【发布时间】：2015-11-08 01:31:23
【问题描述】：
背景
我希望编写使用Microsoft.VisualBasic.FileIO.TextFieldParser 来解析一些csv 数据的代码。
我为其生成此数据的系统不理解引号；所以我无法逃脱分隔符；而是必须更换它。
我找到了使用上述文本解析器的解决方案，但我只看到人们将它用于文件输入。我宁愿将数据保存在内存中/利用这个类的构造函数，它接受一个流作为输入。
理想情况下，它可以直接从用于管道的任何内存流中获取馈送；但我不知道如何访问它。 在我当前的代码中，我创建了自己的内存流并从管道向它提供数据；然后尝试从中读取。不幸的是，我错过了一些东西。
问题
- 如何在 PowerShell 中读取/写入内存流？
- 是否可以直接从输入函数管道的流中读取？
代码
clear-host
[Reflection.Assembly]::LoadWithPartialName("System.IO") | out-null
#[Reflection.Assembly]::LoadWithPartialName("Microsoft.VisualBasic") | out-null
function Clean-CsvStream {
[CmdletBinding()]
param (
[Parameter(Mandatory = $true, ValueFromPipeline=$true)]
[string]$Line
,
[Parameter(Mandatory = $false)]
[char]$Delimiter = ','
)
begin {
[System.IO.MemoryStream]$memStream = New-Object System.IO.MemoryStream
[System.IO.StreamWriter]$writeStream = New-Object System.IO.StreamWriter($memStream)
[System.IO.StreamReader]$readStream = New-Object System.IO.StreamReader($memStream)
#[Microsoft.VisualBasic.FileIO.TextFieldParser]$Parser = new-object Microsoft.VisualBasic.FileIO.TextFieldParser($memStream)
#$Parser.SetDelimiters($Delimiter)
#$Parser.HasFieldsEnclosedInQuotes = $true
#$writeStream.AutoFlush = $true
}
process {
$writeStream.WriteLine($_)
#$writeStream.Flush() #maybe we need to flush it before the reader will see it?
write-output $readStream.ReadLine()
#("Line: {0:000}" -f $Parser.LineNumber)
#write-output $Parser.ReadFields()
}
end {
#close streams and dispose (dodgy catch all's in case object's disposed before we call Dispose)
#try {$Parser.Close(); $Parser.Dispose()} catch{}
try {$readStream.Close(); $readStream.Dispose()} catch{}
try {$writeStream.Close(); $writeStream.Dispose()} catch{}
try {$memStream.Close(); $memStream.Dispose()} catch{}
}
}
1,2,3,4 | Clean-CsvStream -$Delimiter ';' #nothing like the real data, but I'm not interested in actual CSV cleansing at this point
解决方法
与此同时，我的解决方案只是对对象的属性而不是 CSV 行进行此替换。
$cols = $objectArray | Get-Member | ?{$_.MemberType -eq 'NoteProperty'} | select -ExpandProperty name
$objectArray | %{$csvRow =$_; ($cols | %{($csvRow.$_ -replace "[`n,]",':')}) -join ',' }
更新
我意识到缺少的代码是$memStream.Seek(0, [System.IO.SeekOrigin]::Begin) | out-null;
但是，这并不完全符合预期；即我的 CSV 的第一行显示两次，而其他输出的顺序错误；所以大概我误解了如何使用Seek。
clear-host
[Reflection.Assembly]::LoadWithPartialName("System.IO") | out-null
[Reflection.Assembly]::LoadWithPartialName("Microsoft.VisualBasic") | out-null
function Clean-CsvStream {
[CmdletBinding()]
param (
[Parameter(Mandatory = $true, ValueFromPipeline=$true)]
[string]$CsvRow
,
[Parameter(Mandatory = $false)]
[char]$Delimiter = ','
,
[Parameter(Mandatory = $false)]
[regex]$InvalidCharRegex
,
[Parameter(Mandatory = $false)]
[string]$ReplacementString
)
begin {
[System.IO.MemoryStream]$memStream = New-Object System.IO.MemoryStream
[System.IO.StreamWriter]$writeStream = New-Object System.IO.StreamWriter($memStream)
[Microsoft.VisualBasic.FileIO.TextFieldParser]$Parser = new-object Microsoft.VisualBasic.FileIO.TextFieldParser($memStream)
$Parser.SetDelimiters($Delimiter)
$Parser.HasFieldsEnclosedInQuotes = $true
$writeStream.AutoFlush = $true
}
process {
if ($InvalidCharRegex) {
$writeStream.WriteLine($CsvRow)
#flush here if not auto
$memStream.Seek(0, [System.IO.SeekOrigin]::Begin) | out-null;
write-output (($Parser.ReadFields() | %{$_ -replace $InvalidCharRegex,$ReplacementString }) -join $Delimiter)
} else { #if we're not replacing anything, keep it simple
$CsvRow
}
}
end {
"end {"
try {$Parser.Close(); $Parser.Dispose()} catch{}
try {$writeStream.Close(); $writeStream.Dispose()} catch{}
try {$memStream.Close(); $memStream.Dispose()} catch{}
"} #end"
}
}
$csv = @(
(new-object -TypeName PSCustomObject -Property @{A="this is regular text";B="nothing to see here";C="all should be good"})
,(new-object -TypeName PSCustomObject -Property @{A="this is regular text2";B="what the`nLine break!";C="all should be good2"})
,(new-object -TypeName PSCustomObject -Property @{A="this is regular text3";B="ooh`r`nwindows line break!";C="all should be good3"})
,(new-object -TypeName PSCustomObject -Property @{A="this is regular text4";B="I've got;a semi";C="all should be good4"})
,(new-object -TypeName PSCustomObject -Property @{A="this is regular text5";B="""You're Joking!"" said the Developer`r`n""No honestly; it's all about the secret VB library"" responded the Google search result";C="all should be good5"})
) | convertto-csv -Delimiter ';' -NoTypeInformation
$csv | Clean-CsvStream -Delimiter ';' -InvalidCharRegex "[`r`n;]" -ReplacementString ':'
【问题讨论】：
标签： powershell streamwriter memorystream