Deep Convert OpenStruct to JSON - ruby

Question

I have an OpenStruct that is nested with many other OpenStructs. What's the best way to deeply convert them all to JSON?
Ideally:
x = OpenStruct.new
x.y = OpenStruct.new
x.y.z = OpenStruct.new
z = 'hello'
x.to_json
// {y: z: 'hello'}
Reality
{ <OpenStruct= ....> }

Answer 1

There is no default methods to accomplish such task because the built-in #to_hash returns the Hash representation but it doesn't deep converts the values.
If a value is an OpenStruct, it's returned as such and it's not converted into an Hash.
However, this is not that complicated to solve. You can create a method that traverses each key/value in an OpenStruct instance (e.g. using each_pair), recursively descends into the nested OpenStructs if the value is an OpenStruct and returns an Hash of just Ruby basic types.
Such Hash can then easily be serialized using either .to_json or JSON.dump(hash).
This is a very quick example, with an update from #Yuval Rimar for arrays of OpenStructs:
def openstruct_to_hash(object, hash = {})
case object
when OpenStruct then
object.each_pair do |key, value|
hash[key] = openstruct_to_hash(value)
end
hash
when Array then
object.map { |v| openstruct_to_hash(v) }
else object
end
end
openstruct_to_hash(OpenStruct.new(foo: 1, bar: OpenStruct.new(baz: 2)))
# => {:foo=>1, :bar=>{:baz=>2}}

Answer 2

Fixes to above solution to handle arrays
def open_struct_to_hash(object, hash = {})
object.each_pair do |key, value|
hash[key] = case value
when OpenStruct then open_struct_to_hash(value)
when Array then value.map { |v| open_struct_to_hash(v) }
else value
end
end
hash
end

Answer 3

Here's yet another approach, modified from lancegatlin's answer. Also adding the method to the OpenStruct class itself.
class OpenStruct
def deep_to_h
each_pair.map do |key, value|
[
key,
case value
when OpenStruct then value.deep_to_h
when Array then value.map {|el| el === OpenStruct ? el.deep_to_h : el}
else value
end
]
end.to_h
end

Answer 4

in initializers/open_struct.rb:
require 'ostruct'
# Because #table is a instance variable of OpenStruct and Object#as_json returns Hash of instance variables.
class OpenStruct
def as_json(options = nil)
#table.as_json(options)
end
end
Usage:
OpenStruct.new({ a: { b: 123 } }).as_json
# Result
{
"a" => {
"b" => 123
}
}
Edit:
This seems to do almost the same thing (notice the keys are symbols instead of strings)
OpenStruct.new({ a: { b: 123 } }).marshal_dump
# Result
{
:a => {
:b => 123
}
}

Answer 5

Same function that can accept arrays as an input too
def openstruct_to_hash(object, hash = {})
case object
when OpenStruct then
object.each_pair do |key, value|
hash[key] = openstruct_to_hash(value)
end
hash
when Array then
object.map { |v| openstruct_to_hash(v) }
else object
end
end

Answer 6

None of the above worked for me with a copy and paste. Adding this solution:
require 'json'
class OpenStruct
def deep_to_h
each_pair.map do |key, value|
[
key,
case value
when OpenStruct then value.deep_to_h
when Array then value.map {|el| el.class == OpenStruct ? el.deep_to_h : el}
else value
end
]
end.to_h
end
end
json=<<HERE
{
"string": "fooval",
"string_array": [
"arrayval"
],
"int": 2,
"hash_array": [
{
"string": "barval",
"string2": "bazval"
},
{
"string": "barval2",
"string2": "bazval2"
}
]
}
HERE
os = JSON.parse(json, object_class: OpenStruct)
puts JSON.pretty_generate os.to_h
puts JSON.pretty_generate os.deep_to_h