在图片框C＃中查看三层架构中的联系人照片

Question

I want to write a phonebook in C # with a three-layer architecture, but I do not have enough of this architecture. We have a datagridview that displays the image of each person in the picturebox when we click on each of the rows. But it does not work. I do not know where the problem is. Please guide me. I recently got acquainted with this architecture.

DAL code:

 public void GetBinaryImage(int Id)
    {

        context.People.Select(a => new { a.Id, a.PersonImage }).Where(a => a.Id == Id) ;

    }

BLL code

 public void GrtBinaryImage(int person_Id)
    {

        Myperson.GetBinaryImage(person_Id);

    }

PL code

 private void dataGridView_CellContentClick(object sender, DataGridViewCellEventArgs e)
    {
        if (dataGridView.SelectedRows.Count > 0)
        {
            int Id = Convert.ToInt32(dataGridView.SelectedRows[0].Cells["Id"].Value);
            showpictureBox.Image = bytearytoimage(person.GrtBinaryImage(Id));


        }
    }

    private Image bytearytoimage(object v)
    {
        MemoryStream stream = new MemoryStream(v);
        return Image.FromStream(stream);
    }

I get the error:

"Argument 1: cannot convert from 'void' to object".

I know I wrote a mistake, please guide me.

Answer 1

You seem to a have a lack of understanding with returning values from functions.

First of all your DLL function doesn't return anything, I can only assume you are trying to return PersonImage which is hopefully a byte[] . In addition, you need to change the code to select only the value you want to return:

DLL

public byte[] GetBinaryImage(int Id)
{
    byte[] result = context.People.Where(a => a.Id == Id).Select(a => a.PersonImage).SingleOrDefault();
    return result;
}

Next up, you have the same problem with return values in your BLL:

BLL

public byte[] GrtBinaryImage(int person_Id)
{
    return Myperson.GetBinaryImage(person_Id);
}

That should be enough to get what you want, although I would also recommend changing the parameter type in your bytearytoimage function specifically to byte[] :

PL

private Image bytearytoimage(byte[] v)
{
    MemoryStream stream = new MemoryStream(v);
    return Image.FromStream(stream);
}

Note that this all hinges on the fact that PersonImage is a byte[] . If it isn't then you should update your question to be more specific about what data you have to work with.