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selecting dates greater than from xml using C#

I am getting myself confused in Powershell in trying to use C# to fill a spreadsheet with two columns. The first is "start" and is what I need help with most. I want this to populate with dates greater than 31st July of a given year as entered as a string at the start. The below is part of what i'm using, and the whole thing is giving me a spreadsheet, but just not the dates I need. It's the line that starts $dr = $DS.Tables which I have been tampering with but to no avail.
$fileyear = "2017";
###Location of default DLLs
$DllsDir = [System.IO.Path]::Combine($PSScriptRoot,"dlls")
Write-Output "Dll Path "+$DllsDir
###Load default DLLs
foreach ($dll in [System.IO.Directory]::GetFiles($DllsDir,"*.dll",
[System.IO.SearchOption]::AllDirectories))
{
[reflection.assembly]::loadfrom($dll);
}
Write-Output "Dlls loaded";
###declare objects
$DS = New-Object System.Data.DataSet;
$DS.ReadXml($DBPath,[System.Data.XmlReadMode]::Auto);
$dt = New-Object System.Data.DataTable;
$dt.Columns.Add("Start");
$dt.Columns.Add("ULIN");
$dr = $DS.Tables["LearningDelivery"].Select("LearnStartDate >
(31/07/"+$fileyear+")");
[datetime]$LearnStartDate = $dr["LearnStartDate"]
Write-Output $dt.Rows.Count;

I guess that the date is not in the correct format. The format depends on the region your machine is configured.
I would build the date using the ISO format. Check for example this question for a reference: DataTable.Select date format problem

Inconsistent DateTime conversion behaviour in .NET Web Service

Problem
I've a Windows app syncs with the Server using SharePoint hosted Web Services.
When the app syncs to the server using LAN (goes through an internal Proxy server) all the DateTime formats are in dd/MM/yyyy format (which is how it is intended to be)
However, when the app syncs over 4G,all DateTime formats are in MM/dd/yyyy format.
This happens for all data inbound and outbound.
Server
Windows Server 2012 with SharePoint 2013 hosting SOAP services
Region: Singapore
Format: English (Singapore)
Client
Windows 10 tablet app
Region: Singapore
Format: English (Singapore)
Other information:
1. It is the same tablet being used on both WiFi and 4G, so we can rule
out 2 tablets having different regional settings.
2. I've verified that the Windows 10 app passes the formats correctly and it is the server that behaves differently over WiFi and 4G.
3. I beleive that the issue is caused by .NET itself and not because of SharePoint. However, I don't want to rule it out as I'm not sure of the actual cause. Please comment if you require any further information if you feel that it is caused because of SharePoint
Snippets:
I've skipped the using statements and SPWeb statements in the snippet to keep it simple. And the LastModifiedTime field in the SPList of type DateTime and not single line text.
Model
public class Record
{
public string ID {get; set}
public string ModifiedDateTime {get; set;} //Don't ask why it is not a DateTime object. It was too late by the time I took over
}
Web Service
public class WebService : IWebService
{
public List<Record> GetUpdates(string lastModifiedTime)
{
SPQuery query= QueryBuilder.GetUpdateQuery(lastModifiedDateTime);
SPList spRecordList = spWeb.Lists["Record"];
SPListItemCollection results = spRecordList.GetItems(query);
List<Record> records = new List<Record>();
foreach(SPListItem spRecord in results)
{
Record record = new Record();
record.ID = spRecord.ID.ToString();
record.ModifiedDateTime = Convert.ToString(spRecord["LastModifiedTime"]);
//1 June 2015 would return as 01/06/2015 in WiFi but 06/01/2015 on 4G
records.Add(record);
}
return records;
}
public Record CreateOrUpdateRecord(Record record)
{
SPListItem spRecord = null;
SPList spRecordList = spWeb.Lists["Record"];
if(string.IsNullOrEmpty(record.ID))
{
spRecord = spRecordList.AddItem();
record.ID = spRecord.ID.ToString();
}
else
{
spRecord = spRecordList.GetItemByID(record.ID);
}
DateTime modified = Convert.ToDateTime(record.Modified);
spRecord["LastModifiedTime"] = modified;
/*
Say ModifiedDateTime is 1 June 2015.
Then on WiFi, modified = 01/06/2015
On 4G, modified = 06/01/2015
*/
return record;
}
}
Now, I've fixed the problem by using format strings when converting between string and DateTime and vice-versa. So more or less, I've got it working for now.
So my question here is, what is the reason behind this behaviour? If possible, please cite links to documentation or references to any other sources that explain this behaviour
Is it possible that the server infers the culture info from the request header? I've always thought that the DateTime.Parse()/Convert.ToDateTime() always got the defaults from the regional settings of the machine it runs on.

First of all, a DateTime does not have any implicit format. It just have date and time values. Format concept only applies when you get it textual (string) representation. I strongly suggest to change this data type from string to DateTime if you can that returns by web service.
I've verified that the Windows 10 app passes the formats correctly and
it is the server that behaves differently over WiFi and 4G
There is no such a thing. Parsing string to DateTime or vice versa does not depends on how you connected to internet. It is all about culture settings.
Since you use it as;
DateTime modified = Convert.ToDateTime(record.Modified);
This code will use CurrentCulture settings by default where it's located. Since you said;
It is the same tablet being used on both WiFi and 4G, so we can rule
out 2 tablets having different regional settings
One regional settings parse your string as a 6 January and the other settings parse your string as 1 June. That's too normal. Looks like one setting uses dd/MM/yyyy format and the other one uses MM/dd/yyyy.
As a solution, you can use DateTime.ParseExact method to specify exact culture that matches with your string. Or you can equalize regional settings on both tablet.
For example;
DateTime dt = DateTime.ParseExact("01/06/2015", "dd/MM/yyyy", CultureInfo.InvariantCulture);
will parse as 1 June 2015 but
DateTime dt = DateTime.ParseExact("01/06/2015", "MM/dd/yyyy", CultureInfo.InvariantCulture);
will parse as 6 January 2015.

File creation time in C#

I need to get when a file was created - I have tried using:
FileInfo fi = new FileInfo(FilePath);
var creationTime = fi.CreationTimeUtc;
and
var creationTime = File.GetCreationTimeUtc(FilePath);
Both methods generally return the wrong creation time - I guess it is being cached somewhere.
The file is deleted and re-created with the same name and I need to know when/if it has been re-created (by checking if the created date/time has changed) - I had planned to do this by seeing it the file creation time had changed but I have found this to be inaccurate.
I'm working on Win 7 and if I check File Explorer it shows the new file creation time correctly.
I have also tried using the FileSystemWatcher but it doesn't entirely work for my use case. E.g. if my program is not running, the FileSystemWatcher is not running, so when my program starts up again I don't know if the file has been deleted and recreated or not.
I've seen MSDN http://msdn.microsoft.com/en-us/library/system.io.file.getcreationtime.aspx where it says:
This method may return an inaccurate value, because it uses native functions whose values may not be continuously updated by the operating system.
But I have also tried using their alternative suggestion and setting the SetCreationDate after creating a new file but I also find that this doesn't work. See test below:
[Test]
public void FileDateTimeCreatedTest()
{
var binPath = System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase);
var fullFilePath = Path.Combine(binPath, "Resources", "FileCreatedDatetimeTest.txt");
var fullFilePathUri = new Uri(fullFilePath);
var dateFormatted = "2013-08-17T15:31:29.0000000Z"; // this is a UTC string
DateTime expectedResult = DateTime.MinValue;
if (DateTime.TryParseExact(dateFormatted, "o", CultureInfo.InvariantCulture,
DateTimeStyles.AssumeUniversal, out expectedResult)) // we expect the saved datetime to be in UTC.
{
}
File.Create(fullFilePathUri.LocalPath);
Thread.Sleep(1000); // give the file creation a chance to release any lock
File.SetCreationTimeUtc(fullFilePathUri.LocalPath, expectedResult); // physically check what time this puts on the file. It should get the local time 16:31:29 local
Thread.Sleep(2000);
var actualUtcTimeFromFile = File.GetCreationTimeUtc(fullFilePathUri.LocalPath);
Assert.AreEqual(expectedResult.ToUniversalTime(), actualUtcTimeFromFile.ToUniversalTime());
// clean up
if (File.Exists(fullFilePathUri.LocalPath))
File.Delete(fullFilePathUri.LocalPath);
}
Any help much appreciated.

You need to use Refresh:
FileSystemInfo.Refresh takes a snapshot of the file from the current
file system. Refresh cannot correct the underlying file system even if
the file system returns incorrect or outdated information. This can
happen on platforms such as Windows 98.
Calls must be made to Refresh before attempting to get the attribute
information, or the information will be outdated.
The key bits from MSDN indicate that it takes a snapshot and attribute information..will be outdated.

Try using FileInfo and Refresh method of it
fileInfo.Refresh();
var created = fileInfo.CreationTime;
this should work

File.Create(fullFilePathUri.LocalPath);
Thread.Sleep(1000); // give the file creation a chance to release any lock
That is not how you do it. File.Create creates stream writer which should be closed to release the lock without any waiting. If you find yourself using Thread.Sleep, you will often find that you are doing something wrong.

If the file described in the path parameter does not exist, this method returns 12:00 midnight, January 1, 1601 A.D. (C.E.) Coordinated Universal Time (UTC), adjusted to local time.
https://learn.microsoft.com/en-us/dotnet/api/system.io.file.getcreationtime?view=netframework-4.8

GetLastWriteTime returning 12/31/1600 7:00:00 PM

I am using the following code to write the Date Modified time of a Directory to a label
string selectedPath = comboBox1.SelectedItem.ToString();
DateTime lastdate = Directory.GetLastWriteTime(selectedPath);
datemodified.Text = lastdate.ToString();
It returns the date 12/31/1600 7:00:00 PM which I have no clue where it is getting that date from. Can anyone help me understand why it is returning that date and how I can fix it? I'm using .NET 3.5

From the documentation:
If the directory described in the path parameter does not exist, this method returns 12:00 midnight, January 1, 1601 A.D. (C.E.) Coordinated Universal Time (UTC), adjusted to local time.
So presumably your time zone is UTC-5 (in January), and the directory doesn't exist...

first thought is that of is your time set correctly. Second thought is to right click on that folder and see what it says in properties. Lastly I'd make new test folder and run that bit of GetLastWriteTime tests on it so you know what you are getting back.

GetLastWriteTime not always return reliable date time, use this
string selectedPath = comboBox1.SelectedItem.ToString();
DateTime now = DateTime.Now;
TimeSpan localOffset = now - now.ToUniversalTime();
DateTime lastdate = File.GetLastWriteTimeUtc(selectedPath) + localOffset;
datemodified.Text = lastdate.ToString();

Old question, but today I faced this issue. That particular date is also returned when your path is invalid or the file doesn't exists, because there is no built in exception in any of those cases.

An easy way to test for file not found with the result of GetLastWriteTime()/GetLastWriteTimeUtc() without hardcoding the sentinel epoch date/times that are used to indicate a file/dir not found condition, is as follows:
// ##### Local file time version #####
DateTime fileTimeEpochLocal=DateTime.FromFileTime(0);
// Use File.GetLastWriteTime(pathname) for files
// and Directory.GetLastWriteTime(pathname) for directories
DateTime lastWriteTime=Directory.GetLastWriteTime(selectedPath);
// Check for a valid last write time
if (lastWriteTime!=fileTimeEpochLocal) // File found
DoSomethingWith(selectedPath,lastWriteTime);
else // File not found
HandleFileNotFound(selectedPath);
// ##### UTC file time version #####
DateTime fileTimeEpochUtc=DateTime.FromFileTimeUtc(0);
// Use File.GetLastWriteTimeUtc(pathname) for files
// and Directory.GetLastWriteTimeUtc(pathname) for directories
DateTime lastWriteTimeUtc=Directory.GetLastWriteTimeUtc(selectedPath);
// Check for a valid last write time
if (lastWriteTimeUtc!=fileTimeEpochUtc) // File found
DoSomethingWith(selectedPath,lastWriteTimeUtc);
else // File not found
HandleFileNotFound(selectedPath);

In .net core, you will need to get the absolute path of the file.
Add reference to Microsoft.Extensions.Hosting and inject that into your constructor.
The ContentRootPath property will be your web root.
Grab your server path
var Files = FIO.Directory.GetFiles("Unzipped");
This will be your actual path
var Path = string.Format(#"{0}\{1}",WebRootPath, Files[0]);
var CreationDate = File.GetLastWriteTime(Path);

C# P/Invoke Attribute

New to C# Compact edition 6.5. I am trying to set the datetime on a file which seems to be off by 5 hours from the actual system time. I am doing only this to create the file:
FileStream fs= File.Create(name);
Just doing this the Created date is 5 hours ahead...if I try and set the CreationTime I get a compile error saying the Attribute is Readonly, seriously?
FileInfo fi = new FileInfo(name);
fi.CreationTime = date;
So my question is since I am new to C# how do you get access to a "readonly" Attribute in the CE framework? I see mentioning of P/Invoke but seems to work on methods only and not attributes. Anyone can given a quick demo on how to do this?
I've tried this solution and still get the file writing UTC even though I send it the current local time

I just ran this:
[MTAThread]
static void Main()
{
var name = "\\foo.txt";
var info = new FileInfo(name);
using (info.Create()) { }
info.Refresh();
var createTime = info.CreationTime;
var now = DateTime.Now;
var delta = now - createTime;
Debug.WriteLine(delta.ToString());
}
And got this output:
00:00:00.0140000
Which seems to be correct to me.

You can't modify the CreationTime of a file. It's set once and only once when the file is created. If you're willing to use P/Invoke to set the time, you can check out this similar question - c# - Change file LastWriteDate in Compact Framework
Instead of hacking the problem, though, you should fix the root cause. If there's an issue with the creation time of the file, I would consider checking your system's time settings (including timezone).