def get_metadata(self, key=None):
"""Retrieve a value from the key-value store
in the database's metadata table.
If `key` is |None| all of the keys will be retrieved
and returned as a |dict|.
Parameters
----------
key : str, optional
The key value to retrieve.
Returns
-------
any or |dict|
"""
if key is None:
return {
row[0]: pickle.loads(bytes(row[1])) for row in self.execute("SELECT name, content FROM metadata")
}
res = [pickle.loads(bytes(row[0])) for row in self.execute("SELECT content FROM metadata WHERE name = ?", (key,))]
if len(res) > 0:
return res[0]
else:
raise KeyError("Key {} not found".format(key))
def from_sql(cls, row, *args, **kwargs):
'''
Translate a Row object from sqlite3 into a GlycanRecord object
Parameters
----------
row: sqlite3.Row
A dict-like object containing the pickled value of the record in
the `structure` field
Returns
-------
GlycanRecord:
The unpickled :class:`GlycanRecord` object. Sub-classes may perform
more complex operations like decompressing or joining other tables in
the database.
'''
record = pickle.loads(bytes(row["structure"]))
record._bound_db = kwargs.get("database")
return record