dotfiles/notes/shell/jq_json_query_parser.md

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2023-12-23 20:13:52 -07:00
# JQ, stream json parser
`jq` is a minimal json parser that's pretty useful in shell scripts. It can
quickly filter json outputs for reading something. Most languages, for example
js, have much faster json-parsers built-in, so it's better to use those when
possible
Json output usually comes in one of two forms, either a single json object, or
an array of jsons. To extract jsons we can use
```bash
yabai -m query --windows --window | jq '.' # Already a single json
yabai -m query --windows | jq '.[]' # Iterates through array
```
`jq` takes in a filter on the right side, after a pipe-like separator. The
output will just be the that value for single fields
```bash
yabai -m query --windows | jq '.[] | .id' # Id of every window
yabai -m query --windows | jq '.[] | .id, .app' # ID and name
yabai -m query --windows | jq '.[] | .frame.x' # x field in frame field
```
Your output can be either raw values, json objects, or arrays:
```bash
yabai -m query --windows | jq '.[] | .id' # Raw id
yabai -m query --windows | jq '.[] | { id: .id }' # Id objects
yabai -m query --windows | jq '.[] | [{ id: .id }]' # Id objects in individual arrays
yabai -m query --windows | jq '[.[] | { id: .id }]' # Id objects in one array
```