kw_select()

The kw_select function filters rows from a JSON object or array of dictionaries (kw) based on the criteria specified in jn_filter. It returns a new JSON array containing duplicated objects that match the filter. If match_fn is not provided, the default kw_match_simple function is used to evaluate matches.

C

Prototype

PUBLIC json_t *kw_select(
    json_t      *kw,         // not owned
    const char  **keys,
    json_t      *jn_filter,  // owned
    BOOL (*match_fn)(
        json_t *kw,         // not owned
        json_t *jn_filter   // owned
    )
);

Parameters

Parameter	Type	Description
kw	json_t *	The input JSON object or array to filter (not owned).
keys	const char **	A list of keys to include in the returned objects. If NULL, all keys are included.
jn_filter	json_t *	JSON object specifying the filter criteria (owned).
match_fn	BOOL (*)(json_t *, json_t *)	Custom function to evaluate if a row matches the filter criteria. If NULL, the default kw_match_simple function is used.

---

Return Value

• Returns a new JSON array (json_t *) containing duplicated objects that match the filter criteria.

• Returns an empty JSON array if no matches are found or if an error occurs.

Notes

• Ownership:

  • The input parameter kw is not owned and remains unchanged.

  • The jn_filter parameter is owned by the function and will be decremented internally.

  • The returned JSON array is owned by the caller and must be freed when no longer needed.

• Error Handling:

  • Logs an error if kw is not a JSON array or object.

• Duplication:

  • Objects in the result array are duplicated with only the specified keys using kw_duplicate_with_only_keys.

JS

Prototype

// Not applicable in JS

Python

Prototype

# Not applicable in Python

Examples

C

// TODO C examples

JS

// TODO JS examples

Python

# TODO Python examples