有没有办法使用 PowerShell 从半结构化文本文件创建对象？

Question

我有以下文本文件。我正在尝试从此文件创建 PowerShell 对象。

Item: Car
In Stock: YES
Make: Ford
Model: Taurus
Color: Blue
Miles: 0
Item: Car
Miles: 0
Item: Truck
Item: SUV
Item: Car
In Stock: YES
Make: Honda
Model: Civic
Color: Red
Miles: 0

“Item”属性是每个对象开始的地方。棘手的部分是我需要每个对象都具有相同的属性。如果文本文件中不存在该属性，则获取值“N/A”。我还需要创建一个 'Found:' 属性来插入。

例如，这是我在转换为 PowerShell 对象后尝试获得的输出。

Item: Car
Found: YES
In Stock: YES
Make: Ford
Model: Taurus
Color: Blue
Miles: 0

Item: Car
Found: NO
In Stock: N/A
Make: N/A
Model: N/A
Color: N/A
Miles: 0

Item: Truck
Found: NO
In Stock: N/A
Make: N/A
Model: N/A
Color: N/A
Miles: N/A

Item: SUV
Found: NO
In Stock: N/A
Make: N/A
Model: N/A
Color: N/A
Miles: N/A

Item: Car
Found: YES
In Stock: YES
Make: Honda
Model: Civic
Color: Red
Miles: 0

您可能会想，“这输出太荒谬了。”是的，是的。我只是想用我得到的东西工作。 :)

关于尝试的解决方案..

所以，我一直在尝试做的是插入这些属性和值（如果它们不存在）。

我首先将文件读入一个列表，然后循环遍历该列表。然后，如果该元素与“Item:”匹配，则检查下一个元素。如果它不匹配“里程：”，则开始插入所需的属性。

[System.Collections.Generic.List[System.Object]]$Content = Get-Content file.txt

for ([int]$i = 0; $i -lt $Content.Count; $i++){
    if ($Content[$i] -like "Item:*"){
        if ($Content[$i+1] -like "Miles:*") {
            $Content.Insert($i+1, "Found: NO")
            $Content.Insert($i+2, "In Stock: N/A")
            $Content.Insert($i+3, "Make: N/A")
            $Content.Insert($i+4, "Model: N/A")
            $Content.Insert($i+5, "Color: N/A")
            $Content.Insert($i+6, "Miles: N/A")
        }
    }
}

这种方法似乎可以得到正确的列表结构。虽然，我担心我可能对插入物做出过多的假设。从这里开始，我仍然无法将 PowerShell 对象作为输出。

Answer 1

尝试以下方法（需要 PowerShell (Core) 7+）：

# Define a custom class with the desired properties and default values.
class Custom {
  [string] $Item = ''
  [string] $Found = 'NO'
  [string] ${In Stock}  = 'N/A'
  [string] $Make = 'N/A'
  [string] $Model = 'N/A'
  [string] $Color = 'N/A'
  [int] $Miles = 0
}

# * Split the file into paragraphs that start with an "Item:" line.
# * Convert each paragraph into a hashtable of key-value pairs
#   with ConvertFrom-StringData.
# * Construct an instance of the custom class from each hashtable.
# * Set the value of the .Found property based on which properties
#   were populated.
(Get-Content -Raw file.txt) -split '(?m)(?=^Item:)' -ne '' |
  ConvertFrom-StringData -Delimiter : |
    ForEach-Object {
      $obj = [Custom] $_; if ($obj.Make -ne 'N/A') { $obj.Found = 'YES' }; $obj 
    }

---

在 Windows PowerShell 5.1 中，ConvertFrom-StringData 没有 -Delimiter 参数，因此需要进行额外的工作：^{向Theo 致敬。}

# Define a custom class with the desired properties and default values.
class Custom {
  [string] $Item = ''
  [string] $Found = 'NO'
  [string] ${In Stock}  = 'N/A'
  [string] $Make = 'N/A'
  [string] $Model = 'N/A'
  [string] $Color = 'N/A'
  [int] $Miles = 0
}

# * Split the file into paragraphs that start with an "Item:" line.
# * Convert each paragraph into a hashtable of key-value pairs
#   with ConvertFrom-StringData.
# * Construct an instance of the custom class from each hashtable.
# * Set the value of the .Found property based on which properties
#   were populated.
(Get-Content -Raw file.txt) -split '(?m)(?=^Item:)' -ne '' -replace '(?m)^(.+?):', '$1=' |
  ConvertFrom-StringData |
    ForEach-Object {
      $obj = [Custom] $_; if ($obj.Make -ne 'N/A') { $obj.Found = 'YES' }; $obj 
    }