IdentifiableMemoryPersistence<T, K>

Inherits: MemoryPersistence, IWriter<T, K>, IGetter<T, K>, 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.

protected 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.

Creates a new instance of the persistence.

public IdentifiableMemoryPersistence()

Instance methods

Create

Creates a data item.

public override Task<T> CreateAsync(string correlationId, T item)

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

DeleteByIdAsync

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

public Task<T> DeleteByIdAsync(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: Task<T> - deleted item.

DeleteByIdsAsync

Deletes multiple data items based on their unique ids.

public Task DeleteByIdAsync(string correlationId, K[] ids)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.
• ids: K[] - ids of data items to be deleted.

GetListByIds

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

public Task<List<T>> GetListByIdsAsync(string correlationId, K[] ids)

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

GetOneById

Gets a data item based on its unique id.

public Task<T> GetOneByIdAsync(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: Task<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 Task<T> SetAsync(string correlationId, T item)

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

Update

Updates a data item.

public Task<T> UpdateAsync(string correlationId, T item)

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

UpdatePartially

Note: this method is not implemented yet.

Updates only a few selected fields in a data item.

public Task<T> UpdatePartially(correlationId: string, id: K, data: AnyValueMap): Task<T>

• 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: Task<T> - updated item.

Examples

class MyMemoryPersistence: IdentifiableMemoryPersistence<MyData, string> 
{
    public MyFilePersistence(string path)
    {
        base(MyData.class, new JsonPersister(path));
        
    private List<Func<MyData, bool>> ComposeFilter(FilterParams filter)
    {
        filter = filter != null ? filter : new FilterParams();
        String name = filter.getAsNullableString("name");
        return List<Func<MyData, bool>>() {
        (item) => {
        if (name != null && item.name != name)
            return false;
        return true;
        }
        };
    }
    
    public DataPage<MyData> GetPageByFilter(string correlationId, FilterParams filter, PagingParams paging)
    {
        base.GetPageByFilter(correlationId, this.composeFilter(filter), paging, null, null);
    }
}
 
var persistence = new MyMemoryPersistence("./data/data.json");
var item = persistence.Create("123", new MyData("1", "ABC"));
var mydata = persistence.GetPageByFilter(
    "123",
    FilterParams.fromTuples("name", "ABC"),
null, null, null);
Console.Out.WriteLine(page.Data);          // Result: { id: "1", name: "ABC" }
persistence.DeleteById("123", "1");
...

See also

• MemoryPersistence