Inheritance diagram for lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql:
Public Member Functions | |
| __init__ (self, sqlalchemy.engine.Engine engine, sqlalchemy.schema.Table|None table) | |
| 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) |
| bool | table_exists (self) |
Protected Attributes | |
| _engine | |
| _table | |
Detailed Description
Implementation of `ApdbMetadata` for SQL backend.
Parameters
----------
engine : `sqlalchemy.engine.Engine`
Database access engine.
table : `sqlalchemy.schema.Table` or `None`
Database table holding metadata. If table does not exists then `None`
should be specified.
Definition at line 33 of file apdbMetadataSql.py.
Constructor & Destructor Documentation
◆ __init__()
| lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.__init__ | ( | self, | |
| sqlalchemy.engine.Engine | engine, | ||
| sqlalchemy.schema.Table | None | table ) |
Definition at line 45 of file apdbMetadataSql.py.
45 def __init__(self, engine: sqlalchemy.engine.Engine, table: sqlalchemy.schema.Table | None):
46 self._engine = engine
47 self._table = table
48
Member Function Documentation
◆ delete()
| bool lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.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 from lsst.dax.apdb.apdbMetadata.ApdbMetadata.
Definition at line 83 of file apdbMetadataSql.py.
83 def delete(self, key: str) -> bool:
84 # Docstring is inherited.
85 if self._table is None:
86 # Missing table means nothing to delete.
87 return False
88 stmt = sqlalchemy.sql.delete(self._table).where(self._table.columns.name == key)
89 with self._engine.begin() as conn:
90 result = conn.execute(stmt)
91 return result.rowcount > 0
92
◆ empty()
| bool lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.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 from lsst.dax.apdb.apdbMetadata.ApdbMetadata.
Definition at line 104 of file apdbMetadataSql.py.
104 def empty(self) -> bool:
105 # Docstring is inherited.
106 if self._table is None:
107 # Missing table means empty.
108 return True
109 stmt = sqlalchemy.sql.select(sqlalchemy.sql.func.count()).select_from(self._table)
110 with self._engine.begin() as conn:
111 result = conn.execute(stmt)
112 count = result.scalar()
113 return count == 0
114
◆ get()
| str | None lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.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 from lsst.dax.apdb.apdbMetadata.ApdbMetadata.
Definition at line 49 of file apdbMetadataSql.py.
49 def get(self, key: str, default: str | None = None) -> str | None:
50 # Docstring is inherited.
51 if self._table is None:
52 return default
53 sql = sqlalchemy.sql.select(self._table.columns.value).where(self._table.columns.name == key)
54 with self._engine.begin() as conn:
55 result = conn.execute(sql)
56 value = result.scalar()
57 if value is not None:
58 return value
59 return default
60
◆ items()
| Generator[tuple[str, str], None, None] lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.items | ( | self | ) |
Iterate over records and yield their keys and values.
Yields
------
key : `str`
Metadata key.
value : `str`
Corresponding metadata value.
Reimplemented from lsst.dax.apdb.apdbMetadata.ApdbMetadata.
Definition at line 93 of file apdbMetadataSql.py.
94 # Docstring is inherited.
95 if self._table is None:
96 # Missing table means nothing to return.
97 return
98 stmt = sqlalchemy.sql.select(self._table.columns.name, self._table.columns.value)
99 with self._engine.begin() as conn:
100 result = conn.execute(stmt)
101 for row in result:
102 yield row._tuple()
103
◆ set()
| None lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.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 from lsst.dax.apdb.apdbMetadata.ApdbMetadata.
Definition at line 61 of file apdbMetadataSql.py.
62 # Docstring is inherited.
63 if self._table is None:
64 raise RuntimeError("Metadata table does not exist")
65 if not key or not value:
66 raise ValueError("name and value cannot be empty")
67 try:
68 insert = sqlalchemy.sql.insert(self._table).values(name=key, value=value)
69 with self._engine.begin() as conn:
70 conn.execute(insert)
71 except sqlalchemy.exc.IntegrityError as exc:
72 # Try to update if it exists.
73 if not force:
74 raise KeyError(f"Metadata key {key!r} already exists") from exc
75 update = (
76 sqlalchemy.sql.update(self._table).where(self._table.columns.name == key).values(value=value)
77 )
78 with self._engine.begin() as conn:
79 result = conn.execute(update)
80 if result.rowcount != 1:
81 raise RuntimeError(f"Metadata update failed unexpectedly, count={result.rowcount}")
82
◆ table_exists()
| bool lsst.dax.apdb.sql.apdbMetadataSql.ApdbMetadataSql.table_exists | ( | self | ) |
Return `True` if metadata table exists.
Definition at line 115 of file apdbMetadataSql.py.
115 def table_exists(self) -> bool:
116 """Return `True` if metadata table exists."""
117 return self._table is not None
Member Data Documentation
◆ _engine
|
protected |
Definition at line 46 of file apdbMetadataSql.py.
◆ _table
|
protected |
Definition at line 47 of file apdbMetadataSql.py.
The documentation for this class was generated from the following file:
- /j/snowflake/release/lsstsw/stack/lsst-scipipe-8.0.0/Linux64/dax_apdb/g88963caddf+0cb8e002cc/python/lsst/dax/apdb/sql/apdbMetadataSql.py
