Json representation of SQL conditions

Question

Is there any method to convert a SQL condition to Json? I mean, I need to write something like this:

x > 5 and (y like '%b%' or z > 5) and b = true

as Json?

Answer 1

You could use jOOQ and Gson for that. Here's a quick and dirty example of how that could work:

new Gson()
    .newBuilder()
    .setPrettyPrinting()
    // Some jOOQ types can be serialised out of the box
    // For others, you might have to register adapters explicitly:
    .registerTypeHierarchyAdapter(
       Field.class, 
       (JsonSerializer<Field<?>>) (s, t, ctx) -> new JsonPrimitive(s.getName()))
    .create()
    .toJson(DSL.using(SQLDialect.DEFAULT)
       .parser()
       .parseCondition("x > 5 and (y like '%b%' or z > 5) and b = true"), 
       System.out
    );

The above prints:

{
  "operator": "AND",
  "conditions": [
    {
      "field1": "X",
      "field2": "5",
      "comparator": "GREATER"
    },
    {
      "operator": "OR",
      "conditions": [
        {
          "field1": "Y",
          "field2": "%b%",
          "comparator": "LIKE"
        },
        {
          "field1": "Z",
          "field2": "5",
          "comparator": "GREATER"
        }
      ]
    },
    {
      "field1": "B",
      "field2": "true",
      "comparator": "EQUALS"
    }
  ]
}

Of course, this is not very forward compatible, because it uses reflection to access jOOQ's internals. The names of your JSON objects (eg operator , conditions ) might change at any time, but it may still be good enough for you.

A future jOOQ version might offer more stable JSON exports of its expression tree: https://github.com/jOOQ/jOOQ/issues/9628

Disclaimer: I work for the company behind jOOQ.

Answer 2

Recently I found and used JsonLogic. It is very good approach as well. https://jsonlogic.com/