Replace Sibling Value in YAML file using Ruby - ruby

Question

I have a yaml file with hundrends of stores. Here is an example:
- store_number: "1"
title_tag: "Title tag for store 1"
meta_description: "Description of store 1"
store_details: "Details of store 1"
find_us:
- store_number: "2"
title_tag: "Title tag for store 2"
meta_description: "Description of store 2"
store_details: "Details of store 2"
find_us:
I need to loop through each of these, compare the store number, and if it matches, add a value to the find_us key.
I've been able to search the file using this:
stores_file = YAML.load_file('_data/stores.yml')
stores_file.select do |store|
if store['store_number'] == '1'
puts store
end
end
This prints as expected:
{"store_number"=>"1", "title_tag"=>"Title tag for store 1", "meta_description"=>"Description of store 1", "store_details"=>"Details of store 1", "find_us"=>nil}
I have two problems, I don't know how to find a sibling (find_us in this case), and I don't know how to write to the find_us key.

Answer 1

Use YAML::Store
With just a little refactoring, you can essentially treat your YAML file as a transactional flat-file database using YAML::Store from the Ruby Standard Library. In order to iterate, though, you will probably need to ensure you have a single root in your YAML data store, rather than an array of hashes as you appear to have now. For example, given:
# _data/stores.yml
---
stores:
- store_number: "1"
title_tag: "Title tag for store 1"
meta_description: "Description of store 1"
store_details: "Details of store 1"
find_us:
- store_number: "2"
title_tag: "Title tag for store 2"
meta_description: "Description of store 2"
store_details: "Details of store 2"
find_us:
require 'yaml/store'
#db = YAML::Store.new '_data/stores.yml'
def update_find_us_for store_number, value
# coerce arguments to String objects
store_number, value = [store_number, value].map &:to_s
# completed transactions write the results back to the
# YAML data store for you
#db.transaction do
#db['stores'].each do |store|
store['find_us'] = value if store['store_number'] == store_number
end
end
end
update_find_us_for 1, 'foo'
Validate Expected Results
Validate in IRB
If you ran the code above in irb, you can validate that you made the changes you expected with pp _.first, which should print:
{"store_number"=>"1",
"title_tag"=>"Title tag for store 1",
"meta_description"=>"Description of store 1",
"store_details"=>"Details of store 1",
"find_us"=>"foo"}
Validate Programmatically
You can get at the changed data through instance variables, too. For example:
#db.instance_variable_get(:#table)['stores'].first.fetch 'find_us'
#=> "foo"
Validate at Shell Prompt
If you'd rather validate the stores.yml file directly, then from the Bash shell:
grep -A4 "store_number: '1'" _data/stores.yml
- store_number: '1'
title_tag: Title tag for store 1
meta_description: Description of store 1
store_details: Details of store 1
find_us: foo

Answer 2

When you load the YAML you end up with an array of hashes:
stores_file.class #=> Array
stores_file.first.class #=> Hash
So, you can loop, change the values according to your needs and save back the file.
Here I'm using a different file as destination.
stores_file.each do |store|
if store['store_number'] == '1'
store['find_us'] = 'here'
end
end
destination_file = 'SO00123_.yml'
File.open(destination_file,"w") do |file|
file.write stores_file.to_yaml
end
The resulting file is like:
---
- store_number: '1'
title_tag: Title tag for store 1
meta_description: Description of store 1
store_details: Details of store 1
find_us: here
- store_number: '2'
title_tag: Title tag for store 2
meta_description: Description of store 2
store_details: Details of store 2
find_us:

Answer 3

Create a test YAML file
str =<<~END
- store_number: "1"
title_tag: "Title tag for store 1"
meta_description: "Description of store 1"
store_details: "Details of store 1"
find_us:
- store_number: "2"
title_tag: "Title tag for store 2"
meta_description: "Description of store 2"
store_details: "Details of store 2"
find_us:
END
FILE_NAME = 't.yml'
File.write(FILE_NAME, str)
#=> 302
Define parameters
target_store = "2"
find_us_value = "whoa"
Read the YAML file and convert it to an array of hashes
require 'yaml'
arr = YAML.load(File.read(FILE_NAME))
#=> [{"store_number"=>"1", "title_tag"=>"Title tag for store 1",
# "meta_description"=>"Description of store 1",
# "store_details"=>"Details of store 1", "find_us"=>nil},
# {"store_number"=>"2", "title_tag"=>"Title tag for store 2",
# "meta_description"=>"Description of store 2",
# "store_details"=>"Details of store 2", "find_us"=>nil}]
Determine the index of the hash in arr whose value for the key "store_number" equals the value of target_store
i = arr.index { |h| h["store_number"] == target_store }
#=> 1
Update the hash arr[i]
After confirming that i is not nil,
arr[i]["find_us"] = find_us_value
#=> "whoa"
Confirm:
arr
#=> [{"store_number"=>"1", "title_tag"=>"Title tag for store 1",
# "meta_description"=>"Description of store 1",
# "store_details"=>"Details of store 1", "find_us"=>nil},
# {"store_number"=>"2", "title_tag"=>"Title tag for store 2",
# "meta_description"=>"Description of store 2",
# "store_details"=>"Details of store 2", "find_us"=>"whoa"}]
Convert the updated array arr to a YAML string and write that string to file
File.write(FILE_NAME, arr.to_yaml)
#=> 299
Confirm:
puts File.read(FILE_NAME)
---
- store_number: '1'
title_tag: Title tag for store 1
meta_description: Description of store 1
store_details: Details of store 1
find_us:
- store_number: '2'
title_tag: Title tag for store 2
meta_description: Description of store 2
store_details: Details of store 2
find_us: whoa
Note that YAML uses three dashes (“---”) to separate directives from the document content. This also serves to signal the start of a document if no directives are present.