Expand description
Made with Substrate, for DotSama.
§Paged List Pallet
A thin wrapper pallet around a paged_list::StoragePagedList
. It provides an API for a single
paginated list. It can be instantiated multiple times to provide multiple lists.
§Overview
The pallet is quite unique since it does not expose any Call
s, Error
s or Event
s. All
interaction goes through the implemented StorageList
trait.
A fuzzer for testing is provided in crate pallet-paged-list-fuzzer
.
§Examples
- Appending some data to the list can happen either by
Pallet::append_one
:
ⓘ
#[test]
fn append_one_works() {
test_closure(|| {
PagedList::append_one(1);
assert_eq!(PagedList::iter().collect::<Vec<_>>(), vec![1]);
});
}
- or by
Pallet::append_many
. This should always be preferred to repeated calls toPallet::append_one
:
ⓘ
#[test]
fn append_many_works() {
test_closure(|| {
PagedList::append_many(0..3);
assert_eq!(PagedList::iter().collect::<Vec<_>>(), vec![0, 1, 2]);
});
}
- If you want to append many values (ie. in a loop), then best use the
Pallet::appender
:
ⓘ
#[test]
fn appender_works() {
use frame_support::storage::StorageAppender;
test_closure(|| {
let mut appender = PagedList::appender();
appender.append(0);
appender.append(1); // Repeated calls are fine here.
appender.append_many(2..4);
assert_eq!(PagedList::iter().collect::<Vec<_>>(), vec![0, 1, 2, 3]);
});
}
- Iterating over the list can be done with
Pallet::iter
. It uses the standardIterator
trait:
ⓘ
#[test]
fn iter_works() {
test_closure(|| {
PagedList::append_many(0..10);
let mut iter = PagedList::iter();
assert_eq!(iter.next(), Some(0));
assert_eq!(iter.next(), Some(1));
assert_eq!(iter.collect::<Vec<_>>(), (2..10).collect::<Vec<_>>());
});
}
- Draining elements happens through the
Pallet::drain
iterator. Note that even peeking a value will already remove it.
ⓘ
#[test]
fn drain_works() {
test_closure(|| {
PagedList::append_many(0..3);
PagedList::drain().next();
assert_eq!(PagedList::iter().collect::<Vec<_>>(), vec![1, 2], "0 is drained");
PagedList::drain().peekable().peek();
assert_eq!(PagedList::iter().collect::<Vec<_>>(), vec![2], "Peeking removed 1");
});
}
§Pallet API
None. Only things to consider is the Config
traits.
§Low Level / Implementation Details
Implementation details are documented in paged_list::StoragePagedList
.
All storage entries are prefixed with a unique prefix that is generated by ListPrefix
.
Re-exports§
pub use pallet::*;
Modules§
- Helpers for tests.
- The
pallet
module in each FRAME pallet hosts the most important items needed to construct this pallet.
Structs§
- Generates a unique storage prefix for each instance of the pallet.
- A paginated storage list.