Question

hi i have web application in which i need to store image into one of column of datatble
but i am getting error when doing this.Here is my code i tried for this.

DataTable dt = new DataTable();

dt.Columns.Add("Companyaddress", typeof(System.String));
dt.Columns.Add("CompEmail", typeof(System.String));
dt.Columns.Add("CompTelephone", typeof(System.String));
dt.Columns.Add("logoname", typeof(byte[]));
//dt.Columns.Add("logoname", typeof(System.Byte[]));

for (int rowNumber = 0; rowNumber < imageDataSet.Tables[0].Rows.Count; rowNumber++)
{
    imageDataSet.Tables[0].Rows[rowNumber]["logoname"] = GetByteArray("abc.jpg");
    dt.Rows.Add(imageDataSet.Tables[0].Rows[rowNumber][0].ToString(), 
                imageDataSet.Tables[0].Rows[rowNumber][1].ToString(), 
                imageDataSet.Tables[0].Rows[rowNumber][2].ToString(), 
                imageDataSet.Tables[0].Rows[rowNumber][3].ToString());
 }

Getting error

Type of value has a mismatch with column typeCouldn’t store
in logoname Column. Expected type is Byte[].

on this line

dt.Rows.Add(imageDataSet.Tables[0].Rows[rowNumber][0].ToString(), imageDataSet.Tables[0].Rows[rowNumber][1].ToString(), imageDataSet.Tables[0].Rows[rowNumber][2].ToString(), imageDataSet.Tables[0].Rows[rowNumber][3].ToString());

This is functon i call to get image

private byte[] GetByteArray(String strFileName)
{
    System.IO.FileStream fs = new System.IO.FileStream(strFileName, System.IO.FileMode.Open);
    // initialise the binary reader from file streamobject
    System.IO.BinaryReader br = new System.IO.BinaryReader(fs);
    // define the byte array of filelength

    byte[] imgbyte = new byte[fs.Length + 1];
    // read the bytes from the binary reader

    imgbyte = br.ReadBytes(Convert.ToInt32((fs.Length)));
    // add the image in bytearray

    br.Close();
    // close the binary reader

    fs.Close();
    // close the file stream
    return imgbyte;
}

what to do? need help.

Answer 1

Problem is the way you are adding the row the DataTable.

You should use:

dt.Rows.Add(imageDataSet.Tables[0].Rows[rowNumber][0].ToString(),
    imageDataSet.Tables[0].Rows[rowNumber][1].ToString(), 
    imageDataSet.Tables[0].Rows[rowNumber][2].ToString(), 
    imageDataSet.Tables[0].Rows[rowNumber][3] as byte[]);

Since your Column 3 corresponds to the byte array field, you may cast it to byte[] type. Earlier you were using .ToString whereas the method was expecting a byte[] type argument. Hence the exception.

For clarity, you may re-write your loop using DataTable.NewRow as:

for (int rowNumber = 0; rowNumber < imageDataSet.Tables[0].Rows.Count; rowNumber++)
{
    imageDataSet.Tables[0].Rows[rowNumber]["logoname"] = GetByteArray("abc.jpg");
    DataRow dr = dt.NewRow();
    dr["Companyaddress"] = imageDataSet.Tables[0].Rows[rowNumber][0].ToString();
    dr["CompEmail"] = imageDataSet.Tables[0].Rows[rowNumber][1].ToString();
    dr["CompTelephone"] = imageDataSet.Tables[0].Rows[rowNumber][2].ToString();
    dr["logoname"] = imageDataSet.Tables[0].Rows[rowNumber][3] as byte[];
    dt.Rows.Add(dr);
}