how to not skip array containing null using jq? - json

Question

I want to process this data
{
"results": [
{
"headword": "binding",
"senses": [
{
"definition": [
"a promise, agreement etc that must be obeyed"
]
}
]
},
{
"headword": "non-binding",
"senses": [
{
"definition": [
"a non-binding agreement or decision does not have to be obeyed"
],
"examples": [
{
"text": "The industry has signed a non-binding agreement to reduce pollution."
}
]
}
]
}
]
}
into this
{
"headword": "binding",
"definition": "a promise, agreement etc that must be obeyed",
"examples": null
}
{
"headword": "non-binding",
"definition": "a non-binding agreement or decision does not have to be obeyed",
"examples": "The industry has signed a non-binding agreement to reduce pollution."
}
this command
cat data.json | jq '.results[] | {headword: .headword, definition: .senses[].definition[], examples: .senses[].examples[].text}'
errors out with 'Cannot iterate over null'
to overcome that, this command using '.[]?' filter
cat data.json | jq '.results[] | {headword: .headword, definition: .senses[].definition[], examples: .senses[].examples[]?.text}'
but this outputs only
{
"headword": "non-binding",
"definition": "a non-binding agreement or decision does not have to be obeyed",
"examples": "The industry has signed a non-binding agreement to reduce pollution."
}
so, How do you iterate over null and not skip array?

Answer 1

Using an if/else statement may help.
jq '.results[] | {
headword,
definition: .senses[0].definition[0],
examples: (if .senses[0].examples then .senses[0].examples[0].text else null end)
}' data.json

Answer 2

As #oguzismail has implicitly pointed out,
assuming that the senses array has only one element
is risky, especially as the choice of name suggests
it was anticipated that each headword might have more than one sense.
A similar observation could be made about .examples, but
the Q does not make it clear what should be done if .examples has more than one element.
In the following I shall therefore opt for a safe approach,
since it can easily be adjusted to meet more specific requirements.
.results[]
| { headword }
+ (.senses[]
| { definition: .definition[0],
examples: (if has("examples")
then [.examples[].text]
else null end) } )