How to make String with Placeholders?

Do You mean string interpolation?

Because it does…

iex> id = 223344
223344
iex> lang = "eng"
"eng"
iex> type = "json"
"json"
iex> url = "http: // somesite. com/?i=#{id}&lang=#{lang}&type=api&api_v=1&api_type=#{type}"
"http: // somesite. com/?i=223344&lang=eng&type=api&api_v=1&api_type=json"

Now in your result #223344… It would be ##{id} if You really want #

Maybe not the simplest option but also works

iex(1)> template = "http://somesite.com/?i=#<%=id%>&lang=#<%=language%>&type=api&api_v=1&api_type=#<%=data_type%>"
"http://somesite.com/?i=#<%=id%>&lang=#<%=language%>&type=api&api_v=1&api_type=#<%=data_type%>"
iex(2)> EEx.eval_string(template, [id: 1, language: "pt-BR", data_type: "json"])
"http://somesite.com/?i=#1&lang=#pt-BR&type=api&api_v=1&api_type=#json"

Almost…it works in iex, but no in code… this is that I mean:

def prit_url(id, lang, url) do
   IO.puts url
do

How this function should look like, so user’s ID and LANG would go to URL ?

Hm… yeap, looks like a temporary solutionm but I wonder, maybe there is something nicer ?

If You can have an url like this…

iex> url = "http://somesite.com/?i=%{id}&lang=%{language}&type=api&api_v=1&api_type=%{data_type}"

I just changed # for % to have a valid string…

Then You could

iex> url |> String.split("%")                                                                    
["http://somesite.com/?i=", "{id}&lang=",
 "{language}&type=api&api_v=1&api_type=", "{data_type}"]

And on each substring starting with {} You would…

id=223344
s = "{id}&lang=" 
s |> String.replace(~r/^{.}/, id)

But it is a little bit hackish…

Yep…
Well, I know that I can parse url…

The point is that this solution is not flexible…
This would work good on static urls, that do not change…

In cases where url can be any, probably it is better to use cpgo’s solution.
In my case I cant know in advance all possible urls, but I can tell user use the fallowing layout… and the test if user provides url according to layout and if it is matches then execute as a template…

Thank you guys for help !

You should generally be using the URI module to deal with URLs: URI — Elixir v1.20.2
That will handle the escaping, otherwise you will have plenty of surprises with strange data.

One way is with Michał Muskała’s Format library GitHub - michalmuskala/format: A simple string formatter for Elixir · GitHub. I’m not sure if there’s any documentation, but you can do:

def print_url(id, language, url) do
  url
  |> Format.compile()
  |> Format.string(id: id, language: language)
  |> IO.puts()
end

where url is a string that contains {id} and {language}, which get replaced by the corresponding values specified in Format.string.

My personal syntactic preference would be

...
  |> Format.string([id: id, language: language])
...

Hi jakemorrison,

Thank you for a good point. You are absolutely right.