Parsing JSON when fields are missing in some objects of an array

Guides Parsing
#1

If you’ve ever encountered an array like this, where the edition is missing from the second book, you might have noticed that a normal JSON parse will only yield 1 value instead of 2 (of which the second is empty).

{
   "book":[
      {
         "id":"444",
         "language":"C",
         "edition":"First",
         "author":"Dennis Ritchie "
      },
      {
         "id":"555",
         "language":"C++",
         "author":" Bjarne Stroustrup "
      }
   ]
}

This might cause you some trouble when trying to merge multiple lists later on, as they will have a different number of items. So I made a small script to show you an alternative way of doing this.

You basically want to parse every single object of the array, then perform a FOREACH loop and parse the values of each object, and finally add the formatted string to a master list.

Here’s the LoliCode

BLOCK:ConstantString
  value = "{\"book\":[{\"id\":\"444\",\"language\":\"C\",\"edition\":\"First\",\"author\":\"Dennis Ritchie \"},{\"id\":\"555\",\"language\":\"C++\",\"author\":\" Bjarne Stroustrup \"}]}"
  => VAR @json
ENDBLOCK

BLOCK:Parse
  input = @json
  jToken = "book[*]"
  RECURSIVE
  MODE:Json
  => VAR @books
ENDBLOCK

BLOCK:ConstantList
  value = []
  => CAP @output
ENDBLOCK

FOREACH book IN books
BLOCK:Parse
  input = @book
  jToken = "id"
  MODE:Json
  => VAR @id
ENDBLOCK

BLOCK:Parse
  input = @book
  jToken = "language"
  MODE:Json
  => VAR @language
ENDBLOCK

BLOCK:Parse
  input = @book
  jToken = "edition"
  MODE:Json
  => VAR @edition
ENDBLOCK

BLOCK:AddToList
  list = @output
  item = $"id: <id>, language: <language>, edition: <edition>"
ENDBLOCK
END

Ruri

4 Likes