Merging json objects in powershell - json

Question

I have json that looks like this:
{
"Workflow": [
{
"Parameters": {
"Project": "/Path/To/File",
"OtherParam": "True"
}
}
],
"Overrides": [
{
"Special": {
"Parameters": {
"NewParam": "NewStuffGoesHere",
"OtherParam": "False"
}
}
}
]
}
... where I want to use the Overrides.Special section to add or update fields in the workflow object. In other words, given the json above, I want to do something like this:
$config = Get-Content workflow.json | out-string | ConvertFrom-Json
$configWithOverrides = Merge-Object $config.Workflow $config.Overrides.Special
And end up with something like this:
$configWithOverrides
Parameters
----------
#{Project=/Path/To/File; NewParam=NewStuffGoesHere; OtherParam=False}
I can certainly write the Merge-Object function above to add or update values as needed based on what's in the override section, but it seems there should (could?) be a built-in or one-liner way to handle this.
I tried this:
$test = $config.Workflow + $config.Overrides.Special
...but that doesn't quite work.
$test
Parameters
----------
#{Project=/Path/To/File; OtherParam=True}
#{NewParam=NewStuffGoesHere; OtherParam=False}
This enables adding parameters:
>$test.Parameters.NewParam
NewStuffGoesHere
...but it's not so great for updating them
>$test.Parameters.OtherParam
True
False
Note - in this example, I'm choosing to handle the merge after converting the json to a psobject, but that's not a requirement.

Answer 1

I have a one-liner to do what you're asking for. Notice that, as far as I know, PowerShell does not deal directly with json strings. But, once converted to PowerShell objects, it's like any other object.
So, firstly, define your json file, and read it as a single string:
# Requires -Version 4
$jsonFile='c:\temp\jsonfile.json'
$jsonObj=#(gc $jsonFile -raw)|ConvertFrom-Json
Define the property upon which you want to merge the json's objects, and the 1st and 2nd objects:
$property='Parameters'
$1=$jsonObj.Workflow.$property
$2=$jsonObj.Overrides.Special.$property
Now, see the one-liner (which I've splitted in 3, for the sake of clarity):
$MergedJson=[pscustomobject]#{
$property=$2.psobject.properties|%{$11=$1}{$11|add-member $_.name $_.value -ea Ignore}{$11}
}|ConvertTo-Json
You see? $MergedJson holds the following string (using your json string):
{
"Parameters": {
"Project": "/Path/To/File",
"OtherParam": "True",
"NewParam": "NewStuffGoesHere"
}
}
Is that what you're looking for?
P.S.: if you swap the roles of $1 and $2, the common parameters' (like OtherParam) values that prevail, change.