pip_services3_data.persistence.MemoryPersistence module

pip_services3_data.persistence.MemoryPersistence

Memory persistence implementation

copyright

Conceptual Vision Consulting LLC 2018-2019, see AUTHORS for more details.

license

MIT, see LICENSE for more details.

class pip_services3_data.persistence.MemoryPersistence.MemoryPersistence(loader: pip_services3_data.ILoader.ILoader = None, saver: pip_services3_data.ISaver.ISaver = None)

Bases: pip_services3_commons.config.IConfigurable.IConfigurable, pip_services3_commons.refer.IReferenceable.IReferenceable, pip_services3_commons.run.IOpenable.IOpenable, pip_services3_commons.run.ICleanable.ICleanable

Abstract persistence component that stores data in memory.

This is the most basic persistence component that is only able to store data items of any type. Specific CRUD operations over the data items must be implemented in child classes by accessing self._items() property and calling save() method.

The component supports loading and saving items from another data source. That allows to use it as a base class for file and other types of persistence components that cache all data in memory.

### Configuration parameters ###
  • options:

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

### References ###

  • *:logger:*:*:1.0 (optional) ILogger components to pass log messages

Example:

class MyMemoryPersistence(MemoryPersistence):

    def get_by_name(self, correlationId, name):
        item = self.find(name)
        ...
        return item

persistence = MyMemoryPersistence()

persistence.set("123", MyData("ABC"))
print str(persistence.get_by_name("123", "ABC")))
clear(correlation_id: Optional[str])

Clears component state.

Parameters

correlation_id – (optional) transaction id to trace execution through call chain.

close(correlation_id: Optional[str])

Closes component and frees used resources.

Parameters

correlation_id – (optional) transaction id to trace execution through call chain.

configure(config: pip_services3_commons.config.ConfigParams.ConfigParams)

Configures component by passing configuration parameters.

Parameters

config – configuration parameters to be set.

create(correlation_id: Optional[str], item: T) → T

Creates a data item.

Parameters

  • correlation_id – (optional) transaction id to trace execution through call chain.

  • item – an item to be created.

Returns

a created item

delete_by_filter(correlation_id: Optional[str], filter: Any)

Deletes data items that match to a given filter.

This method shall be called by a public delete_by_filter() method from child class that receives FilterParams and converts them into a filter function.

Parameters

  • correlation_id – (optional) transaction id to trace execution through call chain.

  • filter – (optional) a filter function to filter items.

get_count_by_filter(correlation_id: Optional[str], filter: Any) → int

Gets a number of items retrieved by a given filter.

This method shall be called by a public get_count_by_filter method from child class that receives FilterParams and converts them into a filter function.

Parameters

  • correlation_id – (optional) transaction id to trace execution through call chain.

  • filter – (optional) a filter function to filter items

Returns

a number of data items that satisfy the filter.

get_list_by_filter(correlation_id: Optional[str], filter: Any, sort: Any = None, select: Any = None) → List[T]

Gets a list of data items retrieved by a given filter and sorted according to sort parameters.

This method shall be called by a public get_list_by_filter() method from child class that receives FilterParams and converts them into a filter function.

Parameters

  • correlation_id – (optional) transaction id to trace execution through call chain.

  • filter – (optional) a filter function to filter items

  • sort – (optional) sorting parameters

  • select – (optional) projection parameters (not used yet)

Returns

a data list of results by filter.

get_one_random(correlation_id: Optional[str]) → T

Gets a random item from items that match to a given filter.

This method shall be called by a public get_one_random() method from child class that receives FilterParams and converts them into a filter function.

Parameters

correlation_id – (optional) transaction id to trace execution through call chain.

Returns

a random item.

get_page_by_filter(correlation_id: Optional[str], filter: Any, paging: pip_services3_commons.data.PagingParams.PagingParams, sort: Any = None, select: Any = None) → pip_services3_commons.data.DataPage.DataPage

Gets a page of data items retrieved by a given filter and sorted according to sort parameters.

This method shall be called by a public get_page_by_filter() method from child class that receives FilterParams and converts them into a filter function.

Parameters

  • correlation_id – (optional) transaction id to trace execution through call chain.

  • filter – (optional) a filter function to filter items

  • paging – (optional) paging parameters

  • sort – (optional) sorting parameters

  • select – (optional) projection parameters (not used yet)

Returns

a data page of result by filter.

is_open() → bool

Checks if the component is opened.

Returns

Anyrue if the component has been opened and false otherwise.

load(correlation_id: Optional[str])

TODO add description

open(correlation_id: Optional[str])

Opens the component.

Parameters

correlation_id – (optional) transaction id to trace execution through call chain.

save(correlation_id: Optional[str])

Saves items to external data source using configured saver component.

Parameters

correlation_id – (optional) transaction id to trace execution through call chain.

set_references(references: pip_services3_commons.refer.IReferences.IReferences)

Sets references to dependent components.

Parameters

references – references to locate the component dependencies.