I would like to know how to use jq to extract patterns from a .json file

echo '{"parts": [{"name":"core","items":"garbage with ITEM1 ITEM2 and more"},{"name":"misc","items":"ITEM3 ITEM4 ITEM5 bla bla"} ]}' | jq '.parts | .[] | .items |=split(" ")'
{
  "name": "core",
  "items": [
    "garbage",
    "with",
    "ITEM1",
    "ITEM2",
    "and",
    "more"
  ]
}
{
  "name": "misc",
  "items": [
    "ITEM3",
    "ITEM4",
    "ITEM5",
    "bla",
    "bla"
  ]
}

I think in splitting the items, but I don't know how to extract each ITEMx.

I want to obtain this output:

{ "core","ITEM1" }
{ "core","ITEM2" }
{ "misc","ITEM3" } 
{ "misc","ITEM4" }
{ "misc","ITEM5" }  

CodePudding user response：

Your desired output is not valid JSON.

Do you want the words form an array under the value of the .name field?

jq '.parts[] | {(.name): (.items | split(" "))}'

{
  "core": [
    "garbage",
    "with",
    "ITEM1",
    "ITEM2",
    "and",
    "more"
  ]
}
{
  "misc": [
    "ITEM3",
    "ITEM4",
    "ITEM5",
    "bla",
    "bla"
  ]
}

Demo

Or do you want each word to form a separate object?

jq '.parts[] | (.items | split(" "))[] as $word | {(.name): $word}'

{"core":"garbage"}
{"core":"with"}
{"core":"ITEM1"}
{"core":"ITEM2"}
{"core":"and"}
{"core":"more"}
{"misc":"ITEM3"}
{"misc":"ITEM4"}
{"misc":"ITEM5"}
{"misc":"bla"}
{"misc":"bla"}

Demo

To only capture words that match the regex ITEM\d , you could employ the scan function instead of splitting:

jq '.parts[] | {(.name): .items | scan("ITEM\\d ")}'

{"core":"ITEM1"}
{"core":"ITEM2"}
{"misc":"ITEM3"}
{"misc":"ITEM4"}
{"misc":"ITEM5"}

Demo

CodePudding user response：

Building on your attempt, we could try:

.parts
| .[]
| .items |= (split(" ") | map(select(test("ITEM"))))
| {(.name): .items[]}

This produces a stream of objects such as {"core":"ITEM1"}. If you really want the non-JSON output shown in the Q, it's easy enough to add the additional step.