IdentifiableFilePersistence<T extends IIdentifiable<K>, K>

Extends: IdentifiableMemoryPersistence<T, K>

Description

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

Important points

• The data items must implement the IIdentifiable interface.
• 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 self._items property and calling the save method on updates.

Configuration parameters

• path: path to the file where data is stored

• 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 persistence.

IdentifiableFilePersistence([JsonFilePersister persister])

• persister: JsonFilePersister - (optional) persister component that loads and saves data from/to flat file.

Fields

Instance methods

configure

Configures a component by passing its configuration parameters.

@override

void configure(ConfigParams config)

• config: ConfigParams - configuration parameters to be set.

Examples

class MyFilePersistence extends IdentifiableFilePersistence<MyData, String> {
    MyFilePersistence([String path]):super(JsonPersister(path)) {
    }
    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 = MyFilePersistence("./data/data.json");
await persistence.create("123", { id: "1", name: "ABC" });
var page = await persistence.getPageByFilter(
        "123",
        FilterParams.fromTuples([
            "name", "ABC"
        ]),
        null);

print(page.data);          // Result: { id: "1", name: "ABC" }
var item = await persistence.deleteById("123", "1");

See also

• MemoryPersistence