仅将数据写入csv行而不丢失以前的数据？

Question

我有一个带有示例数据的起始 csv，如下所示：

Underlying,AllBlue,AllRed
AUD,1/5/2024,
BRR,,
GBP, 3/10/2024,
CAD,,

今天，2024/04/29，通过另一个过程，生成了一个新的 CSV，例如这样

Underlying,AllBlue,AllRed
AUD,,
BRR,4/29/2024,
GBP,4/29/2024,
CAD,,4/29/2024

并且我希望将仅在“AllBlue”和“AllRed”列中找到的任何“新”数据附加到原始 csv。 期望的结果是

Underlying,AllBlue,AllRed
AUD,1/5/2024,
BRR ,4/29/2024,
GBP,4/29/2024,
CAD,,4/29/2024

注意 2024/04/29 csv 中的新数据如何覆盖原始数据。另外，GBP/AllBlue 单元格如何更新为新日期。

#sandbox testing
$CSVFiles = Get-ChildItem -Path "C:\Sandbox\test" -Filter "*.csv"
 
#put into array
$CSVData = @()

ForEach ($CSVFile in $CSVFiles) {
    $CSVContent = Import-Csv -Path $CSVFile.FullName 
    $CSVData += $CSVContent 
}
 
#output
$CSVData | Export-Csv -Path "C:\Sandbox\testoutput\colors.csv" -NoTypeInformation -Append

这就是我目前正在恢复的内容。

"Underlying","AllBlue","AllRed"
"AUD","1/5/2024",""
"BRR","",""
"GBP","3/10/2024",""
"CAD","",""
"AUD","",""
"BRR","4/29/2024",""
"GBP","4/29/2024",""
"CAD","","4/29/2024"

这会追加数据，但不会覆盖列？。我尝试过多个参数破坏、追加。

Answer 1

# Import-Csv here instead
$sourceCsv = ConvertFrom-Csv @'
Underlying,AllBlue,AllRed
AUD,1/5/2024,
BRR,,
GBP, 3/10/2024,
CAD,,
'@

# Import-Csv here instead
$newCsv = ConvertFrom-Csv @'
Underlying,AllBlue,AllRed
AUD,,
BRR,4/29/2024,
GBP,4/29/2024,
CAD,,4/29/2024
ThisIsALineToAppend,,4/29/2024
'@

# create a hashtable using the Underlying property as keys
$map = $sourceCsv | Group-Object Underlying -AsHashTable

$linesToAppend = foreach ($line in $newCsv) {
    # if the Underlying value of the new Csv exists in the old CSV
    if ($map.ContainsKey($line.Underlying)) {
        # get the object having the same Underlying value of the old CSV
        $value = $map[$line.Underlying][0]
        # if the AllBlue of the new CSV is not null
        if (-not [string]::IsNullOrWhiteSpace($line.AllBlue)) {
            # update the object of the old CSV with this new value
            $value.AllBlue = $line.AllBlue
        }
        # if the AllRed of the new CSV is not null
        if (-not [string]::IsNullOrWhiteSpace($line.AllRed)) {
            # update the object of the old CSV with this new value
            $value.AllRed = $line.AllRed
        }

        # go to the next iteration
        continue
    }

    # else, this Underlying doesn't exist in the old CSV
    # so its gotta be appended
    $line
}

$sourceCsv + $linesToAppend | ConvertTo-Csv