How to read JSON data from Powershell script and iterate through it

Question

I'm starting to learn Powershell and I'm currently trying to read in a JSON file.

Here is my JSON file (named 'versions.json'):

{
    "versions": {
        "1.0.0": {
            "Component1": "1.0.0",
            "Component2": "1.0.0",
            "Component3": "1.0.0",
        },
        "2.0.0": {
            "Component1": "2.0.0",
            "Component2": "2.0.0",
            "Component3": "2.0.0"
        }
    }
}

I would like to read in this JSON file and print out the versions and what they consist of. For example, 1.0.0 consists of Component 1 at 1.0.0, Component 2 at 1.0.0, and Component 3 at 1.0.0.

I'm currently reading in the JSON file with this Powershell line:

$json = (Get-Content "versions.json" -Raw) | ConvertFrom-Json

Now, I want to iterate through $json and print out its data. I'm currently using this:

foreach($v in $json.versions) {
    echo "Data: $v"
}

But, when I run my Powershell script, it prints:

Data: @{1.0.0=; 2.0.0=}

Is this the proper output? I was expecting to at least see two entries for 1.0.0 and 2.0.0. This feels like it may be a syntax issue but I am unsure. I am using Powershell version 5.

It's not a collection, which is why you can't iterate over it. If you do $json.versions | get-member you'll see 1.0.0 and 2.0.0 are the properties of a single item. — Mark Wragg
– Mark Wragg, Commented Aug 7, 2017 at 20:30

Mark Wragg · Accepted Answer · 2017-08-07 20:34:43Z

3

After using ConvertFrom-Json you have a PowerShell object which is a single item that has a versions property which has two sub-properties 1.0.0 and 2.0.0. Your ForEach is attempting to iterate them like a collection, but its just a single object.

However you can iterate over the properties as follows to get the result I think you wanted:

 ($Json.versions.psobject.properties) | foreach-object { "Data: $($_.name)" }

answered Aug 7, 2017 at 20:34

Mark Wragg

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5 Comments

Roka545 Over a year ago

When I run your code snippet, I get "cmdlet ForEach-Object at command pipeline position 1. Supply values for the following parameters: Process[0]"

Mark Wragg Over a year ago

Are you sure you copied it correctly? That suggests you're missing the scriptblock part (this bit { "Data: $($_.name)" })

Roka545 Over a year ago

Hmm, I guess everything has to be on a single line (I moved the "Data:" portion and the brackets down. Now when I run it, I get "Data: " - nothing is there.

Mark Wragg Over a year ago

Just the opening { needs to be on the same line, you can then add line breaks if you want to.

Roka545 Over a year ago

My fault - had a typo in my file. Your snippet works properly. I've accepted your answer.

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