How do I use jq to convert number to string?

Given the following jq command and Json:

jq '.[]|[.string,.number]|join(": ")' <<< '
[
  {
    "number": 3,
    "string": "threee"
  },
  {
    "number": 7,
    "string": "seven"
  }
]
'

I'm trying to format the output as:

three: 3
seven: 7

Unfortunately, my attempt is resulting in the following error:

jq: error: string and number cannot be added

How do I convert the number to string so both can be joined?

Solution 1:

The jq command has the tostring function. It took me a while to learn to use it by trial and error. Here is how to use it:

jq -r '.[] | [ .string, .number|tostring ] | join(": ")' <<< '
[{ "number": 9, "string": "nine"},
 { "number": 4, "string": "four"}]
'
nine: 9
four: 4

Solution 2:

An alternative and arguably more intuitive format is:

jq '.[] | .string + ": " + (.number|tostring)' <<< ...

Worth noting the need for parens around .number|tostring.

Solution 3:

For such simple case string interpolation's implicit casting to string will do it:

.[] | "\( .string ): \( .number )"

See it in action on jq‣play.