How to parse a JSON file to variables with the windows command line?

Question

I have this JSON file called test.json which says:

{
    "test":true,
    "limit": 
    {
        "min":0.5,
        "max":1.5
    }
}

I'd like to be able to read this file in the Windows command line and have these objects parsed as variables.

How would I do this?

@Manish - Could you give me an example? – Kriem Oct 14 '13 at 08:34 — Kriem, Oct 14 '13 at 08:34

score 11 · Accepted Answer · edited May 23 '17 at 12:00

11

If you use Windows Powershell as your command line, you can use the ConvertFrom-JSON cmdlet: http://powershelljson.codeplex.com/

Make sure your PowerShell version is above 3.0, as ConvertFrom-JSON is available from that version.

If you use plain old CMD, you'll need an external tool for it. I like jq: http://stedolan.github.io/jq/. The tutorial uses curl for the examples, but you can just as easily use echo or read the JSON from a file.

edited May 23 '17 at 12:00

Community

1
1

answered Oct 14 '13 at 08:36

Idan Arye

12,402
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I'm afraid I can't use Powershell. – Kriem Oct 14 '13 at 08:43
1

See the second part of my answer – Idan Arye Oct 14 '13 at 08:47
I'm not sure how this would help me create variables. Am I missing something? – Kriem Oct 14 '13 at 09:03
CMD variables are strings - the only way for them to hold complex hierarchical structures is if those structures are serialized. So, whenever you need a specific value from the JSON, you stream the variable through `jq` with a selector to select what you need. – Idan Arye Oct 14 '13 at 09:34
1

We have the exact same reputations core btw :P – Kriem Oct 14 '13 at 10:43
Quick question: how would I set a variable to the output of this? Say, I have limit.min, which outputs 0.5. How would I set it to a variable? – Kriem Oct 15 '13 at 07:37
6

To answer my own question: `FOR /F "delims=" %%i in ('type test.json ^| jq .limit.min') DO SET min=%%i` – Kriem Oct 15 '13 at 07:50
4

Note that you don't need to use `type` here - you can use the file redirection operator `<`, and write `'jq .limit.min ^< test.json'`. – Idan Arye Oct 15 '13 at 07:54

score 1 · Answer 2 · answered May 14 '20 at 17:04

1

PowerShell example. Create from file: $js = Get-Content file.json | ConvertFrom-Json. Get subkey: $js.key.subkey

answered May 14 '20 at 17:04

Григорий

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This should be the very best answer. Works for me, without installing anything. – Yuanqiu Li Sep 01 '22 at 09:56

score 0 · Answer 3 · answered Jun 06 '20 at 15:18

I'd like to be able to read this file in the Windows command line and have these objects parsed as variables.

I'll interpret this as, you want to do:

SET min=0.5
SET max=1.5

I'd recommend the powerful tool xidel for this task.

Basic command:

xidel -s test.json -e "$json/limit/min" -e "$json/limit/max"
xidel -s test.json -e "$json/limit/(min,max)"

Whether you use 2 queries to return each value, or 1 query to return both values, both commands should return:

0.5
1.5

Export with custom variable-names:

FOR /F "delims=" %A IN ('xidel -s test.json -e "min:=$json/limit/min" -e "max:=$json/limit/max" --output-format^=cmd') DO %A
FOR /F "delims=" %A IN ('xidel -s test.json -e "$json/limit/(min:=min,max:=max)" --output-format^=cmd') DO %A

Both commands do:

SET min=0.5
SET max=1.5

Export with key-names as variable-names:

FOR /F "delims=" %A IN ('xidel -s test.json -e "$json/(limit)() ! eval(x'{.}:=$json/limit/{.}')[0]" --output-format^=cmd') DO %A

To answer my own question: FOR /F "delims=" %%i in ('type test.json ^| jq .limit.min') DO SET min=%%i

If that's all you want, then...

FOR /F "delims=" %A IN ('xidel -s test.json -e "$json/limit/min"') DO SET min=%A

or...

FOR /F "delims=" %A IN ('xidel -s test.json -e "min:=$json/limit/min" --output-format^=cmd') DO %A

...is all you need.

How to parse a JSON file to variables with the windows command line?

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