Parsing stops on null or [] - parsing

Question

I have this filter working well but after a new use case where the property "p" can be null or a empty array [], the parser stop to evaluate the expression.
".p[]?.product.productId" the issue is here, when p is null or an empty array [].
When I have the p property like this, it works well. [{}] or [{"id":123}]
I'm breaking the filter in lines to make it easy to understand.
.p as $p
| .p[]?.product.productId as $pa
| .io[]
| select(.product.productId == ($pa) or .description == "product description x")
| .product.productId as $pid
| {"offerId": .offerId,
"description": .description,
"required":
"($p[] | select(.product.productId == $pid) | .required)",
"applied": false,
"amount": (if .prices | length == 0
then 0
elif .prices[0].amount != null
then .prices[0].amount
else .prices[0].amountPercentage
end)}
Input:
{
"p": null,
"io": [{
"offerId": 5593,
"description": "product description x",
"product": {
"productId": 393,
"description": "product description x 2",
"type": "Insurance"
},
"prices": [
{
"amount": null,
"amountPercentage": 4.13999987,
"status": "On"
}
]
}]
}
All I want is to be able to ignore the P when it is null or [].
*I'm aware about this literal expression "($p[] | select(.product.productId == $pid) | .required)"
jqplay.org/s/wYwKUFM2XR
Regards

Answer 1

E? is like try E catch empty, whereas what you seem to want is either try E catch null or perhapsE? // null
.p[]? is not the same as .p?[] or .p?[]?:
$ jq -n '[] | .p[]?'
jq: error (at <unknown>): Cannot index array with string "p"
$ jq -n '[] | .p?[]'
$
$ jq -n '[] | .p?[]?'
$
Specifically, .p[] is like .p | (try .[] catch empty), so there is nothing to stop the .p from raising an exception.
You might like to consider using try explicitly:
$ jq -n '[] | try .p[] catch null'
$