Working with the Uploaded Image
Once the user posts the data, we have to be able to parse the binary data and
send it to the database. Along with the main body of the code, we use a helper
function called SaveToDB() to achieve this.
private int SaveToDB(string imgName, byte[] imgbin, string
imgcontenttype)
{
//use the web.config to store the connection string
SqlConnection connection = new SqlConnection(ConfigurationSettings.AppSettings["DSN"]);
SqlCommand command = new SqlCommand( "INSERT INTO Image (img_name,img_data,img_contenttype)
VALUES ( @img_name, @img_data,@img_contenttype )", connection );
SqlParameter param0 = new SqlParameter( "@img_name", SqlDbType.VarChar,50
);
param0.Value = imgName;
command.Parameters.Add( param0 );
SqlParameter param1 = new SqlParameter( "@img_data", SqlDbType.Image
);
param1.Value = imgbin;
command.Parameters.Add( param1 );
SqlParameter param2 = new SqlParameter( "@img_contenttype", SqlDbType.VarChar,50
);
param2.Value = imgcontenttype;
command.Parameters.Add( param2 );
connection.Open();
int numRowsAffected = command.ExecuteNonQuery();
connection.Close();
return numRowsAffected;
}
In this function we are passing in 3 different parameters
imgName - the friendly name we want to give out image data
imgBin - the binary or Byte array of our data
imgContentType - the content type of our image. For example: image/gif
or image/jpeg
There are 3 parameters as SQLParameters and defines the type. Our first SQLParameter
is @img_name and is defined as a VarChar with a length of 50. The 2nd parameter,
@img_data, is the binary or Byte() of data and is defined with a data type
of Image. The last parameter is @img_contenttype, is defined as a VarChar with
a length of 50 characters. The remainder of the function opens a connection
to the database and executes the command by calling command.ExecuteNonQuery().
Calling our functions
Ok, now that we have our worker functions written, let's go ahead and get
our image data.
Stream imgStream = UploadFile.PostedFile.InputStream;
int imgLen = UploadFile.PostedFile.ContentLength;
string imgContentType = UploadFile.PostedFile.ContentType;
string imgName = txtImgName.Value;
byte[] imgBinaryData = new byte[imgLen];
We need to access three important pieces of data for our example. We need
the image:
Name (imgName_value)
Content-Type (imgContentType)
Image Data (imgBindaryData)
First we access to the image stream, which we are able to get by using
the property UploadFile.PostedFile.InputStream. (Remember, UploadFile was the
name of our upload control on the webform). We also need to know how
long the Byte
array we are going to create needs to be. We can get this number by
calling UploadFile.PostedFile.ContentLength, and storing it's value in
imgLen.
Once we have the length of the image, we create a byte array by byte[]
imgBinaryData
= new byte[imgLen]; We access the content type of the image by accessing
the ContentType property of UploadFile.PostedFile. Lastly we need
the friendly name we are going to use for the image.