jq extract key with - under powershell

Question

I use jq 1.5 in a Windows Environment to modify an json object that i receiving from Amazon s3. I have there a funny Problem. I use jq to extract single keys of the object:

{
  "s3_direct_url": "https://fanzo-photos.s3.amazonaws.com/photos/images/034/005/322/screen1.jpg",
  "url": "https://fanzo-photos.s3.amazonaws.com",
  "fields": {
    "key": "photos/images/034/005/322/screen1.jpg",
    "success_action_status": "200",
    "Content-Type": "image/jpeg",
    "acl": "public-read",
    "policy": "eyJleHBpcmF0aW9uIjoiMjAxOC0xMS0wMlQxMzo0NzoxNVoiLCJjb25kaXRpb25zIjpbeyJidWNrZXQiOiJmYW56by1waG90b3MifSx7ImtleSI6InBob3Rvcy9pbWFnZXMvMDM0LzAwNS8zMjIvc2NyZWVuMS5qcGcifSx7InN1Y2Nlc3NfYWN0aW9uX3N0YXR1cyI6IjIwMCJ9LHsiQ29udGVudC1UeXBlIjoiaW1hZ2UvanBlZyJ9LHsiYWNsIjoicHVibGljLXJlYWQifSx7IngtYW16LWNyZWRlbnRpYWwiOiJBS0lBSlkzWVRCV1NMQzQ2SFdCQS8yMDE4MTEwMi91cy1lYXN0LTEvczMvYXdzNF9yZXF1ZXN0In0seyJ4LWFtei1hbGdvcml0aG0iOiJBV1M0LUhNQUMtU0hBMjU2In0seyJ4LWFtei1kYXRlIjoiMjAxODExMDJUMTI0NzE1WiJ9XX0=",
    "x-amz-credential": "AKIAJY3YTBWSLC46HWBA/20181102/us-east-1/s3/aws4_request",
    "x-amz-algorithm": "AWS4-HMAC-SHA256",
    "x-amz-date": "20181102T124715Z",
    "x-amz-signature": "52d8246536e8743fba8e7668cb65a08a1142221d54a58676b6ab14e3835482a3"
  },
  "id": 34005322,
  "media_type": "InputMedia"
}

If i extract informations from the 'fields' object without a '-' in the key name that works fine. If i try to extract a key with '-' in the name i got following error:

 jq: error: amz/0 is not defined at <top-level>, line 1:
.fields.x-amz-credential          
jq: error: credential/0 is not defined at <top-level>, line 1:
.fields.x-amz-credential              
jq: 2 compile errors
exit status 3

Update: After the hint with the FAQ and the " i rebuild the jq command and tested it in jqplay: .fields."Content-Type" where it works as expected. Under powershell that variant didn't working since the powershell didn't excepting the quotating.

.\jq .fields."Content-Type" jq: error: Type/0 is not defined at <top-level>, line 1: .fields.Content-Type jq: 1 compile error

BR Timo

score 0 · Accepted Answer · answered Nov 02 '18 at 14:00

Any tips?

Yes! If you cannot find the answer in the onine jq manual, check the jq FAQ:

: How can I access the value of a key with hyphens or $ or other special characters in it? Why does .a.["$"] produce a syntax error?

A: The basic form for accessing the value of a key is .["KEYNAME"] where "KEYNAME" is any valid JSON string, but recent versions of jq also allow ."KEYNAME".

Using the basic form might require explicit use of the pipe symbol, as in .["a-b"]|.["x-y"], but this can be abbreviated to .["a-b"]["x-y"].

jq extract key with - under powershell

1 Answers1