# LocalFileStorage

class `openff.evaluator.storage.``LocalFileStorage`(root_directory='stored_data')

  A storage backend which stores files in directories on the local disk.

  `__init__`(root_directory='stored_data')

    Constructs a new StorageBackend object.

  Methods

  `__init__`([root_directory]) | Constructs a new StorageBackend object.
  `has_force_field`(force_field) | A convenience method for checking whether the specified ForceFieldSource object is stored in the backend.
  `has_object`(storage_object) | Checks whether a given hashable object exists in the storage system.
  `query`(data_query) | Query the storage backend for data matching the query criteria.
  `retrieve_force_field`(storage_key) | A convenience method for retrieving ForceFieldSource objects.
  `retrieve_object`(storage_key[, expected_type]) | Retrieves a stored object for the estimators storage system.
  `store_force_field`(force_field) | A convenience method for storing ForceFieldSource objects.
  `store_object`(object_to_store[, …]) | Store an object in the storage system, returning the key of the stored object.

  Attributes

  `root_directory` | Returns the directory in which all stored objects are located.

  property `root_directory`

    Returns the directory in which all stored objects are located.

    Type

      str

  `has_force_field`(force_field)

    A convenience method for checking whether the specified ForceFieldSource object is stored in the backend.

    Parameters

      force_field (ForceFieldSource) – The force field to look for.

    Returns

      The unique key of the object if it is in the system, None otherwise.

    Return type

      str, optional

  `has_object`(storage_object)

    Checks whether a given hashable object exists in the storage system.

    Parameters

      storage_object (BaseStoredData) – The object to check for.

    Returns

      The unique key of the object if it is in the system, None otherwise.

    Return type

      str, optional

  `query`(data_query)

    Query the storage backend for data matching the query criteria.

    Parameters

      data_query (BaseDataQuery) – The query to perform.

    Returns

      The data that matches the query partitioned by the matched values. The list values take the form (storage_key, data_object, data_directory_path).

    Return type

      dict of tuple and list of tuple of str, BaseStoredData and str

  `retrieve_force_field`(storage_key)

    A convenience method for retrieving ForceFieldSource objects.

    Parameters

      storage_key (str) – The key of the force field to retrieve.

    Returns

      The retrieved force field source.

    Return type

      ForceFieldSource

  `retrieve_object`(storage_key, expected_type=None)

    Retrieves a stored object for the estimators storage system.

    Parameters

      - storage_key (str) – A unique key that describes where the stored object can be found within the storage system.

      - expected_type (type of BaseStoredData, optional) – The expected data type. An exception is raised if the retrieved data doesn’t match the type.

    Returns

      - BaseStoredData, optional – The stored object if the object key is found, otherwise None.

      - str, optional – The path to the ancillary data if present.

  `store_force_field`(force_field)

    A convenience method for storing ForceFieldSource objects.

    Parameters

      force_field (ForceFieldSource) – The force field to store.

    Returns

      The unique id of the stored force field.

    Return type

      str

  `store_object`(object_to_store, ancillary_data_path=None)

    Store an object in the storage system, returning the key of the stored object. This may be different to storage_key depending on whether the same or a similar object was already present in the system.

    Parameters

      - object_to_store (BaseStoredData) – The object to store.

      - ancillary_data_path (str , optional) – The data path to the ancillary directory-like data to store alongside the object if the data type requires one.

    Returns

      The unique key assigned to the stored object.

    Return type

      str