How to serialize hylang s-expression into PostgreSQL json/json-b?

Question

We are trying to use hylang as DSL for some financial business flow. We were trying to use business rules as JSON, but switched to DSL using hy language. Now we need to persist s-expression items into postgreSQL as like previous JSON-B items. Is there a standard way to do this or we have to use text fields instead?

Previous:

  "conditions": {
    "all": [
        {
            "name": "order_create_date",
            "value": 1620675000,
            "operator": "greater_than_or_equal_to"
        },
        {
            "name": "order_create_date",
            "value": 1624217400,
            "operator": "less_than_or_equal_to"
        }
  }

Current:

(defn check_condition [params] (
                            and (> params.order_create_date "2021/06/22") (< params.order_create_date "2021/07/22"))

)

Answer 1

There are 2 solutions:

1. Using libraries like 'sexpdata' for parsing and unparsing S-Expresisons to/from Python list, and then using JSON plus some custom enc/dec.

2. Using pyparsing for parsing S-Expression into Python list and then using json.

   import pyparsing as pp
   import json
   
   LP = pp.Literal("(").suppress()
   RP = pp.Literal(")").suppress()
   String = pp.Word(pp.alphanums + '_,.#@<>=+=/*%[]')
   SingleQuoteString = pp.QuotedString(quoteChar="'", unquoteResults=False)
   DoubleQuoteString = pp.QuotedString(quoteChar='"', unquoteResults=False)
   QuotedString = SingleQuoteString | DoubleQuoteString
   Atom = String | QuotedString
   SExpr = pp.Forward()
   SExprList = pp.Group(pp.ZeroOrMore(SExpr | Atom))
   SExpr << (LP + SExprList + RP)
   
   
   def to_json(expr: str) -> str:
       return json.dumps(SExpr.parseString(expr).asList())
   
   
   def from_json(val: str) -> str:
       if isinstance(val, list):
           return f"({' '.join(from_json(e) for e in val)})"
       else:
           return str(val)