如何使用 PowerShell 最初将 header 添加到 CSV 文件

Question

我想先将 headers 添加到 CSV 文件。我最初要添加 headers 的原因是对于某些行，某些列值可能为空。

根据 Microsoft 文档，export-csv 仅采用第一行中的 headers/columns。

When you submit multiple objects to Export-CSV, Export-CSV organizes the file >based on the properties of the first object that you submit. If the remaining >objects do not have one of the specified properties, the property value of >that object is null, as represented by two consecutive commas. If the >remaining objects have additional properties, those property values are not >included in the file.

https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/export-csv?view=powershell-6#notes

到目前为止我尝试过的：

$csvContents =@()

foreach ($item in $items) {
$row = New-Object System.Object # Create an object to append to the array
$row | Add-Member -MemberType NoteProperty -Name "header1" -Value "value1"
$row | Add-Member -MemberType NoteProperty -Name "header2" -Value "value2"
$row | Add-Member -MemberType NoteProperty -Name "header3" -Value "value3"
$csvContents += $row # append the new data to the array
}

$csvContents | Export-CSV -NoTypeInformation -Path $ResultCsvPath

问题是例如 Item1 可能只有 header1 和 header3，这意味着这些列是动态的。因此导出后的结果 csv 将仅包含 header1 和 header3，而 header2 将丢失。

我期望的是，我想最初添加 header1、header2、header3。

Answer 1

确保您使用 $null 值的行中的列是否缺少数据。我刚刚对此进行了测试并获得了您期望的输出。

$row = New-Object System.Object # Create an object to append to the array
$row | Add-Member -MemberType NoteProperty -Name "header1" -Value "value1"
$row | Add-Member -MemberType NoteProperty -Name "header2" -Value $null
$row | Add-Member -MemberType NoteProperty -Name "header3" -Value "value3"
$row | Export-Csv -NoTypeInformation test.csv

输出（来自 CSV）

"header1","header2","header3"
"value1",,"value3"

Answer 2

根据你想要的复杂程度，我过去做过类似的事情（我也改变了它以使用 [pscustomobject]）：

$csvcontents = $items | foreach-object {
    If (-not $_.Header1) { $value1 = '' } Else { $value1 = $_.Value1 }
    If (-not $_.Header2) { $value2 = '' } Else { $value1 = $_.Value2 }
    If (-not $_.Header3) { $value3 = '' } Else { $value1 = $_.Value3 }
    [pscustomobject]@{header1 = $_.value1;header2=$value2;$header3=$value3}
}

免责声明，上面没有测试，但它给了你这个想法的要点。

Answer 3

如果 collection 较大，这可能需要一些时间，但以下内容可能对您有用：

假设这是你的 collection

$obj = @(
    [pscustomobject]@{
        'header1' = 'value1'
        'header3' = 'value3'
    },
    [pscustomobject]@{
        'header1' = 'value1'
        'header2' = 'value2'
    },
    [pscustomobject]@{
        'header3' = 'value3'
    },
    [pscustomobject]@{
        'header1' = 'value1'
        'header2' = 'value2'
        'header3' = 'value3'
    }
)

然后您可以添加缺少的属性，例如：

# Try and find all headers by looping over all items.
# You could change this to loop up to a maximum number of items if you like.
# The headers will be captured in the order in which they are found. 
$headers = $obj | ForEach-Object {($_.PSObject.Properties).Name} | Select-Object -Unique

# Find the missing headers in the first item of the collection
# and add those with value $null to it.
$headers | Where-Object { ($obj[0].PSObject.Properties).Name -notcontains $_ } | ForEach-Object {
    $obj[0] | Add-Member -MemberType NoteProperty -Name $_ -Value $null
}

# output on console
$obj

# output to csv file
$obj | Export-Csv -Path 'D:\test.csv' -NoTypeInformation

输出：

header1 header3 header2
------- ------- -------
value1  value3         
value1          value2 
        value3         
value1  value3  value2

Answer 4

请在此处找到基于生成的目录输出创建 CSV 的示例：

$basedir = "E:220205MassUpload1"
$picDir = "$($baseDir)\pics"
$res=ls $picDir
$outputArray = @()
foreach($line in $res) {
    $name = $($line.name).Replace(".png","")
    $outputArray += (
        [pscustomobject]@{
            Title = "$name"
            Brand = 'Brand'
            BulletPoint1='BulletPoint1'
            BulletPoint2='BulletPoint2'
            Description='Description'
            Price='19.95'
            Tags='Tags'
            ImagePath="$($picDir)$($line.name)"

        });
}

$outputArray | Export-csv -NoTypeInformation "$basedir\upload.csv"

它的作用是获取目录中所有元素的列表。

为每个结果创建一个“pscustomobject”并为列创建值，一些是“固定的”，一些是“计算的”。

最后，数组将通过管道传输到 CSV。

如何使用 PowerShell 最初将 header 添加到 CSV 文件

How to add header to a CSV file initially with PowerShell

csv

powershell

export-csv

输出（来自 CSV）