[FEATURE]Add PPL `JSON` extended functions support

[YANG-DB]

Is your feature request related to a problem?
We need to enhance OpenSearch PPL (Piped Processing Language) by adding support for JSON-based operations. This extension will provide users with powerful tools to manipulate and analyze JSON data within PPL queries.

Proposed New Functions

1. json_object(): Creates a JSON object from existing key/value pairs.

   ... | eval person = json_object("name", "John", "age", 30)

2. json(): Evaluates whether a value can be parsed as JSON. Returns the value if valid, null otherwise.

   ... | eval result = json('{"name":"John","age":30}')

3. json_append(): Appends elements to the contents of a valid JSON object.

   ... | eval person = json_object("name", "John"), extended_person = json_append(person, "city", "New York")

4. json_array(): Creates a JSON array using a list of values.

   ... | eval json_list = json_array("apple", "banana", "cherry")

5. json_array_to_mv(): Maps the elements of a JSON array to a multivalued field.

   ... | eval json_list = json_array("apple", "banana", "cherry"), mv_field = json_array_to_mv(json_list)

6. json_delete(): Removes one or more keys and their corresponding values from the specified JSON object.

   ... | eval person = json_object("name", "John", "age", 30, "city", "New York"), person_no_age = json_delete(person, "age")

7. json_extend(): Extends the contents of a valid JSON object with the values of an array.

   ... | eval person = json_object("name", "John", "age", 30), extended_person = json_extend(person, json_array("city", "New York"))

8. json_extract(): Returns either a JSON array or a native type value from a field and zero or more paths.

   ... | eval data = json('{"person": {"name": "John", "age": 30}}'), name = json_extract(data, "person.name")

10. json_keys(): Returns the keys from the key-value pairs in a JSON object as a JSON array.

   ... | eval person = json_object("name", "John", "age", 30), keys = json_keys(person)

11. json_set(): Inserts or overwrites values for a JSON node with provided values and returns an updated JSON object.

   ... | eval person = json_object("name", "John"), updated_person = json_set(person, "age", 30)

13. json_valid(): Evaluates whether a JSON object uses valid JSON syntax and returns TRUE or FALSE.

   ... | eval is_valid = json_valid('{"name":"John","age":30}')

14. all(): Iterates over JSON array values and returns true if every value matches the provided predicate.

   ... | eval json_list = json_array(1, 2, 3), all_match = all(json_list, val -> val != 0)

15. any(): Iterates over JSON array values and returns true if any value matches the provided predicate.

   ... | eval json_list = json_array(1, 2, 3), any_match = any(json_list, val -> val == 0)

16. filter(): Iterates over JSON array values and performs an operation on each value.

   ... | eval json_list = json_array(1, 2, 3, 4), filtered_list = filter(json_list, val -> val % 2 == 0)

17. map(): Iterates over JSON array values and performs an operation on each value.

   ... | eval json_list = json_array(1, 2, 3), mapped_list = map(json_list, val -> val * 2)

18. reduce(): Iterates over a JSON array in a field or a literal array and performs an accumulation operation.

   ... | eval json_list = json_array(1, 2, 3), sum = reduce(json_list, 0, (acc, val) -> acc + val)

Technical Considerations

• Consider leveraging existing JSON libraries for efficient parsing and manipulation.
• Ensure that these functions can handle large JSON objects without significant performance degradation.

[A-Gray-Cat]

@YANG-DB These features look awesome. Can we add support to access elements within an array using index too?

[YANG-DB]

@A-Gray-Cat yes that is possible - can you please suggest the syntax and we can discuss it further

[A-Gray-Cat]

Thanks! E.g.

{
    "items": ["a", "b", "c"]
}

Users can access the first element of the array by using syntax like eval first_item = items[0], or it can be retrieved directly using the fields command, e.g. fields items[0].

[A-Gray-Cat]

Hello @YANG-DB , can we also add support to filter a json object using either the key or the value, or both? E.g.

... | eval person = json_object("name", "John", "age", 30), all_match = filter(person, k,v -> k = "name")
... | eval person = json_object("name", "John", "age", 30), all_match = filter(person, k,v -> v = "John")
... | eval person = json_object("name", "John", "age", 30), all_match = filter(person, k,v -> k = "name" and v = "John")