IdentifiableMemoryPersistence<T extends IIdentifiable<K>, K>

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.

public IdentifiableMemoryPersistence(Class type, 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.

public T create(IContext context, T item) throws ApplicationException

• context: IContext - (optional) a context to trace execution through a call chain.
• item: T - item to be created.
• returns: T - created item

deleteById

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

public T deleteById(IContext context, K id) throws ApplicationException

• context: IContext - (optional) a context to trace execution through a call chain.
• id: K - id of the item to be deleted
• returns: T - deleted item.

deleteByIds

Deletes multiple data items based on their unique ids.

public void deleteByIds(context: IContext, ids: K[])

• context: IContext - (optional) a context to trace execution through a call chain.
• ids: K[] - ids of data items to be deleted.

getListByIds

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

public void deleteByIds(IContext context, K[] ids) throws ApplicationException

• context: IContext - (optional) a context to trace execution through a call chain.
• ids: K[] - ids of data items to be retrieved

getOneById

Gets a data item based on its unique id.

public T getOneById(IContext context, K id)

• context: IContext - (optional) a context to trace execution through a call chain.
• id: K - id of data item to be retrieved.
• returns: 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.

public T set(IContext context, T newItem) throws ApplicationException

• context: IContext - (optional) a context to trace execution through a call chain.
• item: T - item to be set.
• returns: T - updated item

update

Updates a data item.

public T update(IContext context, T newItem) throws ApplicationException

• context: IContext - (optional) a context to trace execution through a call chain.
• item: T - item to be updated.
• returns: T - updated item.

updatePartially

Updates only a few selected fields in a data item.

public T updatePartially(IContext context, K id, AnyValueMap data) throws ApplicationException>

• context: IContext - (optional) a context to trace execution through a call chain.
• id: K - id of a data item to be updated.
• data: AnyValueMap - map with fields to be updated.
• returns: T - updated item.

Examples

{@code
  class MyMemoryPersistence extends IdentifiableMemoryPersistence<MyData, String> {
 
    private Predicate<MyData> composeFilter(FilterParams filter) {
        filter = filter != null ? filter : new FilterParams();
        String name = filter.getAsNullableString("name");
        return (item) -> {
            if (name != null && item.name != name)
                return false;
            return true;
        };
    }
 
    public DataPage<MyData> getPageByFilter(IContext context, FilterParams filter, PagingParams paging) {
        super.getPageByFilter(context, this.composeFilter(filter), paging, null, null);
    }
 
  }
 
  MyMemoryPersistence persistence = new MyMemoryPersistence(MyData.class);
 
  MyData item = persistence.create("123", new MyData("1", "ABC"));
  DataPage<MyData> mydata = persistence.getPageByFilter(
          "123",
          FilterParams.fromTuples("name", "ABC"),
          null, null, null);
  System.out.println(mydata.getData().toString());          // Result: { id: "1", name: "ABC" }
  persistence.deleteById("123", "1");
  ...
  }
 

See also

• MemoryPersistence