Elixir integer list to string causes (UnicodeConversionError) invalid code point - string-interpolation

Question

The problem
I need to create a string interpolating a list of integers in it.
"""
SomeQuery {
someQuery(articleIds: #{inspect article_ids}) {
edges {
node {
id
}
}
}
}
"""
Failing example
For example, the list [725553234] makes the example above to fail:
article_ids = [725553234]
"""
SomeQuery {
someQuery(articleIds: #{article_ids}) {
edges {
node {
id
}
}
}
}
"""
** (exit) an exception was raised:
** (UnicodeConversionError) invalid code point 725553234
(elixir) lib/list.ex:839: List.to_string/1
(commsapp_api) lib/my_project/client.ex:70: CommsappApi.News.Clients.CommunicationMs.Client.articles_feed/3
System
Erlang/OTP 20 [erts-9.3] [source] [64-bit] [smp:8:8] [ds:8:8:10]
[async-threads:10] [hipe] [kernel-poll:false] [dtrace]
Elixir 1.6.3 (compiled with OTP 20)
Tried solutions
It tried the following:
Using inspect is not working: articleIds: #{inspect(article_ids)}
Using the IO.inspect with the :char_lists opt with :as_list: IO.inspect(article_ids, char_lists: :as_lists
Trying to join the integer list as string with: articleIds: [#{Enum.join(article_ids, ", ")}]
Interpolating the integers parsed to string with: Enum.map(article_ids, &Integer.to_string/1) |> Enum.join(", ")
I tried using a single line instead of a multiline string, not working
Many things I don't remember after trying different solutions... >.<
Guesses
The problem comes when using the brackets in the string, Elixir treats the interporlation as a list and raises the error because it cannot find the codepoints.
Ideas?
Thanks in advance!

Answer 1

In the documentation on strings, binaries and charlists, the charlists are defined as a list of point codes, i.e. integers. The code
article_ids = [725553234]
"#{article_ids}"
attempts to print the character which point code is 725553234. This point code is not defined and you get the error. Replace 725553234 by 65 and you should get an A character.
To interpolate your list of integers, you may want to do things like this:
iex(5)> a=[65, 66, 67]
'ABC'
iex(6)> "#{Enum.map(a, fn(c) -> Integer.to_string(c)<>" " end)}"
"65 66 67 "
BTW, if you look at list [65, 66, 67] is interpreted as 'ABC'.

Answer 2

By using Enum.join return string and separate integer by ","
Enum.join(list, ",")
or using Enum.map return as list by changing every integer value to string
Enum.map(list, &Integer.to_string/1)
list = [1, 2, 3, 4]
Enum.join(list, ",") -> "1,2,3,4"
Enum.map(list, &Integer.to_string/1) -> ["1", "2", "3", "4"]