Struct Selector 

pub struct Selector<'a> { /* private fields */ }

Represents the state of a JSON Path selection process.

It holds the root JSONB value and the intermediate results (items) found during the execution of a JsonPath.

Implementations

impl<'a> Selector<'a>

pub fn new(root_jsonb: RawJsonb<'a>) -> Self

Creates a new Selector for the given root RawJsonb.

Arguments

• root_jsonb - The RawJsonb data to select from.

pub fn select_values( &mut self, json_path: &'a JsonPath<'a>, ) -> Result<Vec<OwnedJsonb>, Error>

Executes the JsonPath and collects all matching items into a Vec<OwnedJsonb>.

This function returns all matching elements as a Vec<OwnedJsonb>.

Arguments

• self - The JSONPath selector.
• json_path - The JSONPath expression.

Returns

• Ok(Vec<OwnedJsonb>) - A vector containing the selected OwnedJsonb values.
• Err(Error) - If the JSONB data is invalid or if an error occurs during path evaluation.

Examples

use lance_jsonb::jsonpath::parse_json_path;
use lance_jsonb::jsonpath::Selector;
use lance_jsonb::OwnedJsonb;

let jsonb_value = r#"{"a": {"b": [1, 2, 3]}, "c": 4}"#.parse::<OwnedJsonb>().unwrap();
let raw_jsonb = jsonb_value.as_raw();
let mut selector = Selector::new(raw_jsonb);

let path = parse_json_path("$.a.b[*]".as_bytes()).unwrap();
let result = selector.select_values(&path).unwrap();
assert_eq!(result.len(), 3);
assert_eq!(result[0].to_string(), "1");
assert_eq!(result[1].to_string(), "2");
assert_eq!(result[2].to_string(), "3");

See Also

• RawJsonb::select_by_path.

pub fn select_value( &mut self, json_path: &'a JsonPath<'a>, ) -> Result<Option<OwnedJsonb>, Error>

Executes the JsonPath and returns a single value or an array of values.

If exactly one element matches, it is returned directly (wrapped in Some). If multiple elements match, they are returned as a JSON array (wrapped in Some). If no elements match, None is returned.

Arguments

• self - The JSONPath selector.
• json_path - The JSONPath expression.

Returns

• Ok(Some(OwnedJsonb)) - A single OwnedJsonb containing the matched values.
• Ok(None) - The path does not match any values.
• Err(Error) - If the JSONB data is invalid or if an error occurs during path evaluation.

Examples

use lance_jsonb::jsonpath::parse_json_path;
use lance_jsonb::jsonpath::Selector;
use lance_jsonb::OwnedJsonb;

let jsonb_value = r#"{"a": [{"b": 1}, {"b": 2}], "c": 3}"#.parse::<OwnedJsonb>().unwrap();
let raw_jsonb = jsonb_value.as_raw();
let mut selector = Selector::new(raw_jsonb);

let path = parse_json_path("$.c".as_bytes()).unwrap(); // Matches a single value.
let result = selector.select_value(&path).unwrap();
assert_eq!(result.unwrap().to_string(), "3");

let path = parse_json_path("$.a[*].b".as_bytes()).unwrap(); // Matches multiple values.
let result = selector.select_value(&path).unwrap();
assert_eq!(result.unwrap().to_string(), "[1,2]");

let path = parse_json_path("$.x".as_bytes()).unwrap(); // No match.
let result = selector.select_value(&path).unwrap();
assert!(result.is_none());

See Also

• RawJsonb::select_value_by_path.

pub fn exists(&mut self, json_path: &'a JsonPath<'a>) -> Result<bool, Error>

Executes the JsonPath and checks if any item matches.

Arguments

• self - The JSONPath selector.
• json_path - The JSONPath expression.

Returns

• Ok(true) - If the JSON path exists.
• Ok(false) - If the JSON path does not exist.
• Err(Error) - If the JSONB data is invalid or if an error occurs during path evaluation. This could also indicate issues with the json_path itself.

Examples

use lance_jsonb::jsonpath::parse_json_path;
use lance_jsonb::jsonpath::Selector;
use lance_jsonb::OwnedJsonb;

let jsonb_value = r#"{"a": {"b": [1, 2, 3]}, "c": 4}"#.parse::<OwnedJsonb>().unwrap();
let raw_jsonb = jsonb_value.as_raw();
let mut selector = Selector::new(raw_jsonb);

// Valid paths
let path1 = parse_json_path("$.a.b[1]".as_bytes()).unwrap();
assert!(selector.exists(&path1).unwrap());

let path2 = parse_json_path("$.c".as_bytes()).unwrap();
assert!(selector.exists(&path2).unwrap());

// Invalid paths
let path3 = parse_json_path("$.a.x".as_bytes()).unwrap(); // "x" does not exist
assert!(!selector.exists(&path3).unwrap());

See Also

• RawJsonb::path_exists.