ASP.Net: Convert Text returned from API to CSV file using C# and VB.Net

Hi Waghmare,

Refer below code.

Here i am reading the content from Text file.

HTML

<asp:Button ID="btnExportCsv" runat="server" Text="Export To CSV" OnClick="ExportCSV" />

Namespaces

C#

using System.Data;
using System.IO;
using System.Text;

VB.Net

Imports System.Data
Imports System.IO
Imports System.Text

Code

protected void ExportCSV(object sender, EventArgs e)
{
    string csvPath = Server.MapPath("~/Files/Customers.txt");
    string[] csvData = File.ReadAllLines(csvPath);
    DataTable dt = new DataTable();
    for (int i = 0; i < csvData.Length; i++)
    {
        string[] data = csvData[i].Split(',');
        if (i == 0)
        {
            dt.Columns.Add(data[0]);
            dt.Columns.Add(data[1]);
            dt.Columns.Add(data[2]);
            dt.Columns.Add(data[3]);
            dt.Columns.Add(data[4]);
        }
        else
        {
            dt.Rows.Add(data[0], data[1], data[2], data[3], data[4] + "," + data[4]);
        }
    }

    StringBuilder sb = new StringBuilder();

    for (int k = 0; k < dt.Columns.Count; k++)
    {
        sb.Append(dt.Columns[k].ColumnName + ',');
    }
    sb.Append("\r\n");
    for (int i = 0; i < dt.Rows.Count; i++)
    {
        for (int k = 0; k < dt.Columns.Count; k++)
        {
            sb.Append(dt.Rows[i][k].ToString().Replace(",", ";") + ',');
        }
        sb.Append("\r\n");
    }

    Response.Clear();
    Response.Buffer = true;
    Response.AddHeader("content-disposition", "attachment;filename=Data.csv");
    Response.Charset = "";
    Response.ContentType = "application/text";
    Response.Output.Write(sb.ToString());
    Response.Flush();
    Response.End();
}

VB.Net

Protected Sub ExportCSV(ByVal sender As Object, ByVal e As EventArgs)
    Dim csvPath As String = Server.MapPath("~/Files/Customers.txt")
    Dim csvData As String() = File.ReadAllLines(csvPath)
    Dim dt As DataTable = New DataTable()
    For i As Integer = 0 To csvData.Length - 1
        Dim data As String() = csvData(i).Split(","c)
        If i = 0 Then
            dt.Columns.Add(data(0))
            dt.Columns.Add(data(1))
            dt.Columns.Add(data(2))
            dt.Columns.Add(data(3))
            dt.Columns.Add(data(4))
        Else
            dt.Rows.Add(data(0), data(1), data(2), data(3), data(4) & "," & data(4))
        End If
    Next

    Dim sb As StringBuilder = New StringBuilder()
    For k As Integer = 0 To dt.Columns.Count - 1
        sb.Append(dt.Columns(k).ColumnName + ","c)
    Next

    sb.Append(vbCrLf)
    For i As Integer = 0 To dt.Rows.Count - 1
        For k As Integer = 0 To dt.Columns.Count - 1
            sb.Append(dt.Rows(i)(k).ToString().Replace(",", ";") + ","c)
        Next

        sb.Append(vbCrLf)
    Next

    Response.Clear()
    Response.Buffer = True
    Response.AddHeader("content-disposition", "attachment;filename=Data.csv")
    Response.Charset = ""
    Response.ContentType = "application/text"
    Response.Output.Write(sb.ToString())
    Response.Flush()
    Response.End()
End Sub

Screenshot