Json to CSV conversion with value as headers - json

Question

I have a below JSON file and need to convert to CSV file with some values as headers and below that values should get populated. Below is the sample json
{
"environments" : [ {
"dimensions" : [ {
"metrics" : [ {
"name" : "count",
"values" : [ "123" ]
}, {
"name" : "response_time",
"values" : [ "15.7" ]
}],
"name" : "abcd"
}, {
"metrics" : [ {
"name" : "count",
"values" : [ "456" ]
}, {
"name" : "response_time",
"values" : [ "18.7" ]
}],
"name" : "xyzz"
}
This is what I have tried already
jq -r '.environments[].dimensions[] | .name as $p_name | .metrics[] | .name as $val_name | if $val_name == "response_time" then ($p_name,$val_name, .values[])' input.json
Expected out as
name,count,response_time
abcd, 123, 15.7
xyzz, 456, 18.7

Answer 1

If the goal is to rely on the JSON itself to supply the header names in whatever order the "metrics" arrays present them,
then consider:
.environments[].dimensions
| ["name", (.[0] | .metrics[] | .name)], # first emit the headers
( .[] | [.name, (.metrics[].values[0])] ) # ... and then the data rows
| #csv

Answer 2

Generating the headers is easy, so I'll focus on generating the rest of the CSV.
The following has the advantage of being straightforward and will hopefully be more-or-less self-explanatory, at least with the jq manual at the ready. A tweak with an eye to efficiency follows.
jq -r '
# name,count,response_time
.environments[].dimensions[]
| .name as $p_name
| .metrics
| [$p_name]
+ map(select(.name == "count") | .values[0] )
+ map(select(.name == "response_time") | .values[0] )
| #csv
'
Efficiency
Here's a variant of the above which would be appropriate if the .metrics array had a large number of items:
jq -r '
# name,count,response_time
.environments[].dimensions[]
| .name as $p_name
| INDEX(.metrics[]; .name) as $dict
| [$p_name, $dict["count"].values[0], $dict["response_time"].values[0]]
| #csv
'