I use this code to write into a text file in my code behinde:
string filePath = HttpContext.Current.Server.MapPath("s.txt");
if (File.Exists(filePath))
{
StreamWriter writer = new StreamWriter(filePath, true);
string logMessage = "ok";
writer.WriteLine(logMessage);
writer.Flush();
writer.Close();
}
how i can clear all data in this text file before writeing into this file?
You are using the constructor that instructs the stream to Append to the existing file (or create a new one if it doesn't exist. Just change your constructor to
using(StreamWriter writer = new StreamWriter(filePath, false))
{
.....
}
and it will clear and rewrite your file
MSDN says about the second parameter
appendType: System.Boolean
true to append data to the file; false to overwrite the file. If the
specified file does not exist, this parameter has no effect, and the
constructor creates a new file.
Notice also that you should use the using statement around a Stream to be sure to properly close and dispose the underlying file system resource.
You should be using false as your 2nd parameter instead of true.
StreamWriter writer = new StreamWriter(filePath, false);
True indicates to append the text to the file.
Alternatively, you can also use the following code to remove all text from a file
File.WriteAllText(filePath, String.Empty);
Related
I want to offer users of my application to download a docx file which would contain dynamic content depending on their request.
I prepared a template with header, otherwise the OpenXML creation is pain in the somewhere.
Now I am having trouble with editing it and returning it as FileResult in my ASP MVC application.
My plan is to read a file to MemoryStream and edit it as WordprocessingDocument and then returning MemoryStream as Byte[].
I have two problems here:
If I read WordprocessingDocument directly from file without memory stream, I don't see a way to transform it to the shape FileResult() wants.
If I create new WordprocessingDocument with empty MemoryStream I can simply create content and return it as File but I lack the previously prepared header with desired content.
So, how to edit a .docx template and return it as FileResult()?
This is how you go about creating a new spreadsheet document with MemoryStream and then saving it to a Byte[]
Byte[] file;
using (MemoryStream mem = new MemoryStream())
{
using (SpreadsheetDocument spreadsheetDocument =
SpreadsheetDocument.Create(mem, SpreadsheetDocumentType.Workbook))
{
WorkbookPart workbookpart = spreadsheetDocument.AddWorkbookPart();
workbookpart.Workbook = new Workbook();
WorksheetPart worksheetPart = workbookpart.AddNewPart<WorksheetPart>();
worksheetPart.Worksheet = new Worksheet(new SheetData());
Sheets sheets = spreadsheetDocument.WorkbookPart.Workbook.
AppendChild<Sheets>(new Sheets());
Sheet sheet = new Sheet()
{
Id = spreadsheetDocument.WorkbookPart.
GetIdOfPart(worksheetPart),
SheetId = 1,
Name = "aStupidSheet"
};
sheets.Append(sheet);
workbookpart.Workbook.Save()
spreadsheetDocument.Close();
}
file = mem.ToArray();
}
With the help from FortyTwo I managed to achieve my goal.
So the desired "workflow" is:
copy .docx template (added headers or other things) to memory
edit content of the document
return this document as FileResult without saving the changes to template
So here is the code:
public FileResult EditDOCXBody()
{
// Prepare file path
string file = "../WordTemplates/EmptyTemplate.docx";
String fullFilePath = HttpContext.ApplicationInstance.Server.MapPath(file);
// Copy file content to MemeoryStream via byte array
MemoryStream stream = new MemoryStream();
byte[] fileBytesArray = System.IO.File.ReadAllBytes(fullFilePath);
stream.Write(fileBytesArray, 0, fileBytesArray.Length); // copy file content to MemoryStream
stream.Position = 0;
// Edit word document content
using (WordprocessingDocument wordDoc = WordprocessingDocument.Open(stream, true))
{
MainDocumentPart mainPart = wordDoc.MainDocumentPart;
Body body = mainPart.Document.Body;
// add some text to body
body.Append(new Paragraph(
new Run(
new Text("Current time is: " + DateTime.Now.ToLongTimeString()))));
// Save changes to reflect on stream object
mainPart.Document.Save();
}
return File(stream.ToArray(), "application/vnd.openxmlformats-officedocument.wordprocessingml.document", "servedFilename.docx");
}
Some important notes:
you need to write file bytes to MemoryStream manually otherwise you get Memory stream is not expandable error. More info here
you have to use mainPart.Document.Save() for changes to take effect on MemoryStream
when returning the file, you have to use .ToArray() otherwise the returned file is corrupted
I am required to replace a word in an existing PDF AcroField with another word. I am using PDFStamper of iTEXTSHARP to do the same and it is working fine. But, in doing so it is required to create a new PDF and i would like the change to be reflected in the existing PDF itself. If I am setting the destination filename same as the original filename then no change is being reflected.I am new to iTextSharp , is there anything I am doing wrong? Please help.. I am providing the piece of code I am using
private void ListFieldNames(string s)
{
try
{
string pdfTemplate = #"z:\TEMP\PDF\PassportApplicationForm_Main_English_V1.0.pdf";
string newFile = #"z:\TEMP\PDF\PassportApplicationForm_Main_English_V1.0.pdf";
PdfReader pdfReader = new PdfReader(pdfTemplate);
for (int page = 1; page <= pdfReader.NumberOfPages; page++)
{
PdfReader reader = new PdfReader((string)pdfTemplate);
using (PdfStamper stamper = new PdfStamper(reader, new FileStream(newFile, FileMode.Create, FileAccess.ReadWrite)))
{
AcroFields form = stamper.AcroFields;
var fieldKeys = form.Fields.Keys;
foreach (string fieldKey in fieldKeys)
{
//Replace Address Form field with my custom data
if (fieldKey.Contains("Address"))
{
form.SetField(fieldKey, s);
}
}
stamper.FormFlattening = true;
stamper.Close();
}
}
}
As documented in my book iText in Action, you can't read a file and write to it simultaneously. Think of how Word works: you can't open a Word document and write directly to it. Word always creates a temporary file, writes the changes to it, then replaces the original file with it and then throws away the temporary file.
You can do that too:
read the original file with PdfReader,
create a temporary file for PdfStamper, and when you're done,
replace the original file with the temporary file.
Or:
read the original file into a byte[],
create PdfReader with this byte[], and
use the path to the original file for PdfStamper.
This second option is more dangerous, as you'll lose the original file if you do something that causes an exception in PdfStamper.
I have a controller action declared as follows:
[Authorize(Order = 0, Roles = "Requester,Controller,Installer")]
public FileStreamResult ExportJobCards()
The body of this method builds a collection of CSV lines, and attempts to return them as a file as follows:
using (var sw = new StreamWriter(new MemoryStream()))
{
foreach (var line in lines)
{
sw.WriteLine(line);
}
return new FileStreamResult(sw.BaseStream, "text/csv");
}
When I request this action using the following action link...
Html.ActionLink("Export to Excel", "ExportJobCards")
...the export method executes properly, i.e. all the required CSV data is present in the lines collection in the above code, but I get a File Not Found error rendered as the end result.
EDIT:
In agreement with Tommy's observation, I moved the return out of the using, and I now get a file, but the file is empty. The new code that actually produces a file, ableit empty, is:
var sw = new StreamWriter(new MemoryStream());
foreach (var line in lines)
{
sw.WriteLine(line);
}
sw.Flush();
return new FileStreamResult(sw.BaseStream, "text/csv");
With your current setup, the Using statement is disposing of the StringWriter before the return can complete, which is resulting in the null reference/file not found error. Remove the using statement or set the StringWriter to another variable before you exit out and you should be good to go on getting rid of the File Not Found error.
A thought on your second issue now, looking into memorystreams as filestream results, you may need to change your return to this
sw.BaseStream.seek(0, SeekOrigin.Begin)
return new FileStreamResult(sw.BaseStream, "text/csv");
as the pointer is still at the end of the stream when you return.
It throws that error because you're not giving it a file stream. What you want is the FileContentResult into which you can pass arbitrary content. This content needs to be a byte array of your content, probably easiest to:
use a stringbuilder rather than a streamwriter
get your string from the builder
use the static method System.Text.UnicodeEncoding.Unicode.GetBytes(string) to get the byte array
Give the byte array to FileContentResult
As you have to write this code anyway the easiest thing to do would be to create a new FileStringResult that inherits from the base FileResult that can take in a string or stringbuilder. Override WriteFile(HttpResponseBase response) to do the string to byte[] conversion and push that into the response. Take a look at the FileStreamResult class from the MVC sources, it's very small and easy to do.
Consider:
strPath= c:\images\gallery\add.gif
I need to rename this file from add.gif to thumb1.gid, and I should write one command method, whatever the file name. We need to
replace that name with this like below.
string strfilename = **"thumb"**
****Result thum.gif**
strPath= c:\images\gallery\thum.gif **
You have several problems, looking up the value in the XML file, and renaming the file.
To look up the number corresponding to Gallery2 or whatever, I would recommend having a look at Stack Overflow question How to implement a simple XPath lookup which explains how to look up nodes/values in an XML file.
To rename a file in .NET, use something like this:
using System.IO;
FileInfo fi = new FileInfo("c:\\images\\gallery\\add.gif");
if (fi.Exists)
{
fi.MoveTo("c:\\images\\gallery\\thumb3.gif");
}
Of course, you would use string variables instead of string literals for the paths.
That should give you enough information to piece it together and solve your particular lookup-rename problem.
I created a utility method to help encapsulate how to rename a file.
public class FileUtilities
{
public static void RenameFile(string oldFilenameWithPathWithExtension, string newFilenameWithoutPathWithExtension)
{
try
{
string directoryPath = Path.GetDirectoryName(oldFilenameWithPathWithExtension);
if (directoryPath == null)
{
throw new Exception($"Directory not found in given path value:{oldFilenameWithPathWithExtension}");
}
var newFilenameWithPath = Path.Combine(directoryPath, newFilenameWithoutPathWithExtension);
FileInfo fileInfo = new FileInfo(oldFilenameWithPathWithExtension);
fileInfo.MoveTo(newFilenameWithPath);
}
catch (Exception e)
{
//Boiler plate exception handling
Console.WriteLine(e);
throw;
}
}
}
I omitted several other file system checks that could optionally be done, but as #JoelCoehoorn pointed out in a comment on this page, the File System is Volatile, so wrapping it in a try-catch may be all that is necessary.
With that class in your library, now you can simply call:
var fullFilename = #"C:\images\gallery\add.gif";
var newFilename = "Thumb.gif";
FileHelper.RenameFile(fullFilename,newFilename);
I have an XML file which is being uploaded to an ASP.Net page via the normal file upload control. When it gets up, I am attempting to validate and deserialize the XML. However, the code below is really very handy for validating an XML file which references it's XSD like this:
xsi:schemaLocation="someurl ..\localSchemaPath.xsd"
However, if I upload this XML file, only the XML file gets uploaded, so ..\localSchemaPath.xsd doesn't exist, so it can't validate.
Even if I stored the XSD locally, it still wouldn't be quite right as the XML file could be written with a schema location like:
xsi:schemaLocation="someurl ..\localSchemaPath.xsd"
or
xsi:schemaLocation="someurl localSchemaPath.xsd"
or
xsi:schemaLocation="someurl ..................\localSchemaPath.xsd"
if it so wished.
Dilemma!
(For the purposes of this question, I have pinched the code below from: Validating an XML against referenced XSD in C#)
using System.Xml;
using System.Xml.Schema;
using System.IO;
public class ValidXSD
{
public static void Main()
{
// Set the validation settings.
XmlReaderSettings settings = new XmlReaderSettings();
settings.ValidationType = ValidationType.Schema;
settings.ValidationFlags |= XmlSchemaValidationFlags.ProcessInlineSchema;
settings.ValidationFlags |= XmlSchemaValidationFlags.ProcessSchemaLocation;
settings.ValidationFlags |= XmlSchemaValidationFlags.ReportValidationWarnings;
settings.ValidationEventHandler += new ValidationEventHandler(ValidationCallBack);
// Create the XmlReader object.
XmlReader reader = XmlReader.Create("inlineSchema.xml", settings);
// Parse the file.
while (reader.Read()) ;
}
// Display any warnings or errors.
private static void ValidationCallBack(object sender, ValidationEventArgs args)
{
if (args.Severity == XmlSeverityType.Warning)
Console.WriteLine("\tWarning: Matching schema not found. No validation occurred." + args.Message);
else
Console.WriteLine("\tValidation error: " + args.Message);
}
}
Here is a chunk of code I use to validate xml with a local schema:
string errors = string.Empty;
try
{
XmlSchemaSet schemas = new XmlSchemaSet();
schemas.Add(string.Empty, Page.MapPath("~/xml/Schema.xsd"));
XmlDocument doc = new XmlDocument();
doc.Schemas = schemas;
doc.Load(Page.MapPath("~/xml/sampleXML.xml"));
//use this line instead of the one above for a string in memory.
//doc.InnerXml = xmlToValidate;
ValidationEventHandler validator = delegate(object send, ValidationEventArgs ve)
{
errors += "\n" + ve.Severity + ": " + ve.Message;
};
doc.Validate(validator);
}
catch (XmlException xe)
{
errors += "\n" + xe.Message;
}
catch (XmlSchemaValidationException xe)
{
errors += "\n" + xe.Message;
}
I can't quite make out whether you are attempting a generic validate-against-any-referenced-schema, or if you have a specific schema that you validate against every time, and are just not sure how to handle the references.
If it's the latter, then make the schema public on the internet, and tell people to reference it by URI.
If it's the former, then I would suggest the following:
First the user uploads an XML file.
Parse the XML file for a schema reference. Tell them "References to yourSchema.xsd were found; please upload this file below" with a new upload box.
Then, validate the file against the uploaded schema. To do this, modify the Schemas property of your settings object, instead of modifying the ValidationFlags property.