I have a CSV file in my project resources which I want to read using FileIO.TextFieldParser
I tried Dim parser = new TextFieldParser(My.Resources.ArticlesCSV), but since TextFieldParser expects either a path (as string) or a stream, this is not working.
I guess one possibility is to convert the resource to a stream, but I cannot find how to do that...
What is the best way to get this working?
You can create a new instance of IO.StringReader which is of type TextReader that TextFieldParser will accept. Just pass your CSV file (Thanks to AndrewMorton)
Using strReader As New IO.StringReader(My.Resources.ArticlesCSV)
Using textparser As New TextFieldParser(strReader)
textparser.Delimiters = {","}
While Not textparser.EndOfData
Dim curRow = textparser.ReadFields()
' Do stuff
End While
End Using
End Using
Related
I'm using PDF Extractor (from here) to get the text from PDF attachments in emails.
It seems to me that the only way I can extract the text is to save the PDF to a file, and then using the code.
Private Function ReadPdfToStringList(tempfilename As String) As List(Of String)
Dim extractedText As String
Using pdfFile As FileStream = File.OpenRead(tempfilename)
Using extractor As Extractor = New Extractor()
extractedText = extractor.ExtractToString(pdfFile)
End Using
End Using
DeleteTempFile()
Return New List(Of String)(extractedText.Split(Chr(13)))
End Function
to extract a list of Strings from the PDF file.
However, I cant seem to extract text from the attachment directly. The 'extractor' doesnt seem to be able to handle any source other than a file on disk.
Is there any possible way of either tricking the 'extractor' into opening a file from memory maybe by creating an in memory file stream?
I've tried using a MemoryStream like this:
Private Function ReadPdfMemStrmToStringList(memstream As MemoryStream) As List(Of String)
Dim extractedText As String
Using extractor As Extractor = New Extractor()
extractedText = extractor.ExtractToString(memstream)
End Using
Return New List(Of String)(extractedText.Split(Chr(13)))
End Function
but because the extractor is assuming the source is a disk file, it returns an error saying that it cant find a temporary file.
To be honest I've spent quite a bit of time trying to understand memory streams and they don't seem to fit the bill.
UPDATE
Here also is the code that I'm using to save the attachment to the MemoryStream.
Private Sub SaveAttachmentToMemStrm(msg As MimeMessage)
Dim memstrm As New MemoryStream
For Each attachment As MimePart In msg.Attachments
If attachment.FileName.Contains("booking") Then
attachment.WriteTo(memstrm)
End If
Next
'this line only adds the memory stream to a List (of MemoryStream)
attachments.Add(memstrm)
End Sub
Many apologies if I've missed something obvious.
I'm creating a file on the fly on a WebAPI call, and sending that file back to the client.
I think I'm misunderstanding flush/close on a FileStream:
Dim path As String = tempFolder & "\" & fileName
Dim result As New HttpResponseMessage(HttpStatusCode.OK)
Dim stream As New FileStream(path, FileMode.Open)
With result
.Content = New StreamContent(stream)
.Content.Headers.ContentDisposition = New Headers.ContentDispositionHeaderValue("attachment")
.Content.Headers.ContentDisposition.FileName = fileName
.Content.Headers.ContentType = New Headers.MediaTypeHeaderValue("application/octet-stream")
.Content.Headers.ContentLength = stream.Length
End With
'stream.Flush()
'stream.Close()
'Directory.Delete(tempFolder, True)
Return result
You can see where I've commented things out above.
Questions:
Does the stream flush/close itself?
How can I delete the tempFolder after returning the result?
On top of all this, it would be great to know how to generate the file and send it to the user without writing it to the file system first. I'm confident this is possible, but I'm not sure how. I'd love to be able to understand how to do this, and solve my current problem.
Update:
I went ahead with accepted answer, and found it to be quite simple:
Dim ReturnStream As MemoryStream = New MemoryStream()
Dim WriteStream As StreamWriter = New StreamWriter(ReturnStream)
With WriteStream
.WriteLine("...")
End With
WriteStream.Flush()
WriteStream.Close()
Dim byteArray As Byte() = ReturnStream.ToArray()
ReturnStream.Flush()
ReturnStream.Close()
Then I was able to stream the content as bytearraycontent:
With result
.Content = New ByteArrayContent(byteArray)
...
End With
On top of all this, it would be great to know how to generate the file and send it to the user without writing it to the file system first. I'm confident this is possible, but I'm not sure how. I'd love to be able to understand how to do this, and solve my current problem.
To do the same thing without writing a file to disk, you might look into the MemoryStream class. As you'd guess, it streams data from memory like the FileStream does from a file. The two main steps would be:
Take your object in memory and instead of writing it to a file, you'd serialize it into a MemoryStream using a BinaryFormatter or other method (see that topic on another StackOverflow Q here: How to convert an object to a byte array in C#).
Pass the MemoryStream to the StreamContent method, exactly the same way you're passing the FileStream now.
I need download a CSV file and then read it. Here is my code:
tickerValue = "goog"
Dim strURL As String = "http://ichart.yahoo.com/table.csv?s=" & tickerValue
Dim strBuffer As String = RequestWebData(strURL)
Using streamReader = New StreamReader(strBuffer)
Using reader = New CsvReader(streamReader)
I keep getting this error: An unhandled exception of type 'System.ArgumentException' occurred in mscorlib.dll Additional information: Illegal characters in path.
What am I doing wrong?
Additional Info
In another part of my program I use this code and it works fine.
Address = http://www.nasdaq.com/screening/companies-by-industry.aspx?exchange=AMEX&render=download
Dim strBuffer As String = Historical_Stock_Prices.RequestWebData(Address)
Using streamReader = New StringReader(strBuffer)
Using reader = New CsvReader(streamReader)
Isn't my second code the same concept as my problem code?
you are giving it, essentially, a web url. somewhere in your code, it does not support the web url. it could be the streamreader. it could be the CsvReader.
what line of code does this point to?
the best bet is to save the file TO DISK, then read from disk.
UPDATE
here is an example to SAVE to disk:
using writer as new StreamWriter("C:\Test.csv")
writer.Write(strBuffer)
writer.Close()
end using
here is an example to READ from disk:
using strReader as new StreamReader("C:\Test.csv")
' this code is presumably how it works for reading into the CsvReader:
using reader as new CsvReader(strReader)
' now do your thing
end using
strReader.Close()
end using
I've nicked some code from msdn to write and read to an xml file to persist my data, but I need a little help with it. I have a dynamic array called darr. As I understand it, I use this code to store it in an xml file:
Dim objStreamWriter As New StreamWriter("C:\temp\test.xml")
Dim x As New XmlSerializer(darr.GetType)
x.Serialize(objStreamWriter, darr)
objStreamWriter.Close()
And this to read it:
Dim objStreamReader As New StreamReader("C:\temp\test.xml")
darr = x.Deserialize(objStreamReader)
objStreamReader.Close()
The thing is, I want the app to read from the file on startup, which means the second block gets called first and if the file doesn't exit yet, it throws an exception. (The first block automatically creates the file if not found.) So two questions:
Is there a way to have the app create the file automatically the first time it runs?
Since the file will be empty... will the code work? If not, is there a workaround? (Okay that's three questions!)
If Not File.Exists("C:\temp\test.xml") Then
' Create the file.
Dim file As System.IO.FileStream
file = System.IO.File.Create("C:\temp\test.xml")
Else
Dim objStreamWriter As New StreamWriter("C:\temp\test.xml")
Dim x As New XmlSerializer(darr.GetType)
x.Serialize(objStreamWriter, darr)
objStreamWriter.Close()
End If
I am making a class that is to help with saving some strings to a local text file (I want to append them to that file and not overwrite so that it is a log file). When I write with the streamwriter to find the end of the previous text, I get an error "the file is not available as it is being used by another process". I looked into this problem on MSDN and I got very little help. I tried to eliminate some variables so I removed the streamreader to check was that the problem and it was. When I tried to write to the file then it worked and I got no error so this made me come to the conclusion that the problem arose in the streamreader. But I could not figure out why?
Here is the code:
Public Sub SaveFile(ByVal Task As String, ByVal Difficulty As Integer, ByVal Time_Taken As String)
Dim SW As String = "C:/Program Files/Business Elements/Dashboard System Files/UserWorkEthic.txt"
Dim i As Integer
Dim aryText(3) As String
aryText(0) = Task
aryText(1) = Difficulty
aryText(2) = Time_Taken
Dim objWriter As System.IO.StreamWriter = New System.IO.StreamWriter(SW, True)
Dim reader As System.IO.StreamReader = New System.IO.StreamReader(SW, True)
reader.ReadToEnd()
reader.EndOfStream.ToString()
For i = 0 To 3
objWriter.WriteLine(aryText(reader.EndOfStream + i))
Next
reader.Close()
objWriter.Close()
End Sub
As Joel has commented on the previous answer it is possible to change the type of locking.
Otherwise building on what Neil has suggested, if to try to write to a file with a new reader it is difficult not to lose the information already within the file.
I would suggest you rename the original file to a temporary name, "UserWorkEthicTEMP.txt" for example. Create a new text file with the original name. Now; read a line, write a line, between the two files, before adding your new data onto the end. Finally Delete the temporary file and you will have the new file with the new details. If you have an error the temporary file will serve as a backup of the original. Some sample code below:
Change file names
Dim Line as string
line=Reader.readline
Do until Line=nothing
objwriter.writeline(line)
line=reader.readline
loop
add new values on the end and remove old file
You are trying to read and write to the same file and this is causing a lock contention. Either store the contents of the file into a variable and then write it back out including your new data to the file.
Psuedo
Reader.Open file
String content = Reader.ReadToEnd()
Reader.Close
Writer.Open file
Loop
Writer.Write newContent
Writer.Close