I have an application that runs with and without a GUI depending on the user. I need it to export the DataGrid as a CSV file, heres the code:
// Copy contents of datagrid to clipboard, including header.
mainDataGrid.SelectAllCells();
mainDataGrid.ClipboardCopyMode = DataGridClipboardCopyMode.IncludeHeader;
ApplicationCommands.Copy.Execute(null, mainDataGrid);
string result = (string)Clipboard.GetData(DataFormats.CommaSeparatedValue);
This works fine with the GUI. The problem happens when I don't have a GUI, I think this is because the clipboard can't copy something that isn't there. Is there a different way to export it or is there a way to set the clipboards data instead of executing a copy command?
In order to "copy something that isn't there", you'll need to use the underlying data object that is your DataGrid's ItemsSource.
If your DataGrid's ItemsSource is a DataTable, this method, analogous to MosesTheHoly's, will return a CSV string, but in a simpler manner.
public string GetCSVFromDataTabe(DataTable datatable)
{
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.Append(string.Join(",", dt.Columns.ToList<DataColumn>().Select(column => column.ColumnName).ToList()) + "\n");
dataTable.Rows.ToList<DataRow>().ForEach(row => sb.Append(string.Join(",", row.ItemArray) + "\n"));
return stringBuilder.ToString();
}
That should do it. Fairly concise, in my opinion. Now, just write that string to whatever file you need.
Alright, the code could probably be shortened, but this is the way I did it. I created a function that takes in a datatable and returns a CSV string.
private void SaveToCSV() {
DataTable dt = new DataTable();
dt = ((DataView)mainDataGrid.ItemsSource).ToTable();
string result = WriteDataTable(dt);
// The File.Create().Close() is so it closes the filestream after it creates it.
if (!File.Exists(CSVFilePath)) {
File.Create(CSVFilePath).Close();
}
File.AppendAllText(CSVFilePath, result, UnicodeEncoding.UTF8);
}
private string WriteDataTable(DataTable dataTable) {
string output = "";
// Need to get the last column so I know when to add a new line instead of comma.
string lastColumnName = dataTable.Columns[dataTable.Columns.Count - 1].ColumnName;
// Get the headers from the datatable.
foreach (DataColumn column in dataTable.Columns) {
if (lastColumnName != column.ColumnName) {
output += (column.ColumnName.ToString() + ",");
}
else {
output += (column.ColumnName.ToString() + "\n");
}
}
// Get the actual data from the datatable.
foreach (DataRow row in dataTable.Rows) {
foreach (DataColumn column in dataTable.Columns) {
if (lastColumnName != column.ColumnName) {
output += (row[column].ToString() + ",");
}
else {
output += (row[column].ToString() + "\n");
}
}
}
return output;
}
I'm building a csv file from database values. When I open the csv in excel everything is on one row. To counter this I've added either \n or \r after each row. Now when I open in excel starting at the second row there is an empty value throughout the rest of the first column.
IE:
value 1, value 2, value 3
, value 1, value 2, value 3
, value 1, value 2, value 3
, value 1, value 2, value 3
I can add a newline or return before the first value, but then there is an empty row and column. How can I get this lined up?
My code:
try
{
connection = new iDB2Connection(connectionString);
connection.Open();
command = new iDB2Command(commandString, connection);
reader = command.ExecuteReader();
var dt = new DataTable();
dt.Load(reader);
List<string> CsvList = new List<string>();
foreach (DataRow row in dt.Rows)
{
foreach (var item in row.ItemArray)
{
CsvList.Add(item.ToString());
}
if (i == 1)
{
CsvList.Add(" ");
CsvList.Add("Customer Service");
CsvList.Add("Customer Service Representative" + "\r");
// \r and \n not working
}
}
System.IO.StreamWriter streamWriter;
streamWriter = new System.IO.StreamWriter(fileName, true);
string CsvString = string.Join(",", CsvList.ToArray());
streamWriter.WriteLine(CsvString);
streamWriter.Close();
Console.WriteLine("File saved as " + fileName);
i++;
}
It'll be a heck of a lot easier if you just build up a list of lines, rather than a flattened list of single values. Since you've flattened your list already when you use Join you're putting commas after newlines values, for example.
Instead join together the values for each line, and then just keep track of the entire lines:
foreach (DataRow row in dt.Rows)
{
CsvList.Add(string.Join(",", row.ItemArray));
}
Now that you have a list of lines, we can just use File.AppendAllLines to simply and easily write out all of the lines to the end of the file:
File.AppendAllLines(fileName, CsvList);
Or, if you would like to stream the results to the file rather than copying all of the data over to a list and holding it all in memory at once, you can do this:
var lines = dt.AsEnumerable()
.Select(row => string.Join(",", row.ItemArray));
File.AppendAllLines(fileName, lines);
Instead of creating an array and handling adding new-lines yourself, use a StringBuilder, and commit each row one at a time:
var sb = new StringBuilder();
foreach (DataRow row in dt.Rows)
{
List<string> csvList = new List<string>();
foreach (var item in row.ItemArray)
{
csvList.Add(item.ToString());
}
if (i == 1)
{
csvList.Add(" ");
csvList.Add("Customer Service");
csvList.Add("Customer Service Representative");
}
sb.WriteLine(string.Join(",", csvList));
}
System.IO.StreamWriter streamWriter;
streamWriter = new System.IO.StreamWriter(fileName, true);
streamWriter.WriteLine(sb.ToString());
streamWriter.Close();
Console.WriteLine("File saved as " + fileName);
I'm working on a application which will export my DataGridView called scannerDataGridView to a csv file.
Found some example code to do this, but can't get it working. Btw my datagrid isn't databound to a source.
When i try to use the Streamwriter to only write the column headers everything goes well, but when i try to export the whole datagrid including data i get an exeption trhown.
System.NullReferenceException: Object reference not set to an instance
of an object. at Scanmonitor.Form1.button1_Click(Object sender,
EventArgs e)
Here is my Code, error is given on the following line:
dataFromGrid = dataFromGrid + ',' + dataRowObject.Cells[i].Value.ToString();
//csvFileWriter = StreamWriter
//scannerDataGridView = DataGridView
private void button1_Click(object sender, EventArgs e)
{
string CsvFpath = #"C:\scanner\CSV-EXPORT.csv";
try
{
System.IO.StreamWriter csvFileWriter = new StreamWriter(CsvFpath, false);
string columnHeaderText = "";
int countColumn = scannerDataGridView.ColumnCount - 1;
if (countColumn >= 0)
{
columnHeaderText = scannerDataGridView.Columns[0].HeaderText;
}
for (int i = 1; i <= countColumn; i++)
{
columnHeaderText = columnHeaderText + ',' + scannerDataGridView.Columns[i].HeaderText;
}
csvFileWriter.WriteLine(columnHeaderText);
foreach (DataGridViewRow dataRowObject in scannerDataGridView.Rows)
{
if (!dataRowObject.IsNewRow)
{
string dataFromGrid = "";
dataFromGrid = dataRowObject.Cells[0].Value.ToString();
for (int i = 1; i <= countColumn; i++)
{
dataFromGrid = dataFromGrid + ',' + dataRowObject.Cells[i].Value.ToString();
csvFileWriter.WriteLine(dataFromGrid);
}
}
}
csvFileWriter.Flush();
csvFileWriter.Close();
}
catch (Exception exceptionObject)
{
MessageBox.Show(exceptionObject.ToString());
}
LINQ FTW!
var sb = new StringBuilder();
var headers = dataGridView1.Columns.Cast<DataGridViewColumn>();
sb.AppendLine(string.Join(",", headers.Select(column => "\"" + column.HeaderText + "\"").ToArray()));
foreach (DataGridViewRow row in dataGridView1.Rows)
{
var cells = row.Cells.Cast<DataGridViewCell>();
sb.AppendLine(string.Join(",", cells.Select(cell => "\"" + cell.Value + "\"").ToArray()));
}
And indeed, c.Value.ToString() will throw on null value, while c.Value will correctly convert to an empty string.
A little known feature of the DataGridView is the ability to programmatically select some or all of the DataGridCells, and send them to a DataObject using the method DataGridView.GetClipboardContent(). Whats the advantage of this then?
A DataObject doesn't just store an object, but rather the representation of that object in various different formats. This is how the Clipboard is able to work its magic; it has various formats stored and different controls/classes can specify which format they wish to accept. In this case, the DataGridView will store the selected cells in the DataObject as a tab-delimited text format, a CSV format, or as HTML (*).
The contents of the DataObject can be retrieved by calling the DataObject.GetData() or DataObject.GetText() methods and specifying a predefined data format enum. In this case, we want the format to be TextDataFormat.CommaSeparatedValue for CSV, then we can just write that result to a file using System.IO.File class.
(*) Actually, what it returns is not, strictly speaking, HTML. This format will also contain a data header that you were not expecting. While the header does contain the starting position of the HTML, I just discard anything above the HTML tag like myString.Substring(IndexOf("<HTML>"));.
Observe the following code:
void SaveDataGridViewToCSV(string filename)
{
// Choose whether to write header. Use EnableWithoutHeaderText instead to omit header.
dataGridView1.ClipboardCopyMode = DataGridViewClipboardCopyMode.EnableAlwaysIncludeHeaderText;
// Select all the cells
dataGridView1.SelectAll();
// Copy selected cells to DataObject
DataObject dataObject = dataGridView1.GetClipboardContent();
// Get the text of the DataObject, and serialize it to a file
File.WriteAllText(filename, dataObject.GetText(TextDataFormat.CommaSeparatedValue));
}
Now, isn't that better? Why re-invent the wheel?
Hope this helps...
Please check this code.its working fine
try
{
//Build the CSV file data as a Comma separated string.
string csv = string.Empty;
//Add the Header row for CSV file.
foreach (DataGridViewColumn column in dataGridView1.Columns)
{
csv += column.HeaderText + ',';
}
//Add new line.
csv += "\r\n";
//Adding the Rows
foreach (DataGridViewRow row in dataGridView1.Rows)
{
foreach (DataGridViewCell cell in row.Cells)
{
if (cell.Value != null)
{
//Add the Data rows.
csv += cell.Value.ToString().TrimEnd(',').Replace(",", ";") + ',';
}
// break;
}
//Add new line.
csv += "\r\n";
}
//Exporting to CSV.
string folderPath = "C:\\CSV\\";
if (!Directory.Exists(folderPath))
{
Directory.CreateDirectory(folderPath);
}
File.WriteAllText(folderPath + "Invoice.csv", csv);
MessageBox.Show("");
}
catch
{
MessageBox.Show("");
}
Found the problem, the coding was fine but i had an empty cell that gave the problem.
Your code was almost there... But I made the following corrections and it works great. Thanks for the post.
Error:
string[] output = new string[dgvLista_Apl_Geral.RowCount + 1];
Correction:
string[] output = new string[DGV.RowCount + 1];
Error:
System.IO.File.WriteAllLines(filename, output, System.Text.Encoding.UTF8);
Correction:
System.IO.File.WriteAllLines(sfd.FileName, output, System.Text.Encoding.UTF8);
The line "csvFileWriter.WriteLine(dataFromGrid);" should be moved down one line below the closing bracket, else you'll get a lot of repeating results:
for (int i = 1; i <= countColumn; i++)
{
dataFromGrid = dataFromGrid + ',' + dataRowObject.Cells[i].Value.ToString();
}
csvFileWriter.WriteLine(dataFromGrid);
I think this is the correct for your SaveToCSV function : ( otherwise Null ...)
for (int i = 0; i < columnCount; i++)
Not :
for (int i = 1; (i - 1) < DGV.RowCount; i++)
This is what I been using in my projects:
void export_csv(string file, DataGridView grid)
{
using (StreamWriter csv = new StreamWriter(file, false))
{
int totalcolms = grid.ColumnCount;
foreach (DataGridViewColumn colm in grid.Columns) csv.Write(colm.HeaderText + ',');
csv.Write('\n');
string data = "";
foreach (DataGridViewRow row in grid.Rows)
{
if (row.IsNewRow) continue;
data = "";
for (int i = 0; i < totalcolms; i++)
{
data += (row.Cells[i].Value ?? "").ToString() + ',';
}
if (data != string.Empty) csv.WriteLine(data);
}
}
}
Could somebody please tell me why the following code is not working. The data is saved into the csv file, however the data is not separated. It all exists within the first cell of each row.
StringBuilder sb = new StringBuilder();
foreach (DataColumn col in dt.Columns)
{
sb.Append(col.ColumnName + ',');
}
sb.Remove(sb.Length - 1, 1);
sb.Append(Environment.NewLine);
foreach (DataRow row in dt.Rows)
{
for (int i = 0; i < dt.Columns.Count; i++)
{
sb.Append(row[i].ToString() + ",");
}
sb.Append(Environment.NewLine);
}
File.WriteAllText("test.csv", sb.ToString());
Thanks.
The following shorter version opens fine in Excel, maybe your issue was the trailing comma
.net = 3.5
StringBuilder sb = new StringBuilder();
string[] columnNames = dt.Columns.Cast<DataColumn>().
Select(column => column.ColumnName).
ToArray();
sb.AppendLine(string.Join(",", columnNames));
foreach (DataRow row in dt.Rows)
{
string[] fields = row.ItemArray.Select(field => field.ToString()).
ToArray();
sb.AppendLine(string.Join(",", fields));
}
File.WriteAllText("test.csv", sb.ToString());
.net >= 4.0
And as Tim pointed out, if you are on .net>=4, you can make it even shorter:
StringBuilder sb = new StringBuilder();
IEnumerable<string> columnNames = dt.Columns.Cast<DataColumn>().
Select(column => column.ColumnName);
sb.AppendLine(string.Join(",", columnNames));
foreach (DataRow row in dt.Rows)
{
IEnumerable<string> fields = row.ItemArray.Select(field => field.ToString());
sb.AppendLine(string.Join(",", fields));
}
File.WriteAllText("test.csv", sb.ToString());
As suggested by Christian, if you want to handle special characters escaping in fields, replace the loop block by:
foreach (DataRow row in dt.Rows)
{
IEnumerable<string> fields = row.ItemArray.Select(field =>
string.Concat("\"", field.ToString().Replace("\"", "\"\""), "\""));
sb.AppendLine(string.Join(",", fields));
}
And last suggestion, you could write the csv content line by line instead of as a whole document, to avoid having a big document in memory.
I wrapped this up into an extension class, which allows you to call:
myDataTable.WriteToCsvFile("C:\\MyDataTable.csv");
on any DataTable.
public static class DataTableExtensions
{
public static void WriteToCsvFile(this DataTable dataTable, string filePath)
{
StringBuilder fileContent = new StringBuilder();
foreach (var col in dataTable.Columns)
{
fileContent.Append(col.ToString() + ",");
}
fileContent.Replace(",", System.Environment.NewLine, fileContent.Length - 1, 1);
foreach (DataRow dr in dataTable.Rows)
{
foreach (var column in dr.ItemArray)
{
fileContent.Append("\"" + column.ToString() + "\",");
}
fileContent.Replace(",", System.Environment.NewLine, fileContent.Length - 1, 1);
}
System.IO.File.WriteAllText(filePath, fileContent.ToString());
}
}
A new extension function based on Paul Grimshaw's answer. I cleaned it up and added the ability to handle unexpected data. (Empty Data, Embedded Quotes, and comma's in the headings...)
It also returns a string which is more flexible. It returns Null if the table object does not contain any structure.
public static string ToCsv(this DataTable dataTable) {
StringBuilder sbData = new StringBuilder();
// Only return Null if there is no structure.
if (dataTable.Columns.Count == 0)
return null;
foreach (var col in dataTable.Columns) {
if (col == null)
sbData.Append(",");
else
sbData.Append("\"" + col.ToString().Replace("\"", "\"\"") + "\",");
}
sbData.Replace(",", System.Environment.NewLine, sbData.Length - 1, 1);
foreach (DataRow dr in dataTable.Rows) {
foreach (var column in dr.ItemArray) {
if (column == null)
sbData.Append(",");
else
sbData.Append("\"" + column.ToString().Replace("\"", "\"\"") + "\",");
}
sbData.Replace(",", System.Environment.NewLine, sbData.Length - 1, 1);
}
return sbData.ToString();
}
You call it as follows:
var csvData = dataTableOject.ToCsv();
If your calling code is referencing the System.Windows.Forms assembly, you may consider a radically different approach.
My strategy is to use the functions already provided by the framework to accomplish this in very few lines of code and without having to loop through columns and rows. What the code below does is programmatically create a DataGridView on the fly and set the DataGridView.DataSource to the DataTable. Next, I programmatically select all the cells (including the header) in the DataGridView and call DataGridView.GetClipboardContent(), placing the results into the Windows Clipboard. Then, I 'paste' the contents of the clipboard into a call to File.WriteAllText(), making sure to specify the formatting of the 'paste' as TextDataFormat.CommaSeparatedValue.
Here is the code:
public static void DataTableToCSV(DataTable Table, string Filename)
{
using(DataGridView dataGrid = new DataGridView())
{
// Save the current state of the clipboard so we can restore it after we are done
IDataObject objectSave = Clipboard.GetDataObject();
// Set the DataSource
dataGrid.DataSource = Table;
// Choose whether to write header. Use EnableWithoutHeaderText instead to omit header.
dataGrid.ClipboardCopyMode = DataGridViewClipboardCopyMode.EnableAlwaysIncludeHeaderText;
// Select all the cells
dataGrid.SelectAll();
// Copy (set clipboard)
Clipboard.SetDataObject(dataGrid.GetClipboardContent());
// Paste (get the clipboard and serialize it to a file)
File.WriteAllText(Filename,Clipboard.GetText(TextDataFormat.CommaSeparatedValue));
// Restore the current state of the clipboard so the effect is seamless
if(objectSave != null) // If we try to set the Clipboard to an object that is null, it will throw...
{
Clipboard.SetDataObject(objectSave);
}
}
}
Notice I also make sure to preserve the contents of the clipboard before I begin, and restore it once I'm done, so the user does not get a bunch of unexpected garbage next time the user tries to paste. The main caveats to this approach is 1) Your class has to reference System.Windows.Forms, which may not be the case in a data abstraction layer, 2) Your assembly will have to be targeted for .NET 4.5 framework, as DataGridView does not exist in 4.0, and 3) The method will fail if the clipboard is being used by another process.
Anyways, this approach may not be right for your situation, but it is interesting none the less, and can be another tool in your toolbox.
I did this recently but included double quotes around my values.
For example, change these two lines:
sb.Append("\"" + col.ColumnName + "\",");
...
sb.Append("\"" + row[i].ToString() + "\",");
Try changing sb.Append(Environment.NewLine); to sb.AppendLine();.
StringBuilder sb = new StringBuilder();
foreach (DataColumn col in dt.Columns)
{
sb.Append(col.ColumnName + ',');
}
sb.Remove(sb.Length - 1, 1);
sb.AppendLine();
foreach (DataRow row in dt.Rows)
{
for (int i = 0; i < dt.Columns.Count; i++)
{
sb.Append(row[i].ToString() + ",");
}
sb.AppendLine();
}
File.WriteAllText("test.csv", sb.ToString());
4 lines of code:
public static string ToCSV(DataTable tbl)
{
StringBuilder strb = new StringBuilder();
//column headers
strb.AppendLine(string.Join(",", tbl.Columns.Cast<DataColumn>()
.Select(s => "\"" + s.ColumnName + "\"")));
//rows
tbl.AsEnumerable().Select(s => strb.AppendLine(
string.Join(",", s.ItemArray.Select(
i => "\"" + i.ToString() + "\"")))).ToList();
return strb.ToString();
}
Note that the ToList() at the end is important; I need something to force an expression evaluation. If I was code golfing, I could use Min() instead.
Also note that the result will have a newline at the end because of the last call to AppendLine(). You may not want this. You can simply call TrimEnd() to remove it.
Try to put ; instead of ,
Hope it helps
The error is the list separator.
Instead of writing sb.Append(something... + ',') you should put something like sb.Append(something... + System.Globalization.CultureInfo.CurrentCulture.TextInfo.ListSeparator);
You must put the list separator character configured in your operating system (like in the example above), or the list separator in the client machine where the file is going to be watched. Another option would be to configure it in the app.config or web.config as a parammeter of your application.
To write to a file, I think the following method is the most efficient and straightforward: (You can add quotes if you want)
public static void WriteCsv(DataTable dt, string path)
{
using (var writer = new StreamWriter(path)) {
writer.WriteLine(string.Join(",", dt.Columns.Cast<DataColumn>().Select(dc => dc.ColumnName)));
foreach (DataRow row in dt.Rows) {
writer.WriteLine(string.Join(",", row.ItemArray));
}
}
}
Read this and this?
A better implementation would be
var result = new StringBuilder();
for (int i = 0; i < table.Columns.Count; i++)
{
result.Append(table.Columns[i].ColumnName);
result.Append(i == table.Columns.Count - 1 ? "\n" : ",");
}
foreach (DataRow row in table.Rows)
{
for (int i = 0; i < table.Columns.Count; i++)
{
result.Append(row[i].ToString());
result.Append(i == table.Columns.Count - 1 ? "\n" : ",");
}
}
File.WriteAllText("test.csv", result.ToString());
To mimic Excel CSV:
public static string Convert(DataTable dt)
{
StringBuilder sb = new StringBuilder();
IEnumerable<string> columnNames = dt.Columns.Cast<DataColumn>().
Select(column => column.ColumnName);
sb.AppendLine(string.Join(",", columnNames));
foreach (DataRow row in dt.Rows)
{
IEnumerable<string> fields = row.ItemArray.Select(field =>
{
string s = field.ToString().Replace("\"", "\"\"");
if(s.Contains(','))
s = string.Concat("\"", s, "\"");
return s;
});
sb.AppendLine(string.Join(",", fields));
}
return sb.ToString().Trim();
}
Here is an enhancement to vc-74's post that handles commas the same way Excel does. Excel puts quotes around data if the data has a comma but doesn't quote if the data doesn't have a comma.
public static string ToCsv(this DataTable inDataTable, bool inIncludeHeaders = true)
{
var builder = new StringBuilder();
var columnNames = inDataTable.Columns.Cast<DataColumn>().Select(column => column.ColumnName);
if (inIncludeHeaders)
builder.AppendLine(string.Join(",", columnNames));
foreach (DataRow row in inDataTable.Rows)
{
var fields = row.ItemArray.Select(field => field.ToString().WrapInQuotesIfContains(","));
builder.AppendLine(string.Join(",", fields));
}
return builder.ToString();
}
public static string WrapInQuotesIfContains(this string inString, string inSearchString)
{
if (inString.Contains(inSearchString))
return "\"" + inString+ "\"";
return inString;
}
Here is my solution, based on previous answers by Paul Grimshaw and Anthony VO.
I've submitted the code in a C# project on Github.
My main contribution is to eliminate explicitly creating and manipulating a StringBuilder and instead working only with IEnumerable. This avoids the allocation of a big buffer in memory.
public static class Util
{
public static string EscapeQuotes(this string self) {
return self?.Replace("\"", "\"\"") ?? "";
}
public static string Surround(this string self, string before, string after) {
return $"{before}{self}{after}";
}
public static string Quoted(this string self, string quotes = "\"") {
return self.Surround(quotes, quotes);
}
public static string QuotedCSVFieldIfNecessary(this string self)
{
return (self == null) ? "" : (self.Contains('"') || self.Contains('\r') || self.Contains('\n') || self.Contains(',')) ? self.Quoted() : self;
}
public static string ToCsvField(this string self) {
return self.EscapeQuotes().QuotedCSVFieldIfNecessary();
}
public static string ToCsvRow(this IEnumerable<string> self){
return string.Join(",", self.Select(ToCsvField));
}
public static IEnumerable<string> ToCsvRows(this DataTable self) {
yield return self.Columns.OfType<object>().Select(c => c.ToString()).ToCsvRow();
foreach (var dr in self.Rows.OfType<DataRow>())
yield return dr.ItemArray.Select(item => item.ToString()).ToCsvRow();
}
public static void ToCsvFile(this DataTable self, string path) {
File.WriteAllLines(path, self.ToCsvRows());
}
}
This approach combines nicely with converting IEnumerable to DataTable as asked here.
StringBuilder sb = new StringBuilder();
SaveFileDialog fileSave = new SaveFileDialog();
IEnumerable<string> columnNames = tbCifSil.Columns.Cast<DataColumn>().
Select(column => column.ColumnName);
sb.AppendLine(string.Join(",", columnNames));
foreach (DataRow row in tbCifSil.Rows)
{
IEnumerable<string> fields = row.ItemArray.Select(field =>string.Concat("\"", field.ToString().Replace("\"", "\"\""), "\""));
sb.AppendLine(string.Join(",", fields));
}
fileSave.ShowDialog();
File.WriteAllText(fileSave.FileName, sb.ToString());
public void ExpoetToCSV(DataTable dtDataTable, string strFilePath)
{
StreamWriter sw = new StreamWriter(strFilePath, false);
//headers
for (int i = 0; i < dtDataTable.Columns.Count; i++)
{
sw.Write(dtDataTable.Columns[i].ToString().Trim());
if (i < dtDataTable.Columns.Count - 1)
{
sw.Write(",");
}
}
sw.Write(sw.NewLine);
foreach (DataRow dr in dtDataTable.Rows)
{
for (int i = 0; i < dtDataTable.Columns.Count; i++)
{
if (!Convert.IsDBNull(dr[i]))
{
string value = dr[i].ToString().Trim();
if (value.Contains(','))
{
value = String.Format("\"{0}\"", value);
sw.Write(value);
}
else
{
sw.Write(dr[i].ToString().Trim());
}
}
if (i < dtDataTable.Columns.Count - 1)
{
sw.Write(",");
}
}
sw.Write(sw.NewLine);
}
sw.Close();
}
Possibly, most easy way will be to use:
https://github.com/ukushu/DataExporter
especially in case of your data of datatable containing /r/n characters or separator symbol inside of your dataTable cells. Almost all of other answers will not work with such cells.
only you need is to write the following code:
Csv csv = new Csv("\t");//Needed delimiter
var columnNames = dt.Columns.Cast<DataColumn>().
Select(column => column.ColumnName).ToArray();
csv.AddRow(columnNames);
foreach (DataRow row in dt.Rows)
{
var fields = row.ItemArray.Select(field => field.ToString()).ToArray;
csv.AddRow(fields);
}
csv.Save();
Most existing answers can easily cause OutOfMemoryException, so I decided to write my own answer.
DON' T DO THIS:
using a DataSet + StringBuilder causes the data to occupy the memory 3x at once:
Load All Data into DataSet
Copy all data into StringBuilder
Copy the data to string using StringBuilder.ToString();
Instead you should write each row to a FileStream separately. There is no need to create the whole CSV in memory.
Even better, use a DataReader instead DataSet. That way you can read from database billions of records one by one a write the to a file one by one.
If you don't mind using an external library for CSV, I can recommend the most popular CsvHelper, which has no dependencies.
using (var writer = new FileWriter("test.csv"))
using (var csv = new CsvWriter(writer, CultureInfo.InvariantCulture))
{
foreach (DataColumn dc in dt.Columns)
{
csv.WriteField(dc.ColumnName);
}
csv.NextRecord();
foreach (DataRow dr in dt.Rows)
{
foreach (DataColumn dc in dt.Columns)
{
csv.WriteField(dr[dc]);
}
csv.NextRecord();
}
writer.ToString().Dump();
}
In case anyone else stumbles on this, I was using File.ReadAllText to get CSV data and then I modified it and wrote it back with File.WriteAllText. The \r\n CRLFs were fine but the \t tabs were ignored when Excel opened it. (All solutions in this thread so far use a comma delimiter but that doesn't matter.) Notepad showed the same format in the resulting file as in the source. A Diff even showed the files as identical. But I got a clue when I opened the file in Visual Studio with a binary editor. The source file was Unicode but the target was ASCII. To fix, I modified both ReadAllText and WriteAllText with third argument set as System.Text.Encoding.Unicode, and from there Excel was able to open the updated file.