Get value if object or string if string in jq array

Question

I have a JSON object that looks like this:

[{"name":"NAME_1"},"NAME_2"]

I would like an output of

["NAME_1", "NAME_2"]

Some of the entries in the array are an object with a key "name" and some are just a string of the name. I am trying to extract an array of the names. Using

jq -cr '.[].name // []'

throws an error as it is trying to index.name of the string object. Is there a way to check if it is a string, and if so just use its value instead of.name?

Answer 1

You can use the type function which returns "object" for objects.

jq '.[] | if type == "object" then .name else . end' file.json

To get the output as array, just wrap the whole expression into [ ... ] .

Answer 2

echo '[{"name":"NAME_1"},"NAME_2"]' \
| jq '[ .[] | if (.|type) == "object" then .name else . end ]'

[
  "NAME_1"
  "NAME_2"
]

Ref:

• https://stedolan.github.io/jq/manual/#ConditionalsandComparisons
• https://stedolan.github.io/jq/manual/#type

---

As @LéaGris comments, a simpler version

jq '[ .[] | .name? // . ]' file

• https://stedolan.github.io/jq/manual/#ErrorSuppression/OptionalOperator:%3f
• https://stedolan.github.io/jq/manual/#Alternativeoperator://

Answer 3

Just use the error suppression operator with ? , map and scalars

jq 'map( .name?, scalars )'

Note that by using scalars , it is assumed that other than objects with name , all others are names of form NAME_* . If there are other strings as well, and you need to exclude some of them you might need to add some additional logic to do that. eg using startswith(..) with a string of your choice.

map( .name?, select( scalars | startswith("NAME") ) )

Demo

Answer 4

With your shown samples only, please try following jq code. Using tostream function here to get the required values from requirement.

jq -c '[.[] | tostream | if .[1] != null then .[1] else empty end]' Input_file