如何使用 Powershell Core 7 解析 HTML table？

Question

我有以下代码：

    $html = New-Object -ComObject "HTMLFile"
    $source = Get-Content -Path $FilePath -Raw
    try
    {
        $html.IHTMLDocument2_write($source) 2> $null
    }
    catch
    {
        $encoded = [Text.Encoding]::Unicode.GetBytes($source)
        $html.write($encoded)
    }
    $t = $html.getElementsByTagName("table") | Where-Object {
        $cells = $_.tBodies[0].rows[0].cells
        $cells[0].innerText -eq "Name" -and
        $cells[1].innerText -eq "Description" -and
        $cells[2].innerText -eq "Default Value" -and
        $cells[3].innerText -eq "Release"
    }

代码在 Windows Powershell 5.1 上工作正常，但在 Powershell Core 7 $_.tBodies[0].rows returns 上无效。

那么，如何访问 PS 7 中 HTML table 的行？

Answer 1

PowerShell [Core]，从 7.2.1 开始，不是否带有内置 HTML 解析器 .

您必须依赖第三方解决方案，例如PowerHTML module that wraps the HTML Agility Pack.

对象模型 的工作方式不同于 Windows PowerShell 中可用的基于 Internet Explorer 的模型；它与标准 System.Xml.XmlDocument type^[1]; see the documentation 和下面的示例代码提供的 XML DOM 相似。

# Install the module on demand
If (-not (Get-Module -ErrorAction Ignore -ListAvailable PowerHTML)) {
  Write-Verbose "Installing PowerHTML module for the current user..."
  Install-Module PowerHTML -ErrorAction Stop
}
Import-Module -ErrorAction Stop PowerHTML

# Create a sample HTML file with a table with 2 columns.
Get-Item $HOME | Select-Object Name, Mode | ConvertTo-Html > sample.html

# Parse the HTML file into an HTML DOM.
$htmlDom = ConvertFrom-Html -Path sample.html

# Find a specific table by its column names, using an XPath
# query to iterate over all tables.
$table = $htmlDom.SelectNodes('//table') | Where-Object {
  $headerRow = $_.Element('tr') # or $tbl.Elements('tr')[0]
  # Filter by column names
  $headerRow.ChildNodes[0].InnerText -eq 'Name' -and 
    $headerRow.ChildNodes[1].InnerText -eq 'Mode'
}

# Print the table's HTML text.
$table.InnerHtml

# Extract the first data row's first column value.
# Note: @(...) is required around .Elements() for indexing to work.
@($table.Elements('tr'))[1].ChildNodes[0].InnerText

^{[1] 特别是关于通过 .SelectSingleNode() 和 .SelectNodes() 方法支持 XPath 查询，通过 .ChildNodes 集合公开子节点，并提供 .InnerHtml / .OuterHtml / .InnerText 属性。代替支持子元素名称的 indexer，提供方法 .Element(<name>) 和 .Elements(<name>)。}

Answer 2

我使用上面的答案作为我的解决方案。我安装了 PowerHTML。我想从 https://www.dicomlibrary.com/dicom/dicom-tags/ 中提取数据表并进行转换。

来自这里：

<tr><td>(0002,0000)</td><td>UL</td><td>File Meta Information Group Length</td><td></td></tr>

为此：

{"00020000", "ULFile Meta Information Group Length"}

$page = Invoke-WebRequest https://www.dicomlibrary.com/dicom/dicom-tags/
$htmldom = ConvertFrom-Html $page
$table = $htmlDom.SelectNodes('//table') | Where-Object {
  $headerRow = $_.Element('tr') # or $tbl.Elements('tr')[0]
  # Filter by column names
  $headerRow.ChildNodes[0].InnerText -eq 'Tag' 
}

foreach ($row in $table.SelectNodes('tr'))
 {$a = $row.SelectSingleNode('td[1]').innerText.Trim()  -replace "`n|`r|\s+", " " -replace "\(",'{"' -replace ",","" -replace "\)",'",'
 $c = $row.SelectSingleNode('td[3]').innerText.Trim() -replace "`n|`r|\s+", " "
 $b=$row.seletSingleNode('td[2]').innerText.Trim() -replace "`n|`r|\s+", ""; $c = '"'+$b+$c+'"},'
 $row = New-Object -TypeName psobject
     $row | Add-Member -MemberType NoteProperty -Name Tag -Value $a
     $row | Add-Member -MemberType NoteProperty -Name Value -Value $c

     [array]$data += $row
}

$data | Out-File c:\scripts\dd.txt

如何使用 Powershell Core 7 解析 HTML table？

How to parse HTML table with Powershell Core 7?

html

powershell

powershell-core