lsst.dax.apdb.apdbMetadata.ApdbMetadata Class Reference

Inheritance diagram for lsst.dax.apdb.apdbMetadata.ApdbMetadata:

Public Member Functions
str|None	get (self, str key, str|None default=None)
None	set (self, str key, str value, *, bool force=False)
bool	delete (self, str key)
Generator[tuple[str, str], None, None]	items (self)
bool	empty (self)

Detailed Description

Interface for accessing APDB metadata.

Metadata is a collection of key/value items usually stored in a special
table in the database. This abstract interface provides methods for
accessing and modifying it.

Member Function Documentation

delete()

bool lsst.dax.apdb.apdbMetadata.ApdbMetadata.delete	(		self,
		str	key )

Delete metadata record.

Parameters
----------
key : `str`
    Metadata key, arbitrary non-empty string.

Returns
-------
existed : `bool`
    `True` is returned if attribute existed before it was deleted.

Reimplemented in lsst.dax.apdb.cassandra.apdbMetadataCassandra.ApdbMetadataCassandra, and lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.

empty()

bool lsst.dax.apdb.apdbMetadata.ApdbMetadata.empty

(

self

)

Check whether attributes set is empty.

Returns
-------
empty : `bool`
    `True` if there are no any attributes defined. `True` is also
    returned if metadata table is missing.

Reimplemented in lsst.dax.apdb.cassandra.apdbMetadataCassandra.ApdbMetadataCassandra, and lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.

get()

str | None lsst.dax.apdb.apdbMetadata.ApdbMetadata.get	(		self,
		str	key,
		str | None	default = None )

Retrieve value of a given metadata record.

Parameters
----------
key : `str`
    Metadata key, arbitrary non-empty string.
default : `str`, optional
    Default value returned when key does not exist, can be string
    or `None`.

Returns
-------
value : `str` or `None`
    Metadata value, if key does not exist then ``default`` is returned.

Reimplemented in lsst.dax.apdb.cassandra.apdbMetadataCassandra.ApdbMetadataCassandra, and lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.

items()

Generator[tuple[str, str], None, None] lsst.dax.apdb.apdbMetadata.ApdbMetadata.items

(

self

)

Iterate over records and yield their keys and values.

Yields
------
key : `str`
    Metadata key.
value : `str`
    Corresponding metadata value.

Reimplemented in lsst.dax.apdb.cassandra.apdbMetadataCassandra.ApdbMetadataCassandra, and lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.

set()

None lsst.dax.apdb.apdbMetadata.ApdbMetadata.set	(		self,
		str	key,
		str	value,
		*	,
		bool	force = False )

Set value for a given metadata record.

Parameters
----------
key : `str`
    Metadata key, arbitrary non-empty string.
value : `str`
    New metadata value, an arbitrary string. Due to deficiencies of
    some database engines we are not allowing empty strings to be
    stored in the database, and ``value`` cannot be an empty string.
force : `bool`, optional
    Controls handling of existing metadata. With default `False`
    value an exception is raised if ``key`` already exists, if `True`
    is passed then value of the existing key will be updated.

Raises
------
KeyError
    Raised if key already exists but ``force`` option is false.
ValueError
    Raised if key or value parameters are empty.

Reimplemented in lsst.dax.apdb.cassandra.apdbMetadataCassandra.ApdbMetadataCassandra, and lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.

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The documentation for this class was generated from the following file:

• python/lsst/dax/apdb/apdbMetadata.py