert.ExecuteNonQuery();
conMyData.Close();
/////////////////////////////////////

But using the Parameters.Add failed when I tried so I ended up with what you
see. Is the code above not doing the exact same thing? Regardless I did
try the using the str2 variable. It didn't work either. I'm assuming
because it's a string and not binary data? Can you tell I don't know what
I'm doing?

Thanks for your willingness to help me on this.

Hi John,

this code is broken. After executing this line the content of the
strInsert is:

Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values ("myfie.txt",
"myImageType", "System.Byte[]" )

As you can see, putting a byte[] in the string concatenation actually
invokes the .ToString method of the Array class, which in this case
outputs only "System.Byte[]", but not the actual content of the array.

So, try to replace this:
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrCrap+"\" )";

with this:
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+str2+"\" )";

Now your modified string will be included in the insert statement.

I can not test it now, but at least removes an obvious problem.


Sunny

Sunny--

Yup. The program compiles and runs fine. I don't know how or why it works
but this is the same code I got from my ASP.Net Unleashed book. Of course,
they are using a MSSQL server for the dbms and it has an "image" data type
built in. MySQL has only the BLOB type.

Hi John,



Sunny--

Thanks for your reply. Are you talking about the ByteFX provider? No I
hadn't tried that but I just did. Same thing.

Yes, that was my idea.

// now convert back to byte array
byte[] arrCrap = unicode.GetBytes(str2);

// insert into table...left out the ado connection stuff
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrCrap+"\" )";



And how this works??? How can you add byte[] a part of string
concatenation? Does the last line compile at all?

Sunny

 

[Sunny]

Now I see the first mistake
Parameters.Add does a lot more work than just replacing strings in the
command text. Now, lets try to solve the problem. I have no time now to
install MySql and test, so, please, check this:

1. After you read the file into the array, can you create an image from
this array? Without any manipulations?

2. If step one is OK: using ByteFX lib, recreate the last part of code
you have posted:

conMyData = new MySqlConnection ....

cmdInsert = new MySqlCommand.....

all the Add commands, etc.

If something fails, please report the exact exception you receive.

3. If step 2 is OK, and you can see some data in the DB, but still can
not view it, please read it back using ByteFX library and compare the
received data to originally stored data. You may try to create an image,
or you can write it to a file and compare both files to see what is the
difference.

Sunny

Sunny--

I had wondered about that. The data that's actually in the table does indeed
show as "System.Byte[]". But when I double-clicked that in the MySQL
control center, it loaded the image viewer app. That led me to think there
was something else there. The book I'm using has this:

/////////////////////////////////////
// Add Uploaded file to database
conMyData = new SqlConnection( @"Server=localhost;Integrated
Security=SSPI;Database=myData" );
strInsert = "Insert Uploads ( u_title, u_documentType, u_document ) " +
"Values (@title, @fileType, @document )";
cmdInsert = new SqlCommand( strInsert, conMyData );
cmdInsert.Parameters.Add( "@title", txtFileTitle.Text );
cmdInsert.Parameters.Add( "@fileType", strFileType );
cmdInsert.Parameters.Add( "@document", arrFile );
conMyData.Open();
cmdInsert.ExecuteNonQuery();
conMyData.Close();
/////////////////////////////////////

But using the Parameters.Add failed when I tried so I ended up with what you
see. Is the code above not doing the exact same thing? Regardless I did
try the using the str2 variable. It didn't work either. I'm assuming
because it's a string and not binary data? Can you tell I don't know what
I'm doing?

Thanks for your willingness to help me on this.

Hi John,

this code is broken. After executing this line the content of the
strInsert is:

Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values ("myfie.txt",
"myImageType", "System.Byte[]" )

As you can see, putting a byte[] in the string concatenation actually
invokes the .ToString method of the Array class, which in this case
outputs only "System.Byte[]", but not the actual content of the array.

So, try to replace this:
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrCrap+"\" )";

with this:
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+str2+"\" )";

Now your modified string will be included in the insert statement.

I can not test it now, but at least removes an obvious problem.


Sunny

Sunny--

Yup. The program compiles and runs fine. I don't know how or why it works
but this is the same code I got from my ASP.Net Unleashed book. Of course,
they are using a MSSQL server for the dbms and it has an "image" data type
built in. MySQL has only the BLOB type.



Hi John,



Sunny--

Thanks for your reply. Are you talking about the ByteFX provider? No I
hadn't tried that but I just did. Same thing.

Yes, that was my idea.

// now convert back to byte array
byte[] arrCrap = unicode.GetBytes(str2);

// insert into table...left out the ado connection stuff
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrCrap+"\" )";



And how this works??? How can you add byte[] a part of string
concatenation? Does the last line compile at all?

Sunny

 

[John Smith]

Success!!!! Many, many thanks Sunny. That was the problem.

Final code for anyone interested is:
// upload.aspx
//////////////////////////////////////////////////////////////
void Button_Click(Object sender , EventArgs e)
{
string strFileExtension;
string strFileType;
int intFileLen;
Stream objStream;
string strInsert;

if ( txtFileContents.PostedFile != null )
{
// Determine File Type
int fileLen = txtFileContents.PostedFile.FileName.Length;
strFileExtension =
txtFileContents.PostedFile.FileName.Substring(fileLen-4,4);
switch (strFileExtension.ToLower()) {
case ".bmp":
strFileType = "bmp";
break;
case ".jpg":
strFileType = "jpg";
break;
case ".gif":
strFileType = "gif";
break;
}

// Grab the contents of uploaded file
intFileLen = txtFileContents.PostedFile.ContentLength;
byte[] arrFile = new byte[intFileLen];
objStream = txtFileContents.PostedFile.InputStream;
objStream.Read( arrFile, 0, intFileLen );
objStream.Close();

// Add Uploaded file to database
string myConnectionString = "Database=a_mysql_db;Data
Source=localhost;User Id=userid;Password=passwd";

MySqlConnection myConnection = new MySqlConnection(myConnectionString);

string myInsertQuery = "Insert Into pics (TITLE,IMAGE_TYPE,IMAGE ) Values
(@title,@imagetype,@image)";
MySqlCommand myCommand = new MySqlCommand(myInsertQuery);
myCommand.Parameters.Add("@title","blah");
myCommand.Parameters.Add("@imagetype","jpg");
myCommand.Parameters.Add("@image",arrFile);

myCommand.Connection = myConnection;
myConnection.Open();
myCommand.ExecuteNonQuery();
myCommand.Connection.Close();

}

}
//////////////////////////////////////////////////////////////
// viewimage.aspx
void Page_Load(Object sender , EventArgs e)
{
int intItemID;
OdbcConnection conMyData;
string strSelect;
OdbcCommand cmdSelect;
OdbcDataReader dtrSearch;

intItemID = Convert.ToInt32(Request.Params["id"]);

conMyData = new OdbcConnection("DSN=a_dsn"); // this hasn't been switched
to the ado.net provider

strSelect = "SELECT IMAGE_TYPE, IMAGE, TITLE From pics "
+ "WHERE PIC_ID=35"; // hard coded record...will really pull from
querystring

cmdSelect = new OdbcCommand( strSelect, conMyData );
conMyData.Open();

dtrSearch = cmdSelect.ExecuteReader();

if ( dtrSearch.Read())
{
// set Content Type
Response.ClearHeaders();
Response.AppendHeader("Content-Transfer-Encoding","binary");

Response.ContentType = "image/jpeg";
Response.BinaryWrite( (byte[])dtrSearch["IMAGE"] );
}

dtrSearch.Close();
conMyData.Close();
Response.End();
}

// now you can call viewimage.aspx within an <img> tag like so:
<img src="viewimage.aspx?image_id=x" />

///////////////////////////////////////////////////////////////

Now I see the first mistake
Parameters.Add does a lot more work than just replacing strings in the
command text. Now, lets try to solve the problem. I have no time now to
install MySql and test, so, please, check this:

1. After you read the file into the array, can you create an image from
this array? Without any manipulations?

2. If step one is OK: using ByteFX lib, recreate the last part of code
you have posted:

conMyData = new MySqlConnection ....

cmdInsert = new MySqlCommand.....

all the Add commands, etc.

If something fails, please report the exact exception you receive.

3. If step 2 is OK, and you can see some data in the DB, but still can
not view it, please read it back using ByteFX library and compare the
received data to originally stored data. You may try to create an image,
or you can write it to a file and compare both files to see what is the
difference.

Sunny

Sunny--

I had wondered about that. The data that's actually in the table does indeed
show as "System.Byte[]". But when I double-clicked that in the MySQL
control center, it loaded the image viewer app. That led me to think there
was something else there. The book I'm using has this:

/////////////////////////////////////
// Add Uploaded file to database
conMyData = new SqlConnection( @"Server=localhost;Integrated
Security=SSPI;Database=myData" );
strInsert = "Insert Uploads ( u_title, u_documentType, u_document ) " +
"Values (@title, @fileType, @document )";
cmdInsert = new SqlCommand( strInsert, conMyData );
cmdInsert.Parameters.Add( "@title", txtFileTitle.Text );
cmdInsert.Parameters.Add( "@fileType", strFileType );
cmdInsert.Parameters.Add( "@document", arrFile );
conMyData.Open();
cmdInsert.ExecuteNonQuery();
conMyData.Close();
/////////////////////////////////////

But using the Parameters.Add failed when I tried so I ended up with what you
see. Is the code above not doing the exact same thing? Regardless I did
try the using the str2 variable. It didn't work either. I'm assuming
because it's a string and not binary data? Can you tell I don't know what
I'm doing?

Thanks for your willingness to help me on this.

Hi John,

this code is broken. After executing this line the content of the
strInsert is:

Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values ("myfie.txt",
"myImageType", "System.Byte[]" )

As you can see, putting a byte[] in the string concatenation actually
invokes the .ToString method of the Array class, which in this case
outputs only "System.Byte[]", but not the actual content of the array.

So, try to replace this:
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrCrap+"\" )";

with this:
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE ) Values (\""+
txtFileTitle.Text+"\", \""+strFileType+"\", \""+str2+"\" )";

Now your modified string will be included in the insert statement.

I can not test it now, but at least removes an obvious problem.


Sunny


Sunny--

Yup. The program compiles and runs fine. I don't know how or why it works
but this is the same code I got from my ASP.Net Unleashed book. Of course,
they are using a MSSQL server for the dbms and it has an "image"

data
type

built in. MySQL has only the BLOB type.



Hi John,



Sunny--

Thanks for your reply. Are you talking about the ByteFX

provider?
No I

hadn't tried that but I just did. Same thing.

Yes, that was my idea.

// now convert back to byte array
byte[] arrCrap = unicode.GetBytes(str2);

// insert into table...left out the ado connection stuff
strInsert = "Insert Into pics ( TITLE, IMAGE_TYPE, IMAGE )

Values
(\""+

txtFileTitle.Text+"\", \""+strFileType+"\", \""+arrCrap+"\" )";



And how this works??? How can you add byte[] a part of string
concatenation? Does the last line compile at all?

Sunny

 

[Sunny]

Hi John,

this is good that it works.

Now, final words:

Always put your data access code in try/finaly block. Always.

Your last lines in the oNClick method shoud be:

try
{
myConnection.Open();
myCommand.ExecuteNonQuery();
}
catch //this is optional, if you want to
//report the error
{
// report the error
}
finally
{
myConnection.Close();
}

This way you quarantee that even if something goes wrong, the connection
will always be closed.


Good luck
Sunny

 

[John Smith]

Cool.

Thanks again for your help!