Manipulate json and send it into web request using Powershell - json

Question

I'm trying to manipulate a json object and send it as content into the body of a put / post web request. The source of my json is a file on my disk.
This is my Powershell script:
$urlBase = 'https://mysite.myapp.com/service/api/Item/'
$myJson = (Get-Content 'file.json' | ConvertFrom-JSON)
# Then I manipulate my object
$id = $myJson.id
$myJson.version = '1.2.3.4'
# Request
$response = Invoke-RestMethod -Uri ($urlBase + $id) -Method Put -Body $myJson -ContentType 'application/json' -Headers $hdrs
When I execute my script y get this error message:
Invoke-RestMethod : The remote server returned an error: (400) Bad Request.
At line:18 char:17
+ ... $response = Invoke-RestMethod -Uri ($urlBase + $id) -Method Put -Body ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-RestMethod], WebException
+ FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand
If I change my $myJson asignment for this the request works fine...
$myJson = Get-Content 'file.json'
... , but then I can't manipulate my json before send it.
Edited:
If I try to convert back using ConvertTo-Json I get the same error:
$convertedBack = $myJson | ConvertTo-Json
# Request
$response = Invoke-RestMethod -Uri ($urlBase + $id) -Method Put -Body $convertedBack -ContentType 'application/json' -Headers $hdrs

Answer 1

As pointed out in the comments: you need to convert your object back to JSON using the ConvertTo-Json cmdlet.
I see that you've tried that now and had the same problem. So I ask you this: is the value of $convertedBack exactly what you expected? Dump it to file and check!
The reason I am suspicious of this detail is that ConvertTo-Json has a little gotcha in it. Specifically the -Depth parameter which can cause some data loss.
-Depth
Specifies how many levels of contained objects are included in the JSON representation. The default value is 2.
Example Without -Depth
$basicJsonObject = #"
{
"name": "George",
"properties": {
"mood": "jovial",
"coffee": {
"hasCoffee": true,
"mugContents": {
"milk": false,
"doubleShot": true
}
}
}
}
"#
$psObject = ConvertFrom-Json -InputObject $basicJsonObject
Write-Host "Freshly Imported"
Write-Host "DoubleShot = $($psObject.properties.coffee.mugContents.doubleShot)"
$convertedBack = ConvertTo-Json -InputObject $psObject
$reConverted = ConvertFrom-Json -InputObject $convertedBack
Write-Host "Re-Converted"
Write-Host "DoubleShot = $($reConverted.properties.coffee.mugContents.doubleShot)"
Results
Freshly Imported
DoubleShot = True
Re-Converted
DoubleShot =
Example With -Depth
Change one line of code:
$convertedBack = ConvertTo-Json -InputObject $psObject -Depth 5
Results
Freshly Imported
DoubleShot = True
Re-Converted
DoubleShot = True
Note how the new results include the value from the $reConverted variable. This is because the data is not lost further upstream!