How to convert a string to an integer in a JSON file using jq?

Question

I use jq to transform a complex json object into a tinier one. My query is:

jq 'to_entries[]| {companyId: (.key), companyTitle: (.value.title), companyCode: (.value.booking_service_code)}' companies.json

Now, the (.key) is parsed as a string, yet I want companyId to be a number.

My result currently looks like this:

{
  "companyId": "1337",
  "companyTitle": "Some company title",
  "companyCode": "oxo"
}

yet it should be like:

{
  "companyId": 1337,
  "companyTitle": "Some company title",
  "companyCode": "oxo"
}

k0pernikus · Accepted Answer · 2019-01-28T11:44:42.013

77

jq has inbuilt functions, you can pipe your key to tonumber:

jq 'to_entries[]| {companyId: (.key)|tonumber, companyTitle: (.value.title), companyCode: (.value.booking_service_code)}' companies.json

As per the docs:

tonumber The tonumber function parses its input as a number. It will convert correctly-formatted strings to their numeric equivalent, leave numbers alone, and give an error on all other input.

Example jq '.[] | tonumber' Input [1, "1"] Output 1 1

edited Jan 28 '19 at 11:44

answered Feb 20 '18 at 14:38

k0pernikus

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Anyway to do this while somehow handling null values? – Canovice Aug 04 '21 at 22:10
@Canovice Please open a new question with that requirement. You can link this answer there. – k0pernikus Aug 23 '21 at 13:17

score 8 · Answer 2 · answered Sep 25 '20 at 14:41

I was trying to turn my string (that converts to a float) to an integer. I was looking for a 'toint' function, one doesn't exist.

jq --arg str "1.435" -n '$str|tonumber'
1.435

I threw a floor in there to make sure the number that was created was an integer:

jq --arg str "1.435" -n '$str|tonumber|floor'
1

This also properly converts the OP original data as well. If you want to guarantee your result is an integer you will need to floor it.

How to convert a string to an integer in a JSON file using jq?

2 Answers2

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