Big_map

A lazily deserialised map that is intended to store large amounts of data. Here, "lazily" means that storage is read or written per key on demand. Therefore there are no map, fold, and iter operations as there are in Map.

Compared to strict maps, which have a high upfront gas cost to deserialise all the data and then have cheaper access costs thereafter, lazily deserialised maps spread this cost out across each access, increasing the per-access gas costs, but providing a cheaper overall cost when only a small portion of a large dataset is needed.

cameligo

val empty : ('key, 'value) big_map

jsligo

let empty: big_map<'key, 'value>

Create an empty big map.

type move = [int, int];
type register = big_map<address, move>;

let empty: register = Big_map.empty;

cameligo

val literal : ('key * 'value) list -> ('key, 'value) big_map

jsligo

let literal: (items: list<['key, 'value]>) => big_map<'key, 'value>

Create a non-empty big_map.

let moves: register =
  Big_map.literal (list([
    [("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" as address), [1, 2]],
    [("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" as address), [0, 3]]]));

cameligo

val find_opt : 'key -> ('key, 'value) big_map -> 'value option

jsligo

let find_opt: (key: 'key, big_map: big_map <'key, 'value>) => option <'value>

Retrieve a value from a big map with the given key.

Because the key may be missing in the big map, the result is an optional value.

let my_balance: option <move> =
  Big_map.find_opt(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" as address), moves);

cameligo

val mem : 'key -> ('key, 'value) big_map -> bool

jsligo

let mem: (key: 'key, big_map: big_map <'key, 'value>) => bool

Test whether a given key exists within a big map.

let has_balance: bool =
  Big_map.mem(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" as address), moves);

cameligo

val update: 'key -> 'value option -> ('key, 'value) big_map -> ('key, 'value) big_map

jsligo

let update: (key: 'key, value: option<'value>, big_map: big_map<'key, 'value>) => big_map<'key, 'value>

Note: when None is used as a value, the value is removed from the big_map.

let updated_map: register =
  Big_map.update
    (("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" as address), Some([4,9]), moves);

cameligo

val get_and_update : 'key -> 'value option -> ('key, 'value) big_map -> value option * ('key, 'value) big_map

jsligo

let get_and_update: (key: 'key, value: option<'value>, big_map: big_map<'key, 'value>) => [option<'value>, big_map<'key, 'value>]

Similar to update but it also returns the value that was previously stored in the big_map

cameligo

val add : 'key -> 'value -> ('key, 'value) big_map  -> ('key, 'value) big_map

jsligo

let add: (key: 'key, value: 'value, big_map: big_map<'key, 'value>) => big_map<'key, 'value>

let add = (m: register): register =>
  Big_map.add
    (("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" as address), [4,9], m);

cameligo

val remove: 'key -> ('key, 'value) big_map -> ('key, 'value) big_map

jsligo

let remove: (key: 'key, big_map: big_map<'key, 'value>) => big_map<'key, 'value>

let updated_map_: register =
  Big_map.remove(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" as address), moves);