mirror of
https://github.com/janeczku/calibre-web
synced 2024-11-16 14:54:55 +00:00
527 lines
19 KiB
Python
527 lines
19 KiB
Python
# engine/reflection.py
|
|
# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <see AUTHORS file>
|
|
#
|
|
# This module is part of SQLAlchemy and is released under
|
|
# the MIT License: http://www.opensource.org/licenses/mit-license.php
|
|
|
|
"""Provides an abstraction for obtaining database schema information.
|
|
|
|
Usage Notes:
|
|
|
|
Here are some general conventions when accessing the low level inspector
|
|
methods such as get_table_names, get_columns, etc.
|
|
|
|
1. Inspector methods return lists of dicts in most cases for the following
|
|
reasons:
|
|
|
|
* They're both standard types that can be serialized.
|
|
* Using a dict instead of a tuple allows easy expansion of attributes.
|
|
* Using a list for the outer structure maintains order and is easy to work
|
|
with (e.g. list comprehension [d['name'] for d in cols]).
|
|
|
|
2. Records that contain a name, such as the column name in a column record
|
|
use the key 'name'. So for most return values, each record will have a
|
|
'name' attribute..
|
|
"""
|
|
|
|
from .. import exc, sql
|
|
from .. import schema as sa_schema
|
|
from .. import util
|
|
from ..types import TypeEngine
|
|
from ..util import deprecated
|
|
from ..util import topological
|
|
from .. import inspection
|
|
from .base import Connectable
|
|
|
|
|
|
@util.decorator
|
|
def cache(fn, self, con, *args, **kw):
|
|
info_cache = kw.get('info_cache', None)
|
|
if info_cache is None:
|
|
return fn(self, con, *args, **kw)
|
|
key = (
|
|
fn.__name__,
|
|
tuple(a for a in args if isinstance(a, basestring)),
|
|
tuple((k, v) for k, v in kw.iteritems() if isinstance(v, (basestring, int, float)))
|
|
)
|
|
ret = info_cache.get(key)
|
|
if ret is None:
|
|
ret = fn(self, con, *args, **kw)
|
|
info_cache[key] = ret
|
|
return ret
|
|
|
|
|
|
class Inspector(object):
|
|
"""Performs database schema inspection.
|
|
|
|
The Inspector acts as a proxy to the reflection methods of the
|
|
:class:`~sqlalchemy.engine.interfaces.Dialect`, providing a
|
|
consistent interface as well as caching support for previously
|
|
fetched metadata.
|
|
|
|
A :class:`.Inspector` object is usually created via the
|
|
:func:`.inspect` function::
|
|
|
|
from sqlalchemy import inspect, create_engine
|
|
engine = create_engine('...')
|
|
insp = inspect(engine)
|
|
|
|
The inspection method above is equivalent to using the
|
|
:meth:`.Inspector.from_engine` method, i.e.::
|
|
|
|
engine = create_engine('...')
|
|
insp = Inspector.from_engine(engine)
|
|
|
|
Where above, the :class:`~sqlalchemy.engine.interfaces.Dialect` may opt
|
|
to return an :class:`.Inspector` subclass that provides additional
|
|
methods specific to the dialect's target database.
|
|
|
|
"""
|
|
|
|
def __init__(self, bind):
|
|
"""Initialize a new :class:`.Inspector`.
|
|
|
|
:param bind: a :class:`~sqlalchemy.engine.Connectable`,
|
|
which is typically an instance of
|
|
:class:`~sqlalchemy.engine.Engine` or
|
|
:class:`~sqlalchemy.engine.Connection`.
|
|
|
|
For a dialect-specific instance of :class:`.Inspector`, see
|
|
:meth:`.Inspector.from_engine`
|
|
|
|
"""
|
|
# this might not be a connection, it could be an engine.
|
|
self.bind = bind
|
|
|
|
# set the engine
|
|
if hasattr(bind, 'engine'):
|
|
self.engine = bind.engine
|
|
else:
|
|
self.engine = bind
|
|
|
|
if self.engine is bind:
|
|
# if engine, ensure initialized
|
|
bind.connect().close()
|
|
|
|
self.dialect = self.engine.dialect
|
|
self.info_cache = {}
|
|
|
|
@classmethod
|
|
def from_engine(cls, bind):
|
|
"""Construct a new dialect-specific Inspector object from the given
|
|
engine or connection.
|
|
|
|
:param bind: a :class:`~sqlalchemy.engine.Connectable`,
|
|
which is typically an instance of
|
|
:class:`~sqlalchemy.engine.Engine` or
|
|
:class:`~sqlalchemy.engine.Connection`.
|
|
|
|
This method differs from direct a direct constructor call of
|
|
:class:`.Inspector` in that the
|
|
:class:`~sqlalchemy.engine.interfaces.Dialect` is given a chance to
|
|
provide a dialect-specific :class:`.Inspector` instance, which may
|
|
provide additional methods.
|
|
|
|
See the example at :class:`.Inspector`.
|
|
|
|
"""
|
|
if hasattr(bind.dialect, 'inspector'):
|
|
return bind.dialect.inspector(bind)
|
|
return Inspector(bind)
|
|
|
|
@inspection._inspects(Connectable)
|
|
def _insp(bind):
|
|
return Inspector.from_engine(bind)
|
|
|
|
@property
|
|
def default_schema_name(self):
|
|
"""Return the default schema name presented by the dialect
|
|
for the current engine's database user.
|
|
|
|
E.g. this is typically ``public`` for Postgresql and ``dbo``
|
|
for SQL Server.
|
|
|
|
"""
|
|
return self.dialect.default_schema_name
|
|
|
|
def get_schema_names(self):
|
|
"""Return all schema names.
|
|
"""
|
|
|
|
if hasattr(self.dialect, 'get_schema_names'):
|
|
return self.dialect.get_schema_names(self.bind,
|
|
info_cache=self.info_cache)
|
|
return []
|
|
|
|
def get_table_names(self, schema=None, order_by=None):
|
|
"""Return all table names in referred to within a particular schema.
|
|
|
|
The names are expected to be real tables only, not views.
|
|
Views are instead returned using the :meth:`.get_view_names`
|
|
method.
|
|
|
|
|
|
:param schema: Schema name. If ``schema`` is left at ``None``, the
|
|
database's default schema is
|
|
used, else the named schema is searched. If the database does not
|
|
support named schemas, behavior is undefined if ``schema`` is not
|
|
passed as ``None``.
|
|
|
|
:param order_by: Optional, may be the string "foreign_key" to sort
|
|
the result on foreign key dependencies.
|
|
|
|
.. versionchanged:: 0.8 the "foreign_key" sorting sorts tables
|
|
in order of dependee to dependent; that is, in creation
|
|
order, rather than in drop order. This is to maintain
|
|
consistency with similar features such as
|
|
:attr:`.MetaData.sorted_tables` and :func:`.util.sort_tables`.
|
|
|
|
.. seealso::
|
|
|
|
:attr:`.MetaData.sorted_tables`
|
|
|
|
"""
|
|
|
|
if hasattr(self.dialect, 'get_table_names'):
|
|
tnames = self.dialect.get_table_names(self.bind,
|
|
schema, info_cache=self.info_cache)
|
|
else:
|
|
tnames = self.engine.table_names(schema)
|
|
if order_by == 'foreign_key':
|
|
tuples = []
|
|
for tname in tnames:
|
|
for fkey in self.get_foreign_keys(tname, schema):
|
|
if tname != fkey['referred_table']:
|
|
tuples.append((fkey['referred_table'], tname))
|
|
tnames = list(topological.sort(tuples, tnames))
|
|
return tnames
|
|
|
|
def get_table_options(self, table_name, schema=None, **kw):
|
|
"""Return a dictionary of options specified when the table of the
|
|
given name was created.
|
|
|
|
This currently includes some options that apply to MySQL tables.
|
|
|
|
"""
|
|
if hasattr(self.dialect, 'get_table_options'):
|
|
return self.dialect.get_table_options(
|
|
self.bind, table_name, schema,
|
|
info_cache=self.info_cache, **kw)
|
|
return {}
|
|
|
|
def get_view_names(self, schema=None):
|
|
"""Return all view names in `schema`.
|
|
|
|
:param schema: Optional, retrieve names from a non-default schema.
|
|
"""
|
|
|
|
return self.dialect.get_view_names(self.bind, schema,
|
|
info_cache=self.info_cache)
|
|
|
|
def get_view_definition(self, view_name, schema=None):
|
|
"""Return definition for `view_name`.
|
|
|
|
:param schema: Optional, retrieve names from a non-default schema.
|
|
"""
|
|
|
|
return self.dialect.get_view_definition(
|
|
self.bind, view_name, schema, info_cache=self.info_cache)
|
|
|
|
def get_columns(self, table_name, schema=None, **kw):
|
|
"""Return information about columns in `table_name`.
|
|
|
|
Given a string `table_name` and an optional string `schema`, return
|
|
column information as a list of dicts with these keys:
|
|
|
|
name
|
|
the column's name
|
|
|
|
type
|
|
:class:`~sqlalchemy.types.TypeEngine`
|
|
|
|
nullable
|
|
boolean
|
|
|
|
default
|
|
the column's default value
|
|
|
|
attrs
|
|
dict containing optional column attributes
|
|
"""
|
|
|
|
col_defs = self.dialect.get_columns(self.bind, table_name, schema,
|
|
info_cache=self.info_cache,
|
|
**kw)
|
|
for col_def in col_defs:
|
|
# make this easy and only return instances for coltype
|
|
coltype = col_def['type']
|
|
if not isinstance(coltype, TypeEngine):
|
|
col_def['type'] = coltype()
|
|
return col_defs
|
|
|
|
@deprecated('0.7', 'Call to deprecated method get_primary_keys.'
|
|
' Use get_pk_constraint instead.')
|
|
def get_primary_keys(self, table_name, schema=None, **kw):
|
|
"""Return information about primary keys in `table_name`.
|
|
|
|
Given a string `table_name`, and an optional string `schema`, return
|
|
primary key information as a list of column names.
|
|
"""
|
|
|
|
return self.dialect.get_pk_constraint(self.bind, table_name, schema,
|
|
info_cache=self.info_cache,
|
|
**kw)['constrained_columns']
|
|
|
|
def get_pk_constraint(self, table_name, schema=None, **kw):
|
|
"""Return information about primary key constraint on `table_name`.
|
|
|
|
Given a string `table_name`, and an optional string `schema`, return
|
|
primary key information as a dictionary with these keys:
|
|
|
|
constrained_columns
|
|
a list of column names that make up the primary key
|
|
|
|
name
|
|
optional name of the primary key constraint.
|
|
|
|
"""
|
|
return self.dialect.get_pk_constraint(self.bind, table_name, schema,
|
|
info_cache=self.info_cache,
|
|
**kw)
|
|
|
|
def get_foreign_keys(self, table_name, schema=None, **kw):
|
|
"""Return information about foreign_keys in `table_name`.
|
|
|
|
Given a string `table_name`, and an optional string `schema`, return
|
|
foreign key information as a list of dicts with these keys:
|
|
|
|
constrained_columns
|
|
a list of column names that make up the foreign key
|
|
|
|
referred_schema
|
|
the name of the referred schema
|
|
|
|
referred_table
|
|
the name of the referred table
|
|
|
|
referred_columns
|
|
a list of column names in the referred table that correspond to
|
|
constrained_columns
|
|
|
|
name
|
|
optional name of the foreign key constraint.
|
|
|
|
\**kw
|
|
other options passed to the dialect's get_foreign_keys() method.
|
|
|
|
"""
|
|
|
|
return self.dialect.get_foreign_keys(self.bind, table_name, schema,
|
|
info_cache=self.info_cache,
|
|
**kw)
|
|
|
|
def get_indexes(self, table_name, schema=None, **kw):
|
|
"""Return information about indexes in `table_name`.
|
|
|
|
Given a string `table_name` and an optional string `schema`, return
|
|
index information as a list of dicts with these keys:
|
|
|
|
name
|
|
the index's name
|
|
|
|
column_names
|
|
list of column names in order
|
|
|
|
unique
|
|
boolean
|
|
|
|
\**kw
|
|
other options passed to the dialect's get_indexes() method.
|
|
"""
|
|
|
|
return self.dialect.get_indexes(self.bind, table_name,
|
|
schema,
|
|
info_cache=self.info_cache, **kw)
|
|
|
|
def reflecttable(self, table, include_columns, exclude_columns=()):
|
|
"""Given a Table object, load its internal constructs based on
|
|
introspection.
|
|
|
|
This is the underlying method used by most dialects to produce
|
|
table reflection. Direct usage is like::
|
|
|
|
from sqlalchemy import create_engine, MetaData, Table
|
|
from sqlalchemy.engine import reflection
|
|
|
|
engine = create_engine('...')
|
|
meta = MetaData()
|
|
user_table = Table('user', meta)
|
|
insp = Inspector.from_engine(engine)
|
|
insp.reflecttable(user_table, None)
|
|
|
|
:param table: a :class:`~sqlalchemy.schema.Table` instance.
|
|
:param include_columns: a list of string column names to include
|
|
in the reflection process. If ``None``, all columns are reflected.
|
|
|
|
"""
|
|
dialect = self.bind.dialect
|
|
|
|
# table attributes we might need.
|
|
reflection_options = dict(
|
|
(k, table.kwargs.get(k))
|
|
for k in dialect.reflection_options if k in table.kwargs)
|
|
|
|
schema = table.schema
|
|
table_name = table.name
|
|
|
|
# apply table options
|
|
tbl_opts = self.get_table_options(table_name, schema, **table.kwargs)
|
|
if tbl_opts:
|
|
table.kwargs.update(tbl_opts)
|
|
|
|
# table.kwargs will need to be passed to each reflection method. Make
|
|
# sure keywords are strings.
|
|
tblkw = table.kwargs.copy()
|
|
for (k, v) in tblkw.items():
|
|
del tblkw[k]
|
|
tblkw[str(k)] = v
|
|
|
|
# Py2K
|
|
if isinstance(schema, str):
|
|
schema = schema.decode(dialect.encoding)
|
|
if isinstance(table_name, str):
|
|
table_name = table_name.decode(dialect.encoding)
|
|
# end Py2K
|
|
|
|
# columns
|
|
found_table = False
|
|
cols_by_orig_name = {}
|
|
|
|
for col_d in self.get_columns(table_name, schema, **tblkw):
|
|
found_table = True
|
|
orig_name = col_d['name']
|
|
|
|
table.dispatch.column_reflect(self, table, col_d)
|
|
|
|
name = col_d['name']
|
|
if include_columns and name not in include_columns:
|
|
continue
|
|
if exclude_columns and name in exclude_columns:
|
|
continue
|
|
|
|
coltype = col_d['type']
|
|
col_kw = {
|
|
'nullable': col_d['nullable'],
|
|
}
|
|
for k in ('autoincrement', 'quote', 'info', 'key'):
|
|
if k in col_d:
|
|
col_kw[k] = col_d[k]
|
|
|
|
colargs = []
|
|
if col_d.get('default') is not None:
|
|
# the "default" value is assumed to be a literal SQL
|
|
# expression, so is wrapped in text() so that no quoting
|
|
# occurs on re-issuance.
|
|
colargs.append(
|
|
sa_schema.DefaultClause(
|
|
sql.text(col_d['default']), _reflected=True
|
|
)
|
|
)
|
|
|
|
if 'sequence' in col_d:
|
|
# TODO: mssql, maxdb and sybase are using this.
|
|
seq = col_d['sequence']
|
|
sequence = sa_schema.Sequence(seq['name'], 1, 1)
|
|
if 'start' in seq:
|
|
sequence.start = seq['start']
|
|
if 'increment' in seq:
|
|
sequence.increment = seq['increment']
|
|
colargs.append(sequence)
|
|
|
|
cols_by_orig_name[orig_name] = col = \
|
|
sa_schema.Column(name, coltype, *colargs, **col_kw)
|
|
|
|
table.append_column(col)
|
|
|
|
if not found_table:
|
|
raise exc.NoSuchTableError(table.name)
|
|
|
|
# Primary keys
|
|
pk_cons = self.get_pk_constraint(table_name, schema, **tblkw)
|
|
if pk_cons:
|
|
pk_cols = [
|
|
cols_by_orig_name[pk]
|
|
for pk in pk_cons['constrained_columns']
|
|
if pk in cols_by_orig_name and pk not in exclude_columns
|
|
]
|
|
pk_cols += [
|
|
pk
|
|
for pk in table.primary_key
|
|
if pk.key in exclude_columns
|
|
]
|
|
primary_key_constraint = sa_schema.PrimaryKeyConstraint(
|
|
name=pk_cons.get('name'),
|
|
*pk_cols
|
|
)
|
|
|
|
table.append_constraint(primary_key_constraint)
|
|
|
|
# Foreign keys
|
|
fkeys = self.get_foreign_keys(table_name, schema, **tblkw)
|
|
for fkey_d in fkeys:
|
|
conname = fkey_d['name']
|
|
# look for columns by orig name in cols_by_orig_name,
|
|
# but support columns that are in-Python only as fallback
|
|
constrained_columns = [
|
|
cols_by_orig_name[c].key
|
|
if c in cols_by_orig_name else c
|
|
for c in fkey_d['constrained_columns']
|
|
]
|
|
if exclude_columns and set(constrained_columns).intersection(
|
|
exclude_columns):
|
|
continue
|
|
referred_schema = fkey_d['referred_schema']
|
|
referred_table = fkey_d['referred_table']
|
|
referred_columns = fkey_d['referred_columns']
|
|
refspec = []
|
|
if referred_schema is not None:
|
|
sa_schema.Table(referred_table, table.metadata,
|
|
autoload=True, schema=referred_schema,
|
|
autoload_with=self.bind,
|
|
**reflection_options
|
|
)
|
|
for column in referred_columns:
|
|
refspec.append(".".join(
|
|
[referred_schema, referred_table, column]))
|
|
else:
|
|
sa_schema.Table(referred_table, table.metadata, autoload=True,
|
|
autoload_with=self.bind,
|
|
**reflection_options
|
|
)
|
|
for column in referred_columns:
|
|
refspec.append(".".join([referred_table, column]))
|
|
table.append_constraint(
|
|
sa_schema.ForeignKeyConstraint(constrained_columns, refspec,
|
|
conname, link_to_name=True))
|
|
# Indexes
|
|
indexes = self.get_indexes(table_name, schema)
|
|
for index_d in indexes:
|
|
name = index_d['name']
|
|
columns = index_d['column_names']
|
|
unique = index_d['unique']
|
|
flavor = index_d.get('type', 'unknown type')
|
|
if include_columns and \
|
|
not set(columns).issubset(include_columns):
|
|
util.warn(
|
|
"Omitting %s KEY for (%s), key covers omitted columns." %
|
|
(flavor, ', '.join(columns)))
|
|
continue
|
|
# look for columns by orig name in cols_by_orig_name,
|
|
# but support columns that are in-Python only as fallback
|
|
sa_schema.Index(name, *[
|
|
cols_by_orig_name[c] if c in cols_by_orig_name
|
|
else table.c[c]
|
|
for c in columns
|
|
],
|
|
**dict(unique=unique))
|