Merge two json objects

Question

I have the following inputs - 2 json files one is the base one and the second contains the same properties but the different values, I'd like to merge that objects.

For example:

{
  a:{
    b:"asda"
  }
  c: "asdasd"
}

And the second file:

{
  a:{
   b:"d"
  }
}

And the result should be like this:

{a:{b:"d"},c:"asdasd"}

Is that is possible with powershell?

Answer 1

Join (Join-Object) is not a built-in CmdLet

This is an extension of @Mark's answer which also recurses through child objects.

function merge ($target, $source) {
    $source.psobject.Properties | % {
        if ($_.TypeNameOfValue -eq 'System.Management.Automation.PSCustomObject' -and $target."$($_.Name)" ) {
            merge $target."$($_.Name)" $_.Value
        }
        else {
            $target | Add-Member -MemberType $_.MemberType -Name $_.Name -Value $_.Value -Force
        }
    }
}

merge $Json1 $Json2

$Json1

Answer 2

$Json1 | Join $Json2 -Merge {$Right.$_} | ConvertTo-Json _{(see update below)}

($Json1 ConvertFrom-Json) | Merge ($Json2 ConvertFrom-Json) | ConvertTo-Json

Result:

{
    "c":  "asdasd",
    "a":  {
              "b":  "d"
          }
}

You might consider not to overwrite the left value:

($Json1 ConvertFrom-Json) | Join ($Json2 ConvertFrom-Json) | ConvertTo-Json

In that case the result will be:

{
    "c":  "asdasd",
    "a":  [
              {
                  "b":  "asda"
              },
              {
                  "b":  "d"
              }
          ]
}

For details see: https://stackoverflow.com/a/45483110/1701026

---

Update 2019-11-16
The -Merge parameter has been depleted and divided over the -Discern and -Property parameters (sorry for the breaking change). The good news is that the default parameter settings for an object merge are accommodated in a proxy command named Merge-Object (alias Merge) which simplifies the concerned syntax to just: $Object1 | Merge $Object2. For details, see readme or embedded help.

Answer 3

If you know the names of the elements (per your example above), you could do it explicitly like this:

$Json1 ='{
  a: {
    b:"asda"
  },
  c: "asdasd"
}
' | ConvertFrom-Json

$Json2 = '{
  a:{
   b:"d"
  }
}
' | ConvertFrom-Json


$Json1.a = $Json2.a

Result:

$Json1 | ConvertTo-Json

{
    "a":  {
              "b":  "d"
          },
    "c":  "asdasd"
}

If you're looking for something that will merge the two without knowing the explicit key name, you could do something like the following. This will essentially overwrite any properties in the first Json with those from the second Json, where they are duplicated at the first level (it won't seek matches in the nested properties and again this is an overwrite not a merge):

$Json2.psobject.Properties | ForEach-Object {
    $Json1 | Add-Member -MemberType $_.MemberType -Name $_.Name -Value $_.Value -Force
}