Select objects based on value of variable in object using jq

Adapted from this post on Processing JSON with jq, you can use the select(bool) like this:

$ jq '.[] | select(.location=="Stockholm")' json{  "location": "Stockholm",  "name": "Walt"}{  "location": "Stockholm",  "name": "Donald"}

To obtain a stream of just the names:

$ jq '.[] | select(.location=="Stockholm") | .name' json

produces:

"Donald""Walt"

To obtain a stream of corresponding (key name, "name" attribute) pairs, consider:

$ jq -c 'to_entries[]        | select (.value.location == "Stockholm")        | [.key, .value.name]' json

Output:

["FOO","Donald"]["BAR","Walt"]

I had a similar related question: What if you wanted the original object format back (with key names, e.g. FOO, BAR)?

Jq provides to_entries and from_entries to convert between objects and key-value pair arrays. That along with map around the select

These functions convert between an object and an array of key-value pairs. If to_entries is passed an object, then for each k: v entry in the input, the output array includes {"key": k, "value": v}.

from_entries does the opposite conversion, and with_entries(foo) is a shorthand for to_entries | map(foo) | from_entries, useful for doing some operation to all keys and values of an object. from_entries accepts key, Key, name, Name, value and Value as keys.

jq15 < json 'to_entries | map(select(.value.location=="Stockholm")) | from_entries'{  "FOO": {    "name": "Donald",    "location": "Stockholm"  },  "BAR": {    "name": "Walt",    "location": "Stockholm"  }}

Using the with_entries shorthand, this becomes:

jq15 < json 'with_entries(select(.value.location=="Stockholm"))'{  "FOO": {    "name": "Donald",    "location": "Stockholm"  },  "BAR": {    "name": "Walt",    "location": "Stockholm"  }}