How do I use Json.NET to parse json in PowerShell?

问题

I want to parse JSON in PowerShell but I can't use the new v3 functions that are available in PowerShell. My first thought was to load the JSON.Net assembly and use that to parse the JSON string but it doesn't work as I expect it to.

I have this JSON:

$json = "{""Name"": ""Apple"",  
           ""Price"": 3.99,  
            ""Sizes"": [    
                 ""Small"",    
                 ""Medium"",
                 ""Large""]}"

I load the JSON.NET assembly with this code:

[Reflection.Assembly]::LoadFile("$currentPath\Newtonsoft.Json.dll”)

And tries to parse it with

$result = [Newtonsoft.Json.JsonConvert]::DeserializeObject($json)

Now I expect that $result["Name"] is Apple but I get nothing there. Any ideas?

The code ´$result.ContainsKey("Name")returnsTruebut$result.GetValue("Name")returnsnull`.

回答1:

Ok, so here is how I did it so it works down to at least PowerShell v2 on Windows 2008.

First, load the Json.NET assembly for the version you would like to use, I took the .NET 3.5 version:

[Reflection.Assembly]::LoadFile("Newtonsoft.Json.dll")

I had the JSON in a file since it was used in a deployment configuration I wrote, so I needed to read the file and then parse the json

$json = (Get-Content $FileName | Out-String) # read file
$config = [Newtonsoft.Json.Linq.JObject]::Parse($json) # parse string

Now to get values from the config you need to to use the Item method which seems defined by PowerShell on hashtables/dictionaries. So to get an item that is a simple string you would write:

Write-Host $config.Item("SomeStringKeyInJson").ToString()

If you had an array of things you would need to do something like

$config.Item("SomeKeyToAnArray") | ForEach-Object { Write-Host $_.Item("SomeKeyInArrayItem").ToString() }

To access nested items you write

$config.Item("SomeItem").Item("NestedItem")

That's how I solved parsing JSON with Json.NET in PowerShell.

回答2:

maybe this is what you're after :

http://poshcode.org/2930

    function Convert-JsonToXml {
PARAM([Parameter(ValueFromPipeline=$true)][string[]]$json)
BEGIN { 
   $mStream = New-Object System.IO.MemoryStream 
}
PROCESS {
   $json | Write-Stream -Stream $mStream
}
END {
   $mStream.Position = 0
   try
   {
      $jsonReader = [System.Runtime.Serialization.Json.JsonReaderWriterFactory]::CreateJsonReader($mStream,[System.Xml.XmlDictionaryReaderQuotas]::Max)
      $xml = New-Object Xml.XmlDocument
      $xml.Load($jsonReader)
      $xml
   }
   finally
   {
      $jsonReader.Close()
      $mStream.Dispose()
   }
}
}

function Write-Stream {
PARAM(
   [Parameter(Position=0)]$stream,
   [Parameter(ValueFromPipeline=$true)]$string
)
PROCESS {
  $bytes = $utf8.GetBytes($string)
  $stream.Write( $bytes, 0, $bytes.Length )
}  
}



$json = '{
    "Name": "Apple",
    "Expiry": 1230422400000,
    "Price": 3.99,
    "Sizes": [
        "Small",
        "Medium",
        "Large"
    ]
}'

Add-Type -AssemblyName System.ServiceModel.Web, System.Runtime.Serialization
$utf8 = [System.Text.Encoding]::UTF8                 
(convert-jsonToXml $json).innerXML

Output :

<root type="object"><Name type="string">Apple</Name><Expiry type="number">1230422
400000</Expiry><Price type="number">3.99</Price><Sizes type="array"><item type="s
tring">Small</item><item type="string">Medium</item><item type="string">Large</it
em></Sizes></root>

If you want the name node :

$j=(convert-jsonToXml $json)
$j.SelectNodes("/root/Name")

$j |Select-Xml -XPath "/root/Name" |select -ExpandProperty node

回答3:

If you get here and are using Powershell 5.0, it's available in the powershell gallery

Install-Module Newtonsoft.Json
Import-Module Newtonsoft.Json

$json = '{"test":1}'
[Newtonsoft.Json.Linq.JObject]::Parse($json)

回答4:

Maybe this powershell json parser can help too https://github.com/mori-b/Powershell-Json

来源：https://stackoverflow.com/questions/13968004/how-do-i-use-json-net-to-parse-json-in-powershell

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