Output semicolon-separated string - json

Question

Lets say we have this file:
{
"persons": [
{
"friends": 4,
"phoneNumber": 123456,
"personID": 11111
},
{
"friends": 2057,
"phoneNumber": 432100,
"personID": 22222
},
{
"friends": 50,
"phoneNumber": 147258,
"personID": 55555
}
]
}
I now want to extract the phone numbers of the persons 11111, 22222, 33333, 44444 and 55555 as a semicolon-separated string:
123456;432100;;;147258
While running
cat persons.txt | jq ".persons[] | select(.personID==<ID>) | .phoneNumber"
once for each <ID> and glueing the results together with the ; afterwards works, this is terribly slow, because it has to reload the file for each of the IDs (and other fields I want to extract).
Concatenating it in a single query:
cat persons.txt | jq "(.persons[] | select(.personID==11111) | .phoneNumber), (.persons[] | select(.personID==22222) | .phoneNumber), (.persons[] | select(.personID==33333) | .phoneNumber), (.persons[] | select(.personID==44444) | .phoneNumber), (.persons[] | select(.personID==55555) | .phoneNumber)"
This also works, but it gives
123456
432100
147258
so I do not know which of the fields are missing and how many ; I have to insert.

Answer 1

With your sample input in input.json, and using jq 1.6 (or a jq with INDEX/2), the following invocation of jq produces the desired output:
jq -r --argjson ids '[11111, 22222, 33333, 44444, 55555]' -f tossv.jq input.json
assuming tossv.jq contains the program:
INDEX(.persons[]; .personID) as $dict
| $ids
| map( $dict[tostring] | .phoneNumber)
| join(";")
Program notes
INDEX/2 produces a JSON object that serves as a dictionary. Since JSON keys must be strings, tostring must be used in line 3 above.
When using join(";"), null values effectively become empty strings.
If your jq does not have INDEX/2, then now might be a good time to upgrade. Otherwise you can snarf its definition by googling: jq "def INDEX" builtin.jq

Answer 2

Unfortunately I couldn't test if peak's answer works since I only have jq 1.5. Here's what I came up with yesterday evening:
For each semicolon, add the following query
(\";\" as \$a | \$a)
Resulting command (abstract):
cat persons.txt | jq "(<1's phone number>), (\";\" as \$a | \$a),
(<2's phone number>), (\";\" as \$a | \$a), ..."
Resulting command (concrete):
cat persons.txt | jq "(.persons[] | select(.personID==11111) | .phoneNumber), (\";\" as \$a | \$a),
(.persons[] | select(.personID==22222) | .phoneNumber), (\";\" as \$a | \$a),
(.persons[] | select(.personID==33333) | .phoneNumber), (\";\" as \$a | \$a),
(.persons[] | select(.personID==44444) | .phoneNumber), (\";\" as \$a | \$a),
(.persons[] | select(.personID==55555) | .phoneNumber)"
Result:
123456
";"
432100
";"
";"
";"
147258
Delete the newlines and ":
<commandAsAbove> | tr --delete "\n\""
Result:
123456;432100;;;147258
Do not get me wrong, this is far uglier than peak's answer, but it worked for me yesterday.

Answer 3

Without jq solution:
for i in $(seq 11111 11111 55555)
do
string=$(grep -B1 "$i" persons.txt | head -1 | sed 's/.* \(.*\),/\1/g')
echo "$string;" >> output
done
cat output | tr -d '\n' | rev | cut -d';' -f2- | rev > tmp && mv tmp output
This little script will yield the result you want and you can adapt it quickly if the input data varies
cat output
123456;432100;;;147258