How to loop through a nested array and retrieve values - ruby

Question

I have the following array:
my_tst = [
[
{
"name": "shield",
"version": "8.6.3"
},
{
"name": "bosh-dns",
"version": "1.17.0"
},
{
"name": "nessus_agent",
"version": "1.0.24"
},
{
"name": "node-exporter",
"version": "4.2.0"
},
{
"name": "syslog",
"version": "11.6.1"
}
],
[
{
"name": "shield",
"version": "8.6.3"
},
{
"name": "bosh-dns",
"version": "1.16.0"
},
{
"name": "nessus_agent",
"version": "1.0.24"
},
{
"name": "node-exporter",
"version": "4.2.0"
},
{
"name": "syslog",
"version": "11.6.1"
}
]
]
I am trying to loop through the array and output only the values of name.
I used this loop:
my_tst["name"].each do |run|
p run
end
The loop is returning an Error:
TypeError: no implicit conversion of String into Integer
How do I output all values in the nested array?

Answer 1

You're trying to use [] in an array, which is meant to be used passing a numeric parameter in order to access its elements by their index. You're passing a string, which is the way you get values from hashes, and there's the problem.
You have an array of arrays containing hashes (with an interesting indentation), so in that case you need to first iterate the "main" array, to be able to get the hashes over each array.
This is one way you can achieve that:
my_tst.each_with_object([]) do |e, arr|
e.each { |f| arr << f[:name] }
end
# ["shield", "bosh-dns", "nessus_agent", "node-exporter", "syslog", "shield", "bosh-dns", "nessus_agent", "node-exporter", "syslog"]
Or:
data.flat_map do |e|
e.map { |f| f[:name] }
end
Anyway, there's going to be a nested iteration.