Table
The Table provides a flexible and efficient way to manage large amounts of data in a table format. Each table item is represented as a separate global state item, allowing for scalable storage solutions.
Core Features of Table
Structure
The Table struct is designed to handle large-scale storage with efficiency:
handle: An address that uniquely identifies the table.
Constants
The following constants define various error codes used within the module (these are implied but not explicitly stated in the provided code):
ENOT_FOUND: Key not found in the table.EALREADY_EXIST: Key already exists in the table.EINVALID_ARGUMENT: Invalid argument passed to a function.
API Overview
Creating Tables
new<K: copy + drop, V: store>(): Table<K, V>: Creates a new table.
Managing Entries
add<K: copy + drop, V>(table: &mut Table<K, V>, key: K, val: V): Adds a key-value pair to the table. Aborts if the key already exists.remove<K: copy + drop, V>(table: &mut Table<K, V>, key: K): V: Removes and returns the value associated with a key. Aborts if the key is not found.upsert<K: copy + drop, V: drop>(table: &mut Table<K, V>, key: K, value: V): Inserts or updates a key-value pair.
Retrieving Entries
borrow<K: copy + drop, V>(table: &Table<K, V>, key: K): &V: Returns an immutable reference to the value associated with a key. Aborts if the key is not found.borrow_with_default<K: copy + drop, V>(table: &Table<K, V>, key: K, default: &V): &V: Returns the value associated with a key or a default value if the key is not found.borrow_mut<K: copy + drop, V>(table: &mut Table<K, V>, key: K): &mut V: Returns a mutable reference to the value associated with a key. Aborts if the key is not found.borrow_mut_with_default<K: copy + drop, V: drop>(table: &mut Table<K, V>, key: K, default: V): &mut V: Inserts a key-value pair if the key is not found, then returns a mutable reference to the value.
Utility Functions
contains<K: copy + drop, V>(table: &Table<K, V>, key: K): bool: Checks if the table contains a key.
Example Usage
Creating and Using a Table
table.move
module 0x42::table_usage {
use aptos_std::table;
public entry fun main() {
let table = table::new<u64, u64>();
table::add(&mut table, 1, 100);
table::add(&mut table, 2, 200);
let value1 = table::borrow(&table, 1);
assert!(*value1 == 100, 0);
let value2 = table::borrow(&table, 2);
assert!(*value2 == 200, 0);
let removed_value = table::remove(&mut table, 1);
assert!(removed_value == 100, 0);
let contains_key = table::contains(&table, 2);
assert!(contains_key, 0);
// Note: A table must be stored in a resource at the end of a function
}
}Adding and Upserting Multiple Entries
table.move
module 0x42::table_usage {
use aptos_std::table;
public fun add_and_upsert_entries() {
let table = table::new<u64, u64>();
table::add(&mut table, 1, 100);
table::upsert(&mut table, 1, 200);
table::upsert(&mut table, 2, 300);
let value1 = table::borrow(&table, 1);
assert!(*value1 == 200, 0);
let value2 = table::borrow(&table, 2);
assert!(*value2 == 300, 0);
// Note: A table must be stored in a resource at the end of a function
}
}Borrowing Mutable References
table.move
module 0x42::table_usage {
use aptos_std::table;
public fun borrow_mutable_references() {
let table = table::new<u64, u64>();
table::add(&mut table, 1, 100);
let value_mut = table::borrow_mut(&mut table, 1);
*value_mut = 200;
let value = table::borrow(&table, 1);
assert!(*value == 200, 0);
// Note: A table must be stored in a resource at the end of a function
}
}