无法定位stack level too deep错误，求助排查哈希扁平化代码问题

Hey there! Let's break down why you're hitting that stack overflow issue and get your hash flattening function working correctly.

The Root Cause #

The problem is in your recursive call: you're passing the original hash instead of the nested value that you just confirmed is a Hash. This means every recursive call loops over the same top-level hash forever, leading to infinite recursion and the stack overflow error.

Look at this line in your code:

pathifize(hash,results, combined_key, b)

You should be passing value here, since that's the nested hash you need to process next.

Fixed Code #

Here's the corrected version of your function, with that critical fix plus a small tweak to make the return value explicit (since your original code would return the input hash instead of the accumulated results):

require 'active_support'
require 'active_support/core_ext'

def pathifize(hash, results = {}, current_key='', separator = ".")
  hash.each do |new_key, value|
    combined_key = [current_key, new_key].delete_if { |k| k.blank? }.join(separator)
    
    if value.is_a?(Hash)
      # Recurse on the nested value, not the original hash!
      pathifize(value, results, combined_key, separator)
    else
      results[combined_key] = value
    end
  end
  
  # Return the accumulated flattened results
  results
end

Testing It Out #

Let's verify with your example input:

pathifize({a: {b: 1}})
# => {"a.b"=>1}

And a more complex nested hash to confirm it handles deeper levels:

pathifize({x: 2, y: {z: 3, w: {v: 4}, u: 5}})
# => {"x"=>2, "y.z"=>3, "y.w.v"=>4, "y.u"=>5}

Quick Notes #

• I renamed the b parameter to separator for readability—this is optional, but makes the code easier to follow for anyone reading it later.
• The explicit return results at the end ensures the function gives back the flattened hash (without this, Hash#each would return the original input hash instead).
• Your use of delete_if { |k| k.blank? } works perfectly with ActiveSupport's blank? to handle the initial empty current_key correctly.

内容的提问来源于stack exchange，提问作者Arb