Struct KeySelector

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

A KeySelector identifies a particular key in the database.

FoundationDB’s lexicographically ordered data model permits finding keys based on their order (for example, finding the first key in the database greater than a given key). Key selectors represent a description of a key in the database that could be resolved to an actual key by Transaction::get_key or used directly as the beginning or end of a range in Transaction::getRange.

Note that the way the key selectors are resolved is somewhat non-intuitive, so users who wish to use a key selector other than the default ones described below should probably consult that documentation before proceeding.

Generally one of the following static methods should be used to construct a KeySelector:

• last_less_than
• last_less_or_equal
• first_greater_than
• first_greater_or_equal

Implementations

impl<'a> KeySelector<'a>

pub const fn new(key: Cow<'a, [u8]>, or_equal: bool, offset: i32) -> Self

Constructs a new KeySelector from the given parameters.

pub fn key(&self) -> &[u8]

Returns a the key that serves as the anchor for this KeySelector

pub fn or_equal(&self) -> bool

True if this is an or_equal KeySelector

pub fn offset(&self) -> i32

Returns the key offset parameter for this KeySelector

pub fn last_less_than<K: Into<Cow<'a, [u8]>>>(key: K) -> Self

Creates a KeySelector that picks the last key less than the parameter

pub fn last_less_or_equal<K: Into<Cow<'a, [u8]>>>(key: K) -> Self

Creates a KeySelector that picks the last key less than or equal to the parameter

pub fn first_greater_than<K: Into<Cow<'a, [u8]>>>(key: K) -> Self

Creates a KeySelector that picks the first key greater than the parameter

pub fn first_greater_or_equal<K: Into<Cow<'a, [u8]>>>(key: K) -> Self

Creates a KeySelector that picks the first key greater than or equal to the parameter

Trait Implementations

impl<'a> Clone for KeySelector<'a>

fn clone(&self) -> KeySelector<'a>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Debug for KeySelector<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.