如何使用 asp.net 核心从数据库的特定行下载图像

Question

我想从数据库中获取图像并在我的 react-native 中显示它app.where我做错了吗？

public IActionResult DownloadFile(int id)
{
    DataTable table = new DataTable();
    string query = @"select image from mydb.courses where id=@id";
    string sqlDataSource = _configuration.GetConnectionString("UsersAppCon");
    MySqlDataReader myReader;
    using (MySqlConnection mycon = new MySqlConnection(sqlDataSource))
    {
        mycon.Open();
        using (MySqlCommand myCommand = new MySqlCommand(query, mycon))
        {
            myReader = myCommand.ExecuteReader();
            table.Load(myReader);
            var fs = new FileStream(myReader, FileMode.Open);
            return File(fs, "application/octet-stream");
            myReader.Close();
            mycon.Close();
        }
    }
}

Answer 1

我修好了。

[HttpGet("{id}")]
public IActionResult DownloadFile(int id)
{
    string pathImage = "";
    DataTable table = new DataTable();
    string query = @"select image from mydb.courses where id=@id";
    string sqlDataSource = _configuration.GetConnectionString("UsersAppCon");
    MySqlDataReader myReader;
    using (MySqlConnection mycon = new MySqlConnection(sqlDataSource))
    {
        mycon.Open();
        using (MySqlCommand myCommand = new MySqlCommand(query, mycon))
        {
            myCommand.Parameters.AddWithValue("@id", id);
            pathImage = (string)myCommand.ExecuteScalar();
            mycon.Close();
        }
    }
    var path = @$"{pathImage}";
    var fs = new FileStream(path, FileMode.Open);
    return File(fs, "image/jpeg");
}