feat: Function to mimick Postgres json_extract_path_text #73
Description
In Postgres, json_extract_path_text will return a string value without the surrounding double quotes, and any other values as casted strings. Paths not found become NULL's.
https://www.postgresql.org/docs/9.3/functions-json.html
I tried using json_as_text but it fails on cases where the path is not found.
Locally I have vendored the JsonPath and created this function which is giving me the expected behavior.
If there is no way of getting this desired behavior with the existing tools, I could publish my UDF. It's marginally redundant behavior, so I wonder if theres an easier way to factor things.
/// This function mimics the behavior of PostgreSQL's `json_extract_path_text`,
/// which returns the value at a given JSON path as text or NULL if not found.
/// Non-string values are returned as their JSON representation.
fn jiter_json_extract_path_text(
opt_json: Option<&str>,
path: &[JsonPath],
) -> Result<Option<String>, jiter::JiterError> {
if let Some((mut jiter, peek)) = jiter_json_find(opt_json, path) {
match peek {
Peek::Null => {
jiter.known_null()?;
// The value is JSON null; Postgres returns SQL NULL in this case
Ok(None)
}
Peek::String => {
let s = jiter.known_str()?;
Ok(Some(s.to_owned()))
}
_ => {
// For other types (number, bool, object, array), we return their textual representation.
let start = jiter.current_index();
jiter.known_skip(peek)?;
let slice = jiter.slice_to_current(start);
match String::from_utf8(slice.to_vec()) {
Ok(val_str) => Ok(Some(val_str)),
Err(_) => Ok(None),
}
}
}
} else {
// Path not found; return NULL
Ok(None)
}
}Side note: Could JsonPath be published with the crate in a common package?