Ruby hash nesting
I have a method that selects all rows from my table like this:
smtp_status_raw = my_table.select(:message, :is_valid, :hostname).map { |h| h.values }
This returns an array that looks like this:
[{:message=>"blah", :is_valid=>true, :hostname=>"1"}, {:message=>"blah", :is_valid=>true, :hostname=>"2"}, {:message=>"blah", :is_valid=>true, :hostname=>"3}]
Using the information above, I want to create a hash that looks like this:
{
:node_status =>
{
{:hostname => "1", :message: "blah"},
{:hostname => "2", :message: "blah"},
{:hostname => "3", :message: "blah"}
}
}
First of all, my question is - is it possible to create a hash like above? In the above Sequel request example, I have three objects that represent three separate nodes and I want to add those three nodes to the key :node_status
. Is it possible? If this is not a valid hash, then what is the alternative?
Second, this is what I tried:
# Initialize the hash
smtp_status_hash = { :node_status: => nil }
I've initialized a hash smtp_status_hash
with a key node_status
, but I'm not sure how to nest the query results.
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This is not a valid hash because you have 3 values but no keys in the sub-step :node_status
. You can do something like:
smtp_status_raw = [
{:message=>"blah", :is_valid=>true, :hostname=>"1"},
{:message=>"blah", :is_valid=>true, :hostname=>"2"},
{:message=>"blah", :is_valid=>true, :hostname=>"3"}
]
{
node_status: smtp_status_raw.collect do |hash|
hash.reject { |key, value| key == :is_valid }
end
}
to get the values in :node_status
as an array:
{
:node_status=>[
{:message=>"blah", :hostname=>"1"},
{:message=>"blah", :hostname=>"2"},
{:message=>"blah", :hostname=>"3"}
]
}
Or you could do something like:
{
node_status: smtp_status_raw.collect do |hash|
[hash[:hostname], hash[:message]]
end.to_h
}
which sets up a sub-hash with key
being :hostname
and value
:message
:
{
:node_status=>{
"1"=>"blah",
"2"=>"blah",
"3"=>"blah"
}
}
or if you had more keys that you wanted to keep:
{
node_status: smtp_status_raw.collect do |hash|
[hash[:hostname], hash.reject { |key, value| key == :is_valid }]
end.to_h
}
which is still the hash where it key
is :hostname
, but value
has a different hash:
{
:node_status=>{
"1"=>{:message=>"blah", :hostname=>"1"},
"2"=>{:message=>"blah", :hostname=>"2"},
"3"=>{:message=>"blah", :hostname=>"3"}
}
}
To set key values after creation Hash
, you can do something like:
smtp_status_hash = { node_status: nil }
smtp_status_hash[:node_status] = "Whatever you want here"
You can read more about Hash
and its methods and how you can select
both reject
save or delete keys from a hash. Hashes, although they are the structure of the dictionary and should always have key
one value
, although this value may be Array
different Hash
.
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