fn:replace to return one string on iteration

Question

I am looking to implement a find and replace for a string from a document by using the key and value pair of a map. The code I currently have seems to be returning 2 strings because of 2 map values. I am looking to return one string with values in curly braces be replaced by the value in the map.

let $text:='On ${date} the value of alert is ${alerts}'
    let $params:= map:map()
    let $noop:=map:put($params,'date','TESTINGDATE')
    let $noop:=map:put($params,'alerts','TESTALERT')


    let $formatted-message:=for $keys in map:keys($params)
                            let $message:=fn:replace($text,fn:concat('\$\{',$keys,'\}'),map:get($params,$keys))
                            return $message

    return $formatted-message

Answer 1

You could use a recursive function:

declare function local:replace-all($text, $key, $rest, $params) 
{
  if (fn:empty($key)) then
    $text
  else
    local:replace-all(fn:replace($text, fn:concat('\$\{',$key,'\}'), map:get($params,$key)), 
                      fn:head($rest), 
                      fn:tail($rest), 
                      $params)

};

let $text:='On ${date} the value of alert is ${alerts}'
let $params:= map:map()
let $noop:=map:put($params,'date','TESTINGDATE')
let $noop:=map:put($params,'alerts','TESTALERT')
let $keys := map:keys($params)
return
  local:replace-all($text, fn:head($keys), fn:tail($keys), $params)

Or you could use fn:fold-left():

let $text:='On ${date} the value of alert is ${alerts}'
let $params:= map:map()
let $noop:=map:put($params,'date','TESTINGDATE')
let $noop:=map:put($params,'alerts','TESTALERT')
let $keys := map:keys($params)
return
  fn:fold-left(
    function($text, $keys) {
      let $key := fn:head($keys)
      return 
        fn:replace($text, fn:concat('\$\{',$key,'\}'), map:get($params,$key))
    },
    $text,
    $keys
  )

Both produce:

On TESTINGDATE the value of alert is TESTALERT