What is the right formula for this Enum.reduce and String.replace combination?

Questions / Help
1

In the code below structList is a list of structs with each key being a string in a template and the value being the replacement.

%ParamStruct{default: "Greater London", description: "Region",
 key: "ca_cert_subj_state", label: "State/County", order: 99, required: false,
 value: "Greater London"}

So in the one above the key is ca_cert_subj_state and value is Greater London

This is the string in which the replacements are made:

sslCmd = """
openssl req -x509 -new -nodes -sha256 \
 -key {{key-file-pass}}.key \
 -days 3650 \
 -out {{key-file-pass}}.pem \
 -subj ""\
/C={{ca_cert_subj_country}}\
/ST={{ca_cert_subj_state}}\
/L={{ca_cert_subj_location}}\
/O={{ca_cert_subj_organization}}\
/OU={{ca_cert_subj_org_unit}}\
/CN={{ca_cert_subj_common_name}}\
/emailAddress={{ca_cert_email}}\
"""

The following code is supposed to accumulate the result of changing the strings in sslCmd but clearly doesn’t work. I am not sure how it should recurse or iterate. Any ideas?

Enum.reduce(structList, sslCmd, fn(x, sslCmd) -> 
     sslCmd = String.replace(sslCmd, "{{#{x.key}}}", x.value)
  end
)
2

Try

Enum.reduce(structList, sslCmd, fn(x, sslCmd) -> 
   String.replace(sslCmd, "{{#{x.key}}}", x.value)
end)

EDIT: = operator returns the value anyway, so just ignore my post, sorry.

3

Do you assign or return the return value of got snippet of are you relying on mutation of sslCmd? If the later, remember that there is no such thing in elixir

4

The assignment to sslCmd does not belong in the reduce function. It doesn’t change on account immutability. When assigned to the outcome of the Enum it works.

5

I have the Enum.reduce method working. This time I want to make make recursive calls over the list with this replace_string function. Is it all okay or are there some cases I have missed?

  def replace_string(subject, []), do: subject
      
  def replace_string(subject, [head | tail]) do
    replace_string(String.replace(subject, "{{#{head.key}}}", head.value),tail)
  end

I access this via

IO.puts "called via replace_string" <> " - " <> ProcessList.replace_string(sslCmd, structList)

I have a feeling it is not as complete as it should be. Any critiques?