Import Excel File to DataSet

private static ColumnType getDefaultType() {
    return new ColumnType(typeof(String));
}

struct ColumnType {
    public Type type;
    private string name;
    public ColumnType(Type type) { this.type = type; this.name = type.ToString().ToLower(); }
    public object ParseString(string input) {
        if (String.IsNullOrEmpty(input))
            return DBNull.Value;
        switch (type.ToString()) {
            case "system.datetime":
                return DateTime.Parse(input);
            case "system.decimal":
                return decimal.Parse(input);
            case "system.boolean":
                return bool.Parse(input);
            default:
                return input;
        }
    }
}

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Data;
using System.Data.OleDb;
using System.Xml;
using System.Web;

namespace ConvertToExcel {
    public class ExcelImport {
        public static DataSet ImportExcelXLS(HttpPostedFile file, bool hasHeaders) {
            string fileName = Path.GetTempFileName();
            file.SaveAs(fileName);

            return ImportExcelXLS(fileName, hasHeaders);
        }
        private static DataSet ImportExcelXLS(string FileName, bool hasHeaders) {
            string HDR = hasHeaders ? "Yes" : "No";
            string strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + FileName + ";Extended Properties=\"Excel 8.0;HDR=" + HDR + ";IMEX=1\"";

            DataSet output = new DataSet();

            using (OleDbConnection conn = new OleDbConnection(strConn)) {
                conn.Open();

                DataTable dt = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });

                foreach (DataRow row in dt.Rows) {
                    string sheet = row["TABLE_NAME"].ToString();

                    OleDbCommand cmd = new OleDbCommand("SELECT * FROM [" + sheet + "]", conn);
                    cmd.CommandType = CommandType.Text;

                    DataTable outputTable = new DataTable(sheet);
                    output.Tables.Add(outputTable);
                    new OleDbDataAdapter(cmd).Fill(outputTable);
                }
            }
            return output;
        }

        struct ColumnType {
            public Type type;
            private string name;
            public ColumnType(Type type) { this.type = type; this.name = type.ToString().ToLower(); }
            public object ParseString(string input) {
                if (String.IsNullOrEmpty(input))
                    return DBNull.Value;
                switch (type.ToString()) {
                    case "system.datetime":
                        return DateTime.Parse(input);
                    case "system.decimal":
                        return decimal.Parse(input);
                    case "system.boolean":
                        return bool.Parse(input);
                    default:
                        return input;
                }
            }
        }
        public static DataSet ImportExcelXML(HttpPostedFile file, bool hasHeaders, bool autoDetectColumnType) {
            return ImportExcelXML(file.InputStream, hasHeaders, autoDetectColumnType);
        }
        public static DataSet ImportExcelXML(Stream inputFileStream, bool hasHeaders, bool autoDetectColumnType) {
            XmlDocument doc = new XmlDocument();
            doc.Load(new XmlTextReader(inputFileStream));
            XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);

            nsmgr.AddNamespace("o", "urn:schemas-microsoft-com:office:office");
            nsmgr.AddNamespace("x", "urn:schemas-microsoft-com:office:excel");
            nsmgr.AddNamespace("ss", "urn:schemas-microsoft-com:office:spreadsheet");

            DataSet ds = new DataSet();

            foreach (XmlNode node in doc.DocumentElement.SelectNodes("//ss:Worksheet", nsmgr)) {
                DataTable dt = new DataTable(node.Attributes["ss:Name"].Value);
                ds.Tables.Add(dt);
                XmlNodeList rows = node.SelectNodes("ss:Table/ss:Row", nsmgr);
                if (rows.Count > 0) {
                    List<ColumnType> columns = new List<ColumnType>();
                    int startIndex = 0;
                    if (hasHeaders) {
                        foreach (XmlNode data in rows[0].SelectNodes("ss:Cell/ss:Data", nsmgr)) {
                            columns.Add(new ColumnType(typeof(string)));//default to text
                            dt.Columns.Add(data.InnerText, typeof(string));
                        }
                        startIndex++;
                    }
                    if (autoDetectColumnType && rows.Count > 0) {
                        XmlNodeList cells = rows[startIndex].SelectNodes("ss:Cell", nsmgr);
                        int actualCellIndex = 0;
                        for (int cellIndex = 0; cellIndex < cells.Count; cellIndex++) {
                            XmlNode cell = cells[cellIndex];
                            if (cell.Attributes["ss:Index"] != null)
                                actualCellIndex = int.Parse(cell.Attributes["ss:Index"].Value) - 1;

                            ColumnType autoDetectType = getType(cell.SelectSingleNode("ss:Data", nsmgr));

                            if (actualCellIndex >= dt.Columns.Count) {
                                dt.Columns.Add("Column" + actualCellIndex.ToString(), autoDetectType.type);
                                columns.Add(autoDetectType);
                            } else {
                                dt.Columns[actualCellIndex].DataType = autoDetectType.type;
                                columns[actualCellIndex] = autoDetectType;
                            }

                            actualCellIndex++;
                        }
                    }
                    for (int i = startIndex; i < rows.Count; i++) {
                        DataRow row = dt.NewRow();
                        XmlNodeList cells = rows[i].SelectNodes("ss:Cell", nsmgr);
                        int actualCellIndex = 0;
                        for (int cellIndex = 0; cellIndex < cells.Count; cellIndex++) {
                            XmlNode cell = cells[cellIndex];
                            if (cell.Attributes["ss:Index"] != null)
                                actualCellIndex = int.Parse(cell.Attributes["ss:Index"].Value) - 1;

                            XmlNode data = cell.SelectSingleNode("ss:Data", nsmgr);

                            if (actualCellIndex >= dt.Columns.Count) {
                                for (int i = dt.Columns.Count; i < actualCellIndex; i++) {
                                    dt.Columns.Add("Column" + actualCellIndex.ToString(), typeof(string));
                                    columns.Add(getDefaultType());
                                }
                                ColumnType autoDetectType = getType(cell.SelectSingleNode("ss:Data", nsmgr));
                                dt.Columns.Add("Column" + actualCellIndex.ToString(), typeof(string));
                                columns.Add(autoDetectType);
                            }
                            if (data != null)
                                row[actualCellIndex] = data.InnerText;

                            actualCellIndex++;
                        }

                        dt.Rows.Add(row);
                    }
                }
            }
            return ds;

            //<?xml version="1.0"?>
            //<?mso-application progid="Excel.Sheet"?>
            //<Workbook>
            // <Worksheet ss:Name="Sheet1">
            //  <Table>
            //   <Row>
            //    <Cell><Data ss:Type="String">Item Number</Data></Cell>
            //    <Cell><Data ss:Type="String">Description</Data></Cell>
            //    <Cell ss:StyleID="s21"><Data ss:Type="String">Item Barcode</Data></Cell>
            //   </Row>
            // </Worksheet>
            //</Workbook>
        }

        private static ColumnType getDefaultType() {
            return new ColumnType(typeof(String));
        }

        private static ColumnType getType(XmlNode data) {
            string type = null;
            if (data.Attributes["ss:Type"] == null || data.Attributes["ss:Type"].Value == null)
                type = "";
            else
                type = data.Attributes["ss:Type"].Value;

            switch (type) {
                case "DateTime":
                    return new ColumnType(typeof(DateTime));
                case "Boolean":
                    return new ColumnType(typeof(Boolean));
                case "Number":
                    return new ColumnType(typeof(Decimal));
                case "":
                    decimal test2;
                    if (data == null || String.IsNullOrEmpty(data.InnerText) || decimal.TryParse(data.InnerText, out test2)) {
                        return new ColumnType(typeof(Decimal));
                    } else {
                        return new ColumnType(typeof(String));
                    }
                default://"String"
                    return new ColumnType(typeof(String));
            }
        }
    }
}

wizardzz wrote:

I do not understand the downvote here.