Ruby Serialize and DeSerialize Struct - ruby

Question

I'm trying to serialize an S3 Object so that I can deserialize at a later time. Deserialization is failing to grab the Object's class and is not grouping the object's variables. Here's my current code:
require 'yaml'
def serialize_array_of_objects(array, filename)
unless array.empty?
File.open(filename, "w+") do |f|
array.each { |element|
serialized_object = YAML::dump(element)
f.write(serialized_object)
}
end
end
end
Here's the contents of the file (redacted):
--- !ruby/struct:Aws::S3::Types::Object
key: file1.csv
last_modified: 2019-03-24 17:24:41.000000000 Z
etag: '"REDACTED"'
size: 41248
storage_class: STANDARD
owner:
--- !ruby/struct:Aws::S3::Types::Object
key: file2.csv
last_modified: 2019-04-24 15:30:41.000000000 Z
etag: '"REDACTED"'
size: 33527
storage_class: STANDARD
owner:
To deserialize the objects I'm using this code:
def serialized_file_to_array(filename)
array = []
File.open(filename, "r").each { |line|
array << YAML::load(line)
}
return array
end
My problem is that the object get's distorted on load. Here's the array now:
[nil, {"key"=>"file1.csv"}, {"last_modified"=>2019-03-24 17:24:41 UTC}, {"etag"=>"\"REDACTED\""}, {"size"=>41248}, {"storage_class"=>"STANDARD"}, {"owner"=>nil}, nil, {"key"=>"file2.csv"}, {"last_modified"=>2019-04-24 15:30:41 UTC}, {"etag"=>"\"REDACTED\""}, {"size"=>33527}, {"storage_class"=>"STANDARD"}, {"owner"=>nil}]
I need to be able to pull the object key values in the deserialized version.

Answer 1

The issue is you dump objects resulting in several lines in the yaml file, but you load back lines deserializing lines. Each line does not obviously contain the whole object, that’s why you get an array hashes (one per line) back.
You need to collect lines until the new object marker is there or to read the whole file content, split it into objects with e. g. regular expression and load split objects.
The first approach would be like:
File.readlines(FILE).
each_with_object([[], []]) do |line, (inner_acc, outer_acc)|
if line.start_with?('---')
outer_acc << YAML.load(inner_acc.join) unless inner_acc.empty?
inner_acc.clear << line
else
inner_acc << line
end
end.tap do |inner_acc, outer_acc|
break outer_acc << YAML.load(inner_acc.join) # last chunk
end
With regular expression, it should be even simpler.