ButlerAttributeManager¶
-
class
lsst.daf.butler.registry.interfaces.
ButlerAttributeManager
¶ Bases:
lsst.daf.butler.registry.interfaces.VersionedExtension
An interface for managing butler attributes in a
Registry
.Attributes are represented in registry as a set of name-value pairs, both have string type. Any non-string data types (e.g. integers) need to be converted to/from strings on client side. Attribute names can be arbitrary strings, no particular structure is enforced by this interface. Attribute names are globally unique, to avoid potential collision clients should follow some common convention for attribute names, e.g. dot-separated components (
config.managers.opaque
).One of the critical pieces of information that will be stored as attribute is the version of database schema which needs to be known before registry can do any operations on database. For that reasons it is likely there will be only one implementation of this interface which uses database table with a stable schema.
Methods Summary
currentVersion
()Return extension version as defined by current implementation. delete
(name)Delete an attribute. empty
()Check whether attributes set is empty. extensionName
()Return full name of the extension. get
(name, default)Retrieve value of a given attribute. initialize
(db, context)Construct an instance of the manager. items
()Iterate over attributes and yield their names and values. schemaDigest
()Return digest for schema piece managed by this extension. set
(name, value, *, force)Set value for a given attribute. Methods Documentation
-
classmethod
currentVersion
() → Optional[lsst.daf.butler.registry.interfaces._versioning.VersionTuple]¶ Return extension version as defined by current implementation.
This method can return
None
if an extension does not require its version to be saved or checked.Returns: - version :
VersionTuple
Current extension version or
None
.
- version :
-
delete
(name: str) → bool¶ Delete an attribute.
Parameters: - name :
str
Attribute name, arbitrary non-empty string.
Returns: - name :
-
empty
() → bool¶ Check whether attributes set is empty.
Returns: - empty :
bool
True if there are no any attributes defined.
- empty :
-
classmethod
extensionName
() → str¶ Return full name of the extension.
This name should match the name defined in registry configuration. It is also stored in registry attributes. Default implementation returns full class name.
Returns: - name :
str
Full extension name.
- name :
-
get
(name: str, default: Optional[str] = None) → Optional[str]¶ Retrieve value of a given attribute.
Parameters: Returns: - value :
str
Attribute value, if attribute does not exist then
default
is returned.
- value :
-
classmethod
initialize
(db: Database, context: StaticTablesContext) → ButlerAttributeManager¶ Construct an instance of the manager.
Parameters: - db :
Database
Interface to the underlying database engine and namespace.
- context :
StaticTablesContext
Context object obtained from
Database.declareStaticTables
; used to declare any tables that should always be present in a layer implemented with this manager.
Returns: - manager :
ButlerAttributeManager
An instance of
ButlerAttributeManager
.
- db :
-
items
() → Iterable[Tuple[str, str]]¶ Iterate over attributes and yield their names and values.
Yields:
-
schemaDigest
() → Optional[str]¶ Return digest for schema piece managed by this extension.
Returns: Notes
There is no exact definition of digest format, any string should work. The only requirement for string contents is that it has to remain stable over time if schema does not change but it should produce different string for any change in the schema. In many cases default implementation in
_defaultSchemaDigest
can be used as a reasonable choice.
-
set
(name: str, value: str, *, force: bool = False) → None¶ Set value for a given attribute.
Parameters: - name :
str
Attribute name, arbitrary non-empty string.
- value :
str
New value for an attribute, 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 attributes. With default
False
value an exception is raised if attributename
already exists, ifTrue
is passed then value of the existing attribute will be updated.
Raises: - ButlerAttributeExistsError
Raised if attribute already exists but
force
option is false.- ValueError
Raised if name or value parameters are empty.
- name :
-
classmethod