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How to export DataTable to Excel

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爱一瞬间的悲伤
爱一瞬间的悲伤 2020-11-22 15:36

How can I export a DataTable to Excel in C#? I am using Windows Forms. The DataTable is associated with a DataGridView control. I have

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  • 佛祖请我去吃肉
    佛祖请我去吃肉 (楼主)
    2020-11-22 15:43

    This solution is basically pushing List data to Excel, It uses DataTable to achieve this, I implemented an extension method, so basically there are two things needed. 1. An Extension Method.

    public static class ReportHelper
{
    public static string ToExcel(this IList data)
    {
        PropertyDescriptorCollection properties =
            TypeDescriptor.GetProperties(typeof(T));
        DataTable table = new DataTable();
        foreach (PropertyDescriptor prop in properties)
        {
            //table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
            if (prop.Attributes[typeof(FGMS.Entity.Extensions.ReportHeaderAttribute)] != null)
            {
                table.Columns.Add(GetColumnHeader(prop), Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
            }
        }

        //So it seems like when there is only one row of data the headers do not appear
        //so adding a dummy blank row which fixed the issues
        //Add a blank Row - Issue # 1471
        DataRow blankRow = table.NewRow();
        table.Rows.Add(blankRow);

        foreach (T item in data)
        {
            DataRow row = table.NewRow();
            foreach (PropertyDescriptor prop in properties)
                //row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
                if (prop.Attributes[typeof(FGMS.Entity.Extensions.ReportHeaderAttribute)] != null)
                {
                    row[GetColumnHeader(prop)] = prop.GetValue(item) ?? DBNull.Value;
                }
            table.Rows.Add(row);
        }
        table.TableName = "Results";
        var filePath = System.IO.Path.GetTempPath() + "\\" + System.Guid.NewGuid().ToString() + ".xls";
        table.WriteXml(filePath);

        return filePath;
    }

    private static string GetColumnHeader(PropertyDescriptor prop)
    {
        return ((FGMS.Entity.Extensions.ReportHeaderAttribute)(prop.Attributes[typeof(FGMS.Entity.Extensions.ReportHeaderAttribute)])).ReportHeaderText;
    }       
}
    1. Decorate your DTO classes with the Attribute [ReportHeaderAttribute("Column Name")]
    public class UserDTO
    {
        public int Id { get; set; }
        public int SourceId { get; set; }
        public string SourceName { get; set; }

        [ReportHeaderAttribute("User Type")]
        public string UsereType { get; set; }

        [ReportHeaderAttribute("Address")]
        public string Address{ get; set; }

        [ReportHeaderAttribute("Age")]
        public int Age{ get; set; }

        public bool IsActive { get; set; }

        [ReportHeaderAttribute("Active")]
        public string IsActiveString
        {
            get
            {
                return IsActive ? "Yes" : "No";
            }
        }}

    Everything that needs to be a column in the Excel has to be decorated with [ReportHeaderAttribute("Column Name")]

    Then Simply 

    Var userList = Service.GetUsers() //Returns List of UserDTO;
var excelFilePath = userList.ToExcel();

HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
            var stream = new FileStream(excelFilePath, FileMode.Open);
            result.Content = new StreamContent(stream);
            result.Content.Headers.ContentType =
                new MediaTypeHeaderValue("application/vnd.ms-excel");
            result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = "UserList.xls" };

            return result;

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