Example 1: Reading a JSON file

This program reads JSON data from customers.json, then parses the file content to fill the program array custlist, converts the array back to a JSON string and writes a formatted JSON string to the standard output.

Note: The parse() method is enclosed in a TRY/CATCH block, to detect potential JSON format errors in the source file.

IMPORT util
MAIN
  DEFINE jsondata TEXT,
         custlist DYNAMIC ARRAY OF RECORD
            num INTEGER,
            name VARCHAR(40)
         END RECORD,
         tmp STRING
  LOCATE jsondata IN FILE "customers.json"
  TRY
    CALL util.JSON.parse( jsondata, custlist )
    DISPLAY "Array length = ", custlist.getLength()
    LET tmp = util.JSON.stringify(custlist)
    DISPLAY util.JSON.format( tmp )
  CATCH
    DISPLAY "ERROR:", STATUS
  END TRY
END MAIN

The file customers.json:

[
    {
        "num": 823,
        "name": "Mark Renbing"
    },
    {
        "num": 234,
        "name": "Clark Gambler"
    }
]

Note that the JSON file does not contain the name of the dynamic array (custlist), but starts directly with the JSON array in [ ] square brackets.