I have the following code:
default = {:id => 0, :detail =>{:name=>"Default", :id => ""}}
employees = {}
nr = (0..3).to_a
nr.each do |n|
employee = default
employee[:id] = n
employee[:detail][:name] = "Default #{n}"
employee[:detail][:id] = "KEY-#{n}"
employees[n] = employee
end
puts employees
I expect the values for the key :id
in :detail
hash to be KEY-0
, KEY-1
, KEY-2
.
You will need marshall your default in order to copy
default = {id: 0, detail: {name: "Default", id:""}}
employees = {}
4.times do |n|
employees[n] = Marshal.load(Marshal.dump(default))
employees[n][:id] = n
employees[n][:detail][:name] = "Default #{n}"
employees[n][:detail][:id] = "KEY-#{n}"
end
puts employees
The output is
{0=>{:id=>0, :detail=>{:name=>"Default 0", :id=>"KEY-0"}}, 1=>{:id=>1, :detail=>{:name=>"Default 1", :id=>"KEY-1"}}, 2=>{:id=>2, :detail=>{:name=>"Default 2", :id=>"KEY-2"}}, 3=>{:id=>3, :detail=>{:name=>"Default 3", :id=>"KEY-3"}}}
You can read this post Cloning an array with its content
ADDED
And here you have an reduce version and should be faster if you want.
employees = {}
4.times { |n| employees[n]={id: n, detail: {name: "Default #{n}", id:"KEY-#{n}"}} }
puts employees
You need only change:
default = { :id=>0, :detail=>{ :name=>"Default", :id=>"" } }
to
def default
{}.merge(:id=>0, :detail=>({}.merge(:name=>"Default", :id=>"")))
end
but, hey, while we're at it we may as well Ruby-ize the rest:
employees = (0..3).map do |n|
employee = default
employee[:id] = n
employee[:detail][:name] = "Default #{n}"
employee[:detail][:id] = "KEY-#{n}"
employee
end
#=> [{:id=>0, :detail=>{:name=>"Default 0", :id=>"KEY-0"}},
# {:id=>1, :detail=>{:name=>"Default 1", :id=>"KEY-1"}},
# {:id=>2, :detail=>{:name=>"Default 2", :id=>"KEY-2"}},
# {:id=>3, :detail=>{:name=>"Default 3", :id=>"KEY-3"}}]
Let's confirm we are making deep copies of default
:
employees[0][:detail][:id] = "cat"
employees
#=> [{:id=>0, :detail=>{:name=>"Default 0", :id=>"cat"}},
# {:id=>1, :detail=>{:name=>"Default 1", :id=>"KEY-1"}},
# {:id=>2, :detail=>{:name=>"Default 2", :id=>"KEY-2"}},
# {:id=>3, :detail=>{:name=>"Default 3", :id=>"KEY-3"}}]
You'd more commonly see this written:
employees = (0..3).map do |n|
default.merge(:id=>n, :detail=>{:name=>"Default #{n}", :id=>"KEY-#{n}"})
end
#=> [{:id=>0, :detail=>{:name=>"Default 0", :id=>"cat"}},
# {:id=>1, :detail=>{:name=>"Default 1", :id=>"KEY-1"}},
# {:id=>2, :detail=>{:name=>"Default 2", :id=>"KEY-2"}},
# {:id=>3, :detail=>{:name=>"Default 3", :id=>"KEY-3"}}]
As suggested by other answers, you could to this:
class Object
def deep_copy
Marshal.load(Marshal.dump(self))
end
end
Then you could write:
default = { :id=>0, :detail=>{ :name=>"Default", :id=>"" } }
employees = (0..3).map do |n|
default.deep_copy.merge(:id=>n, :detail=>{:name=>"Default #{n}",
:id=>"KEY-#{n}"})
end
#=> [{:id=>0, :detail=>{:name=>"Default 0", :id=>"KEY-0"}},
# {:id=>1, :detail=>{:name=>"Default 1", :id=>"KEY-1"}},
# {:id=>2, :detail=>{:name=>"Default 2", :id=>"KEY-2"}},
# {:id=>3, :detail=>{:name=>"Default 3", :id=>"KEY-3"}}]
This has the advantage that, if you change default
, no other changes are needed.
You are making a shallow copy in each iteration, ie each time each copy is overridden with the values calculated in the last iteration. You can try the following for you hash-within-hash default pattern to make a deep copy:
employee = Marshal.load(Marshal.dump(default))
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