I have two JSON files and want to transfer collection of objects from one file to another. Suppose, the from.json file contains property which represents collection of clients:

"Clients": 
[
  {
    "Name": "Name1",
    "Age": "12"
  },
  {
    "Name": "Name2",
    "Age": "14"
  }
]

to.json file contains an empty collection, "Objects: []" ,which must be filled with objects from from.json. Each objects in toJson variable must contain additional property - Id, so eventually, my "to.json" file should look like this:

"Objects":
[
  {
    "Id": "{new-id}",
    "Name": "Name1",
    "Age": "12"
  },
  {
    "Id": "{new-id}",
    "Name": "Name1",
    "Age": "12"
  }
]

I've converted two files into variables:

$fromJson = (Get-Content -Raw -Path {fromPath}) | ConvertFrom-Json
$toJson = (Get-Content -Raw -Path {toPath}) | ConvertFrom-Json

I know that objects from fromJson to toJson can be transferred in the following manner: toJson.Objects = fromJson.Clients, but that's not enough in my case. I think that it could be done by iterating through fromJson.Clients array but have no idea how to create an object and add it into toJson.Objects collection.

CodePudding user response：

Here's a more efficient solution, based on:

• Use of a calculated property with Select-Object, which allows you to place the new property first in the output objects.

• Instead of building the array one by one with = (which is inefficient, because a new array must technically be created behind the scenes in every iteration), the solution below lets PowerShell collect the output objects of the Select-Object call in an array automatically (the [array] type constraint is needed to ensure that an array is created even if only one object happens to be output.)

# Sample input.
$fromJson = ConvertFrom-Json '{"Clients":[{"Name":"Name1","Age":"12"},{"Name":"Name2","Age":"14"}]}'
$toJson = ConvertFrom-Json '{ "Objects": [] }'

[array] $toJson.Objects = 
          $fromJson.Clients |
            Select-Object @{ Name='Id'; Expression = { [string] (New-Guid) } }, * 
 
$toJson | ConvertTo-Json -Depth 3 # append | Set-Content as needed.

CodePudding user response：

Kind of new to the PowerShell, but after a bit of investigation came up with the following solution:

fromJson.Clients | ForEach-Object {
  $_ | Add-Member -MemberType NoteProperty -Name 'Id' -Value ([guid]::NewGuid().Guid.ToString())
  $toJson  = $_
}
...
$toJson | ConvertTo-Json | Out-File {to.json_path}

Frankly, don't know if that is a 'proper' way to do that, but generally it works for that particular case. For now, see no other solution.