Struct near_sdk::collections::LookupMap

pub struct LookupMap<K, V> { /* private fields */ }

An non-iterable implementation of a map that stores its content directly on the trie.

Implementations

impl<K, V> LookupMap<K, V>

pub fn new<S>(key_prefix: S) -> Self where
    S: IntoStorageKey, 

Create a new map. Use key_prefix as a unique prefix for keys.

Examples

use near_sdk::collections::LookupMap;
let mut map: LookupMap<String, String> = LookupMap::new(b"m");

pub fn insert_raw(&mut self, key_raw: &[u8], value_raw: &[u8]) -> Option<Vec<u8>>

Inserts a serialized key-value pair into the map. If the map did not have this key present, None is returned. Otherwise returns a serialized value. Note, the keys that have the same hash value are undistinguished by the implementation.

pub fn remove_raw(&mut self, key_raw: &[u8]) -> Option<Vec<u8>>

Removes a serialized key from the map, returning the serialized value at the key if the key was previously in the map.

impl<K, V> LookupMap<K, V> where
    K: BorshSerialize,
    V: BorshSerialize + BorshDeserialize, 

pub fn contains_key(&self, key: &K) -> bool

Returns true if the map contains a given key.

Examples

use near_sdk::collections::LookupMap;

let mut map: LookupMap<String, String> = LookupMap::new(b"m");
assert_eq!(map.contains_key(&"Toyota".into()), false);

map.insert(&"Toyota".into(), &"Camry".into());
assert_eq!(map.contains_key(&"Toyota".into()), true);

pub fn get(&self, key: &K) -> Option<V>

Returns the value corresponding to the key.

Examples

use near_sdk::collections::LookupMap;

let mut map: LookupMap<String, String> = LookupMap::new(b"m");
assert_eq!(map.get(&"Toyota".into()), None);

map.insert(&"Toyota".into(), &"Camry".into());
assert_eq!(map.get(&"Toyota".into()), Some("Camry".into()));

pub fn remove(&mut self, key: &K) -> Option<V>

Removes a key from the map, returning the value at the key if the key was previously in the map.

Examples

use near_sdk::collections::LookupMap;

let mut map: LookupMap<String, String> = LookupMap::new(b"m");
assert_eq!(map.remove(&"Toyota".into()), None);

map.insert(&"Toyota".into(), &"Camry".into());
assert_eq!(map.remove(&"Toyota".into()), Some("Camry".into()));

pub fn insert(&mut self, key: &K, value: &V) -> Option<V>

Inserts a key-value pair into the map. If the map did not have this key present, None is returned. Otherwise returns a value. Note, the keys that have the same hash value are undistinguished by the implementation.

Examples

use near_sdk::collections::LookupMap;

let mut map: LookupMap<String, String> = LookupMap::new(b"m");
assert_eq!(map.insert(&"Toyota".into(), &"Camry".into()), None);
assert_eq!(map.insert(&"Toyota".into(), &"Corolla".into()), Some("Camry".into()));

pub fn extend<IT: IntoIterator<Item = (K, V)>>(&mut self, iter: IT)

Inserts all new key-values from the iterator and replaces values with existing keys with new values returned from the iterator.

Examples

use near_sdk::collections::LookupMap;

let mut extendee: LookupMap<String, String> = LookupMap::new(b"m");
let mut source = vec![];

source.push(("Toyota".into(), "Camry".into()));
source.push(("Nissan".into(), "Almera".into()));
source.push(("Ford".into(), "Mustang".into()));
source.push(("Chevrolet".into(), "Camaro".into()));
extendee.extend(source.into_iter());

Trait Implementations

impl<K, V> BorshDeserialize for LookupMap<K, V> where
    Vec<u8>: BorshDeserialize, 

fn deserialize(buf: &mut &[u8]) -> Result<Self, Error>

Deserializes this instance from a given slice of bytes. Updates the buffer to point at the remaining bytes.

fn try_from_slice(v: &[u8]) -> Result<Self, Error>

Deserialize this instance from a slice of bytes.

impl<K, V> BorshSerialize for LookupMap<K, V> where
    Vec<u8>: BorshSerialize, 

fn serialize<W: Write>(&self, writer: &mut W) -> Result<(), Error>

fn try_to_vec(&self) -> Result<Vec<u8, Global>, Error>

Serialize this instance into a vector of bytes.

impl<K, V> Debug for LookupMap<K, V> where
    K: Debug + BorshSerialize,
    V: Debug + BorshSerialize + BorshDeserialize, 

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

Formats the value using the given formatter.