IdentifiableMemoryPersistence<T extends IIdentifiable<K>, K>

Abstract persistence component that stores data in memory and implements a number of CRUD operations over data items with unique ids.

Extends: MemoryPersistence

Implements: IWriter, IGetter, ISetter

Description

The IdentifiableMemoryPersistence class allows you to create persistence components that store data in memory and implement a number of CRUD operations over data items with unique ids.

Important points

  • The data items must implement IIdentifiable.
  • In basic scenarios child classes shall only override getPageByFilter, getListByFilter or deleteByFilter operations with a specific filter function. All other operations can be used out of the box.
  • In complex scenarios child classes can implement additional operations by accessing cached items via the this._items property and calling the save method on updates.

Configuration parameters

options:

  • max_page_size: maximum number of items returned in a single page (default: 100)

References

  • *:logger:*:*:1.0 - (optional) (../../../components/log/ilogger) components to pass log messages

Constructors

Creates a new instance of the identifiable file persistence component.

IdentifiableMemoryPersistence([ILoader loader, ISaver saver])

  • loader: ILoader - (optional) loader used to load items from an external datasource.
  • saver: ISaver - (optional) saver used to save items to and external datasource.

Instance methods

create

Creates a data item.

@override

Future<T?> create(String? correlationId, T? item)

  • correlationId: String? - (optional) transaction id used to trace execution through the call chain.
  • item: T? - item to be created.
  • returns: Future<T?> - created item

deleteById

Deletes a data item based on it’s unique id.

@override

Future<T?> deleteById(String? correlationId, K? id)

  • correlationId: String? - (optional) transaction id used to trace execution through the call chain.
  • id: K? - id of the item to be deleted
  • returns: Future<T?> - deleted item.

deleteByIds

Deletes multiple data items based on their unique ids.

Future deleteByIds(String? correlationId, List<K> ids)

  • correlationId: String? - (optional) transaction id used to trace execution through the call chain.
  • ids: List<K> - ids of data items to be deleted.

getListByIds

Gets a list of data items retrieved by given unique ids.

Future<List<T>> getListByIds(String? correlationId, List<K> ids)

  • correlationId: String? - (optional) transaction id used to trace execution through the call chain.
  • ids: List<K> - ids of data items to be retrieved
  • returns: Future<List<T>> - data list of results by ids.

getOneById

Gets a data item based on its unique id.

@override

Future<T> getOneById(String? correlationId, K id)

  • correlationId: String? - (optional) transaction id used to trace execution through the call chain.
  • id: K - id of data item to be retrieved.
  • returns: Future<T> - data item by id.

set

Sets a data item. If the data item exists, it updates it. Otherwise, it creates a new data item.

Future<T> set(String? correlationId, T item)

  • correlationId: String? - (optional) transaction id used to trace execution through the call chain.
  • item: T - item to be set.
  • returns: Future<T> - updated item

update

Updates a data item.

@override

Future<T> update(String? correlationId, T item)

  • correlationId: String? - (optional) transaction id used to trace execution through the call chain.
  • item: T - item to be updated.
  • returns: Future<T> - updated item.

updatePartially

Updates only a few selected fields in a data item.

Future<T> updatePartially(String? correlationId, K id, AnyValueMap data)

  • correlationId: String? - (optional) transaction id used to trace execution through the call chain.
  • id: K - id of a data item to be updated.
  • data: AnyValueMap - map with fields to be updated.
  • returns: Future<T> - updated item.

Examples

     class MyMemoryPersistence extends IdentifiableMemoryPersistence<MyData, string> {

         dynamic _composeFilter(FilterParams filter) {
             filter = filter ?? FilterParams();
             var name = filter.getAsNullableString("name");
             return (item) {
                 if (name != null && item.name != name)
                     return false;
                 return true;
             };
         }

         Future<DataPage<MyData>> getPageByFilter(String? correlationId, FilterParams filter, PagingParams paging){
             return super.getPageByFilter(correlationId, composeFilter(filter), paging, null, null);
         }

     }

    var persistence = MyMemoryPersistence();

    var item = persistence.create("123", { id: "1", name: "ABC" })
    var page = persistence.getPageByFilter(
             "123",
             FilterParams.fromTuples(["name", "ABC"]),
             null);

    print(page.data);          // Result: { id: "1", name: "ABC" }

    item = persistence.deleteById("123", "1");
                     ...

See also