Background

While fixing a bug in projectdiscovery/naabu (see projectdiscovery/naabu#1545), we identified a limitation in the current structs.FilterStruct utility.
It sets excluded fields to their Go zero-value. When marshaled to JSON, not all zero-values are omitted (e.g., time.Time, fields without omitempty), which leads to unexpected fields being included.

Proposal

To solve this problem generically, we propose adding a new utility function, FilterStructToMap.

This function would have a similar signature to FilterStruct but would return a map[string]any instead of the original struct type T. Its responsibilities would be:

1. Filter fields based on include/exclude lists.
2. Use the json tag as the key for the resulting map.
3. Correctly handle the omitempty tag by not adding zero-valued fields to the map.

This provides a clean and reusable way to convert a struct into a filtered map, making it well-suited for preparing data for JSON marshaling. Beyond addressing the immediate need in naabu, it can also be applied across other ProjectDiscovery tools that face similar output-filtering challenges.