DeferredDatasetHandle

class lsst.daf.butler.DeferredDatasetHandle(butler: LimitedButler, ref: DatasetRef, parameters: dict | None, storageClass: str | StorageClass | None = None)

Bases: object

Proxy class that provides deferred loading of datasets from a butler.

Attributes Summary

dataId

The full data ID associated with the dataset (DataCoordinate).

storageClass

Optional storage class override that can be applied on get().

Methods Summary

get(*[, component, parameters, storageClass])

Retrieves the dataset pointed to by this handle

Attributes Documentation

dataId

The full data ID associated with the dataset (DataCoordinate).

Guaranteed to contain records.

storageClass: str | StorageClass | None = None

Optional storage class override that can be applied on get().

Methods Documentation

get(*, component: str | None = None, parameters: dict | None = None, storageClass: str | StorageClass | None = None, **kwargs: dict) → Any

Retrieves the dataset pointed to by this handle

This handle may be used multiple times, possibly with different parameters.

Parameters:
componentstr or None

If the deferred object is a component dataset type, this parameter may specify the name of the component to use in the get operation.

parametersdict or None

The parameters argument will be passed to the butler get method. It defaults to None. If the value is not None, this dict will be merged with the parameters dict used to construct the DeferredDatasetHandle class.

storageClassStorageClass or str, optional

The storage class to be used to override the Python type returned by this method. By default the returned type matches the dataset type definition for this dataset or the storage class specified when this object was created. Specifying a read StorageClass can force a different type to be returned. This type must be compatible with the original type.

**kwargs

This argument is deprecated and only exists to support legacy gen2 butler code during migration. It is completely ignored and will be removed in the future.

Returns:
returnObject

The dataset pointed to by this handle