Update fields from string in JQ - json

Question

I have a bash $string containing the values: abc,def and a file.json looking like this:
[
{
"loc": "51.12345, 12.12345",
"city": "CityName1"
},
{
"loc": "65.12345, 15.12345",
"city": "CityName2"
}
]
I'm trying to update the city field with the values from the string to get this result:
[
{
"loc": "51.12345, 12.12345",
"city": "abc"
},
{
"loc": "65.12345, 15.12345",
"city": "def"
}
]
I'm trying this code but it doesn't work, any suggestions?
string="abc,def"; jq --arg variable "$string" '.city = $string' file.json

Answer 1

You're looking for something like this:
$ string=abc,def
$ jq --arg cities "$string" '[., ($cities / ",")] | transpose | map(.[0] + {city: .[1]})' file.json
[
{
"loc": "51.12345, 12.12345",
"city": "abc"
},
{
"loc": "65.12345, 15.12345",
"city": "def"
}
]
$

Answer 2

With nodejs:
> var json = [
... {
... "loc": "51.12345, 12.12345",
... "city": "CityName1"
... },
... {
... "loc": "65.12345, 15.12345",
... "city": "CityName2"
... }
... ]
> var c = 0
> ["abc", "def"].forEach(n => json[c++].city = n)
> console.log(JSON.stringify(json, null, 4))
[
{
"loc": "51.12345, 12.12345",
"city": "abc"
},
{
"loc": "65.12345, 15.12345",
"city": "def"
}
]
From a script :
#!/bin/bash
node<<EOF | sponge file.json
var json = $(< file.json)
var c = 0;
["abc", "def"].forEach(n => json[c++].city = n)
console.log(JSON.stringify(json, null, 4))
EOF
output file:
[
{
"loc": "51.12345, 12.12345",
"city": "abc"
},
{
"loc": "65.12345, 15.12345",
"city": "def"
}
]

Answer 3

Using reduce would be another way. Same lengths provided, it allows iterating over the entries along with their indices, which can then be used to access the input array.
string="abc,def"
jq --arg var "$string" '
reduce ($var / "," | to_entries)[] as {$key, $value} (.;
.[$key].city = $value
)
'
I'm getting an error with jq version 1.4
To make this approach compatible with jq 1.4, replace the variable destructuring with a plain variable, and access its parts later, e.g.
string="abc,def"
jq --arg var "$string" '
reduce ($var / "," | to_entries)[] as $item (.;
.[$item.key].city = $item.value
)
'
Output:
[
{
"loc": "51.12345, 12.12345",
"city": "abc"
},
{
"loc": "65.12345, 15.12345",
"city": "def"
}
]