Change content of some JSON file using powershell pipeline

Question

I want to change content of JSON file from a bat file. I thought doing that by calling powershell and use a single-line pipeline command.

Here I am so far:

Get-Content test.json -raw | ConvertFrom-Json | Set-ItemProperty -Name "ServiceAccess.Host" -Value "localhost:5000" |  ConvertTo-Json | Set-Content test.json

Here is my JSON file:

{
    "ServiceAccess":  
    {
        "Host":  "localhost:3000"
    }
}

It does not work:

Set-ItemProperty : The input object cannot be bound to any parameters for the command either because the command does not take pipeline input or the input and its properties do not match any of the parameters that take pipeline input. At line:1 char:49 + ... From-Json | Set-ItemProperty -Name "ServiceAccess.Host" -Value "local ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : InvalidArgument: (@{ServiceAccess=}:PSObject) [Set-ItemProperty], ParameterBindingExcept ion + FullyQualifiedErrorId : InputObjectNotBound,Microsoft.PowerShell.Commands.SetItemPropertyCommand

What is the proper way to change a JSON object in the powershell pipeline?

mklement0 · Accepted Answer · 2019-08-02 12:50:32Z

If you must do it all in a single pipeline (spread across multiple lines for readability):

Get-Content test.json -Raw | ConvertFrom-Json |
  ForEach-Object { $_.ServiceAccess.Host = 'localhost:5000'; $_ } |
    ConvertTo-Json | Set-Content test.json

Note that using -Raw to read the entire input file at once makes it possible to write back to the same file in the same pipeline (without -Raw, you'd have to enclose the Get-Content call in (...) to force reading of its lines all at once).

In the ForEach-Object block, the input object is first modified ($_.ServiceAccess.Host = 'localhost:5000'), and then (;) passed through ($_) to ConvertTo-Json for reconversion to JSON, which Set-Content then writes back to the input file.

As for what you tried:

*-Item* cmdlets such as Set-ItemProperty aren't designed for general in-memory object manipulation.

Instead, an item is a specific type of object that a PowerShell provider exposes, such as a file or folder in the case of the filesystem provider, or a registry key in the case of the registry provider.

Bacon Bits · Accepted Answer · 2019-08-01 15:07:21Z

$Json = Get-Content test.json -Raw | ConvertFrom-Json
$Json.ServiceAccess.Host = 'localhost:5000'
$Json | ConvertTo-Json | Set-Content test.json

If you bang on it for awhile you could probably get this into a single line of code, but you may run into file locking issues when Get-Content and Set-Content are operating on the same file in the same pipeline.

Be aware that PowerShell's JSON support is a little quirky. This is partially due to the fact that it uses the .Net dialect of JSON, which isn't always identical to the JSON that other systems use. Second, JSON support is a relatively recent addition, so Windows PowerShell (v5.1 and below) is more quirky than PowerShell Core (v6+). If your outermost JSON element is an unnamed array, for example, PowerShell will tend to drop the square brackets.

Krzysztof Cieślak · Accepted Answer · 2019-08-01 15:07:31Z

0

try this:

$json = get-content test.json | ConvertFrom-Json           
$json | % { $_.ServiceAccess.Host = "localhost:5000" }     
$json | ConvertTo-Json | out-file test1.json

answered Aug 1, 2019 at 15:07

Krzysztof Cieślak

222 bronze badges

Collectives™ on Stack Overflow

Change content of some JSON file using powershell pipeline

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related