Nested hash iteration: How to iterate a merge over an ( (array of hashes) within a hash ) - ruby

Question

I'm trying to do as the title says. Here is my code:
school.each { |x| school[:students][x].merge!(semester:"Summer") }
I think I pinpointed the problem to the "[x]" above. If I substitute an array position such as "[2]" it works fine. How can make the iteration work?
If the info above is not enough or you'd like to offer a better solution, please see the details below. Thanks!
The error message I get:
file.rb:31:in []': no implicit conversion of Array into Integer (TypeError)
from file.rb:31:inblock in '
from file.rb:31:in each'
from file.rb:31:in'
The nested hash below before alteration:
school = {
:name => "Happy Funtime School",
:location => "NYC",
:instructors => [
{:name=>"Blake", :subject=>"being awesome" },
{:name=>"Ashley", :subject=>"being better than blake"},
{:name=>"Jeff", :subject=>"karaoke"}
],
:students => [
{:name => "Marissa", :grade => "B"},
{:name=>"Billy", :grade => "F"},
{:name => "Frank", :grade => "A"},
{:name => "Sophie", :grade => "C"}
]
}
I'm trying to append :semester=>"Summer" to each of the last four hashes. Here is what I'm trying to go for:
# ...preceding code is the same. Changed code below...
:students => [
{:name => "Marissa", :grade => "B", :semester => "Summer"},
{:name=>"Billy", :grade => "F", :semester => "Summer"},
{:name => "Frank", :grade => "A", :semester => "Summer"},
{:name => "Sophie", :grade => "C", :semester => "Summer"}
]
}

Answer 1

Just iterate over the students:
school[:students].each { |student| student[:semester] = "Summer" }
Or, using merge:
school[:students].each { |student| student.merge!(semester: "Summer") }

Answer 2

The issue is that when you do array.each {|x| do something}, x actually refers to each element in the array.
For example, in the first iteration of the loop,
x = {:name => "Marissa", :grade => "B"}
So what you are really doing is trying to reference:
school[:student][{:name => "Marissa", :grade => "B"}]
Which will not work
What you could do instead is create a for loop to track the index.
for i in 0 ... school[:student].count
school[:students][i].merge!(semester:"Summer")
end
Edit: Stefan's solution is much better than mine, but I will leave this up to show where you went wrong.

Answer 3

I would do as below using Hash#store :
require 'awesome_print'
school = {
:name => "Happy Funtime School",
:location => "NYC",
:instructors => [
{
:name => "Blake",
:subject => "being awesome"
},
{
:name => "Ashley",
:subject => "being better than blake"
},
{
:name => "Jeff",
:subject => "karaoke"
}
],
:students => [
{
:name => "Marissa",
:grade => "B"
},
{
:name => "Billy",
:grade => "F"
},
{
:name => "Frank",
:grade => "A"
},
{
:name => "Sophie",
:grade => "C"
}
]
}
school[:students].each{|h| h.store(:semester ,"Summer")}
ap school,:index => false,:indent => 10
output
{
:name => "Happy Funtime School",
:location => "NYC",
:instructors => [
{
:name => "Blake",
:subject => "being awesome"
},
{
:name => "Ashley",
:subject => "being better than blake"
},
{
:name => "Jeff",
:subject => "karaoke"
}
],
:students => [
{
:name => "Marissa",
:grade => "B",
:semester => "Summer"
},
{
:name => "Billy",
:grade => "F",
:semester => "Summer"
},
{
:name => "Frank",
:grade => "A",
:semester => "Summer"
},
{
:name => "Sophie",
:grade => "C",
:semester => "Summer"
}
]
}