# Copyright 2019 Google LLC

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

# https://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

"""Holds table-specific information to make querying spanner eaiser."""

import collections

import copy

from typing import Any, Callable, Dict, Iterable, List, Optional, Type, TypeVar, Union

from spanner_orm import api

from spanner_orm import condition

from spanner_orm import error

from spanner_orm import foreign_key_relationship

from spanner_orm import field

from spanner_orm import index

from spanner_orm import metadata

from spanner_orm import query

from spanner_orm import registry

from spanner_orm import relationship

from spanner_orm import table_apis

from google.api_core import exceptions

from google.cloud import spanner

from google.cloud.spanner_v1 import transaction as spanner_transaction

T = TypeVar('T')

class ModelMetaclass(type):

"""Populates ModelMetadata based on class attributes."""

meta: metadata.ModelMetadata

def __new__(mcs, name: str, bases: Any, attrs: Dict[str, Any], **kwargs: Any):

parents = [base for base in bases if isinstance(base, ModelMetaclass)]

model_metadata = metadata.ModelMetadata()

for parent in parents:

if 'meta' in vars(parent):

model_metadata.add_metadata(parent.meta)

non_model_attrs = {}

for key, value in attrs.items():

if key == '__table__':

model_metadata.table = value

elif key == '__interleaved__':

model_metadata.interleaved = value

if isinstance(value, field.Field):

model_metadata.add_field(key, value)

elif isinstance(value, index.Index):

model_metadata.add_index(key, value)

elif isinstance(value, relationship.Relationship):

model_metadata.add_relation(key, value)

elif isinstance(

value,

foreign_key_relationship.ForeignKeyRelationship,

):

model_metadata.add_foreign_key_relation(key, value)

else:

non_model_attrs[key] = value

cls = super().__new__(mcs, name, bases, non_model_attrs, **kwargs)

# If a table is set, this class represents a complete model, so finalize

# the metadata

if model_metadata.table:

model_metadata.model_class = cls

model_metadata.finalize()

cls.meta = model_metadata

return cls

def __getattr__(

cls, name: str

) -> Union[field.Field, relationship.Relationship,

foreign_key_relationship.ForeignKeyRelationship, index.Index]:

# Unclear why pylint doesn't like this

# pylint: disable=unsupported-membership-test

if name in cls.fields:

return cls.fields[name]

elif name in cls.relations:

return cls.relations[name]

elif name in cls.foreign_key_relations:

return cls.foreign_key_relations[name]

elif name in cls.indexes:

return cls.indexes[name]

# pylint: enable=unsupported-membership-test

raise AttributeError(name)

@property

def column_prefix(cls) -> str:

return cls.table.split('.')[-1]

# Table fields class methods

@property

def columns(cls) -> List[str]:

return cls.meta.columns

@property

def indexes(cls) -> Dict[str, index.Index]:

return cls.meta.indexes

@property

def interleaved(cls) -> Optional[Type['Model']]:

if cls.meta.interleaved:

return registry.model_registry().get(cls.meta.interleaved)

return None

@property

def primary_keys(cls) -> List[str]:

return cls.meta.primary_keys

@property

def relations(cls) -> Dict[str, relationship.Relationship]:

return cls.meta.relations

@property

def foreign_key_relations(

cls) -> Dict[str, foreign_key_relationship.ForeignKeyRelationship]:

return cls.meta.foreign_key_relations

@property

def fields(cls) -> Dict[str, field.Field]:

return cls.meta.fields

@property

def table(cls):

return cls.meta.table

def validate_value(cls, field_name, value, error_type=error.SpannerError):

try:

cls.fields[field_name].validate(value)

except error.ValidationError as ex:

context = f'Validation error for field {field_name!r}'

raise error_type((f'{context}: {ex.args[0]}' if ex.args else context),

*ex.args[1:])

CallableReturn = TypeVar('CallableReturn')

class Model(metaclass=ModelMetaclass):

"""Maps to a table in spanner and has basic functions for querying tables.

Note: all methods in this class should only be called on subclasses that have

associated tables. Violating this will cause an exception to be raised.

"""

def __init__(self,

values: Dict[str, Any],

persisted: bool = False,

skip_validation: bool = False):

start_values = {}

self.__dict__['start_values'] = start_values

self.__dict__['_persisted'] = persisted

# If the values came from Spanner or validation is explicitly skipped, trust

# them and skip validation

if not persisted and not skip_validation:

# An object is invalid if primary key values are missing

missing_keys = set(self._primary_keys) - set(values.keys())

if missing_keys:

raise error.SpannerError(

'All primary keys must be specified. Missing: {keys}'.format(

keys=missing_keys))

for column in self._columns:

self._metaclass.validate_value(column, values.get(column), ValueError)

for column in self._columns:

value = values.get(column)

start_values[column] = copy.copy(value)

self.__dict__[column] = value

for relation in self._relations:

if relation in values:

self.__dict__[relation] = values[relation]

for foreign_key_relation in self._foreign_key_relations:

if foreign_key_relation in values:

self.__dict__[foreign_key_relation] = values[foreign_key_relation]

def __eq__(self, other: Any) -> Union[bool, type(NotImplemented)]:

"""Compares objects by their type and attributes."""

if type(self) != type(other):

return NotImplemented

return self.values == other.values

def __repr__(self) -> str:

return f'{self.__class__.__qualname__}({self.values!r})'

@classmethod

def spanner_api(cls) -> api.SpannerApi:

if not cls.table:

raise error.SpannerError('Class must define a table for API calls')

return api.spanner_api()

# Table read methods

@classmethod

def all(

cls: Type[T],

*,

transaction: Optional[spanner_transaction.Transaction] = None,

) -> List[T]:

"""Returns all objects of this type stored in Spanner.

Note: this method should only be called on subclasses of Model that have

a table associated with it. Violating this will cause an exception to be

raised.

Args:

transaction: The existing transaction to use, or None to start a new

transaction

Returns:

A list of models, one per row in the associated Spanner table

"""

args = [cls.table, cls.columns, spanner.KeySet(all_=True)]

results = cls._execute_read(table_apis.find, transaction, args)

return cls._results_to_models(results)

@classmethod

def count(

cls,

*conditions: condition.Condition,

transaction: Optional[spanner_transaction.Transaction] = None,

) -> int:

"""Returns the number of objects in Spanner that match the given conditions.

Args:

*conditions: Instances of subclasses of Condition that help specify which

rows should be included in the count. The includes condition is not

allowed here

transaction: The existing transaction to use, or None to start a new

transaction

Returns:

The integer result of the COUNT query

"""

builder = query.CountQuery(cls, conditions)

args = [builder.sql(), builder.parameters(), builder.types()]

results = cls._execute_read(table_apis.sql_query, transaction, args)

return builder.process_results(results)

@classmethod

def count_equal(

cls,

*,

transaction: Optional[spanner_transaction.Transaction] = None,

**constraints: Any,

) -> int:

"""Returns the number of objects in Spanner that match the given conditions.

Convenience method that generates equality conditions based on the keyword

arguments.

Args:

transaction: The existing transaction to use, or None to start a new

transaction

**constraints: Each key/value pair is turned into an equality condition:

the key is used as the column in the condition and the value is used as

the value to compare the column against in the query.

Returns:

The integer result of the COUNT query

"""

conditions = []

for column, value in constraints.items():

if isinstance(value, list):

conditions.append(condition.in_list(column, value))

else:

conditions.append(condition.equal_to(column, value))

return cls.count(*conditions, transaction=transaction)

@classmethod

def find(

cls: Type[T],

*,

transaction: Optional[spanner_transaction.Transaction] = None,

**keys: Any,

) -> Optional[T]:

"""Retrieves an object from Spanner based on the provided key.

Args:

transaction: The existing transaction to use, or None to start a new

transaction

**keys: The keys provided are the complete set of primary keys for this

table and the corresponding values make up the unique identifier of the

object being retrieved

Returns:

The requested object or None if no such object exists

"""

resources = cls.find_multi([keys], transaction=transaction)

return resources[0] if resources else None

@classmethod

def find_required(

cls: Type[T],

*,

transaction: Optional[spanner_transaction.Transaction] = None,

**keys: Any,

) -> T:

"""Retrieves an object from Spanner based on the provided key.

Args:

transaction: The existing transaction to use, or None to start a new

transaction

**keys: The keys provided are the complete set of primary keys for this

table and the corresponding values make up the unique identifier of the

object being retrieved

Returns:

The requested object.

Raises:

exceptions.NotFound: The object wasn't found.

"""

result = cls.find(**keys, transaction=transaction)

if result is None:

raise exceptions.NotFound(

f'{cls.__qualname__} has no object with primary key {keys}')

return result

@classmethod

def find_multi(

cls: Type[T],

keys: Iterable[Dict[str, Any]],

*,

transaction: Optional[spanner_transaction.Transaction] = None,

) -> List[T]:

"""Retrieves objects from Spanner based on the provided keys.

Args:

keys: An iterable of dictionaries, each dictionary representing the set of

primary key values necessary to uniquely identify an object in this

table.

transaction: The existing transaction to use, or None to start a new

transaction

Returns:

A list containing all requested objects that exist in the table (can be

an empty list)

"""

key_values = []

for key in keys:

key_values.append([key[column] for column in cls.primary_keys])

keyset = spanner.KeySet(keys=key_values)

args = [cls.table, cls.columns, keyset]

results = cls._execute_read(table_apis.find, transaction, args)

return cls._results_to_models(results)

@classmethod

def where(

cls: Type[T],

*conditions: condition.Condition,

transaction: Optional[spanner_transaction.Transaction] = None,

) -> List[T]:

"""Retrieves objects from Spanner based on the provided conditions.

Args:

*conditions: Instances of subclasses of Condition that help specify which

objects should be retrieved

transaction: The existing transaction to use, or None to start a new

transaction

Returns:

A list containing all requested objects that exist in the table (can be

an empty list)

"""

builder = query.SelectQuery(cls, conditions)

args = [builder.sql(), builder.parameters(), builder.types()]

results = cls._execute_read(table_apis.sql_query, transaction, args)

return builder.process_results(results)

@classmethod

def where_equal(

cls: Type[T],

*,

transaction: Optional[spanner_transaction.Transaction] = None,

**constraints: Any,

) -> List[T]:

"""Retrieves objects from Spanner based on the provided constraints.

Args:

transaction: The existing transaction to use, or None to start a new

transaction

**constraints: Each key/value pair is turned into an equality condition:

the key is used as the column in the condition and the value is used as

the value to compare the column against in the query.

Returns:

A list containing all requested objects that exist in the table (can be

an empty list)

"""

conditions = []

for column, value in constraints.items():

if isinstance(value, list):

conditions.append(condition.in_list(column, value))

else:

conditions.append(condition.equal_to(column, value))

return cls.where(*conditions, transaction=transaction)

@classmethod

def _results_to_models(

cls: Type[T],

results: Iterable[Iterable[Any]],

) -> List[T]:

items = [dict(zip(cls.columns, result)) for result in results]

return [cls(item, persisted=True) for item in items]

@classmethod

def _execute_read(

cls,

db_api: Callable[..., CallableReturn],

transaction: Optional[spanner_transaction.Transaction],

args: List[Any],

) -> CallableReturn:

if transaction is not None:

return db_api(transaction, *args)

else:

return cls.spanner_api().run_read_only(db_api, *args)

# Table write methods

@classmethod

def create(

cls,

*,

transaction: Optional[spanner_transaction.Transaction] = None,

**kwargs: Any,

) -> None:

"""Creates a row in Spanner based on the provided data.

Note: may throw an exception if bad values are provided.

Args:

transaction: The existing transaction to use, or None to start a new

transaction

**kwargs: The keys are columns on the table and the values are the values

each column in the table should be set to. None and keys not present

indicate the corresponding column value should be NULL.

"""

cls._execute_write(table_apis.insert, transaction, [kwargs])

@classmethod

def create_or_update(

cls,

*,

transaction: Optional[spanner_transaction.Transaction] = None,

**kwargs: Any,

) -> None:

cls._execute_write(table_apis.upsert, transaction, [kwargs])

@classmethod

def _delete_by_keyset(

cls,

transaction: Optional[spanner_transaction.Transaction],

keyset: spanner.KeySet,

) -> None:

db_api = table_apis.delete

args = [cls.table, keyset]

if transaction is not None:

db_api(transaction, *args)

else:

cls.spanner_api().run_write(db_api, *args)

@classmethod

def delete_batch(

cls: Type[T],

models: List[T],

*,

transaction: Optional[spanner_transaction.Transaction] = None,

) -> None:

"""Deletes rows from Spanner based on the provided models' primary keys.

Args:

models: A list of models to be deleted from Spanner.

transaction: The existing transaction to use, or None to start a new

transaction

"""

key_list = []

for model in models:

key_list.append([getattr(model, column) for column in cls.primary_keys])

cls._delete_by_keyset(

transaction=transaction,

keyset=spanner.KeySet(keys=key_list),

)

@classmethod

def delete_by_key(

cls,

*,

transaction: Optional[spanner_transaction.Transaction] = None,

**keys: Any,

) -> None:

"""Deletes rows from Spanner based on the provided primary key.

Args:

transaction: The existing transaction to use, or None to start a new

transaction.

**keys: The keys provided are the complete set of primary keys for this

table and the corresponding values make up the unique identifier of the

object being deleted.

"""

cls._delete_by_keyset(

transaction=transaction,

keyset=spanner.KeySet(

keys=[[keys[column] for column in cls.primary_keys]]),

)

@classmethod

def save_batch(

cls: Type[T],

models: List[T],

*,

transaction: Optional[spanner_transaction.Transaction] = None,

force_write: bool = False,

) -> None:

"""Writes rows to Spanner based on the provided model data.

Args:

models: A list of models to be written to Spanner. If the _persisted flag

is set, by default we try to issue an UPDATE with values set for all

columns in the table. Otherwise, we try to issue an INSERT for all

columns in the table. If we try to INSERTa row that already exists (or

update one that is missing), an exception will be thrown.

transaction: The existing transaction to use, or None to start a new

transaction

force_write: If true, we use UPSERT instead of UPDATE/INSERT, so no

exceptions are thrown based on the presence or absence of data in

Spanner

"""

work = collections.defaultdict(list)

for model in models:

value = {column: getattr(model, column) for column in cls.columns}

if force_write:

api_method = table_apis.upsert

elif model._persisted: # pylint: disable=protected-access

api_method = table_apis.update

else:

api_method = table_apis.insert

work[api_method].append(value)

model._persisted = True # pylint: disable=protected-access

for api_method, values in work.items():

cls._execute_write(api_method, transaction, values)

@classmethod

def update(

cls,

*,

transaction: Optional[spanner_transaction.Transaction] = None,

**kwargs: Any,

) -> None:

"""Updates a row in Spanner based on the provided data.

Args:

transaction: The existing transaction to use, or None to start a new

transaction

**kwargs: The keys are columns on the table and the values are the values

each column in the table should be set to. None indicates indicate the

corresponding column value should be NULL and not present keys indicate

the corresponding column value should not be changed.

"""

cls._execute_write(table_apis.update, transaction, [kwargs])

@classmethod

def _execute_write(

cls,

db_api: Callable[..., Any],

transaction: Optional[spanner_transaction.Transaction],

dictionaries: Iterable[Dict[str, Any]],

) -> None:

"""Validates all write value types and commits write to Spanner."""

columns, values = None, []

for dictionary in dictionaries:

invalid_keys = set(dictionary.keys()) - set(cls.columns)

if invalid_keys:

raise error.SpannerError('Invalid keys set on {model}: {keys}'.format(

model=cls.__name__, keys=invalid_keys))

if columns is None:

columns = dictionary.keys()

if columns != dictionary.keys():

raise error.SpannerError(

'Attempted to update rows with different sets of keys')

for key, value in dictionary.items():

cls.validate_value(key, value, error.SpannerError)

values.append([dictionary[column] for column in columns])

args = [cls.table, columns, values]

if transaction is not None:

return db_api(transaction, *args)

else:

return cls.spanner_api().run_write(db_api, *args)

def __setattr__(self, name: str, value: Any) -> None:

if name in self._relations:

raise AttributeError(name)

elif name in self._fields:

if name in self._primary_keys:

raise AttributeError(name)

self._metaclass.validate_value(name, value, AttributeError)

super().__setattr__(name, value)

@property

def _metaclass(self) -> Type['Model']:

return type(self)

@property

def _columns(self) -> List[str]:

return self._metaclass.columns

@property

def _fields(self) -> Dict[str, field.Field]:

return self._metaclass.fields

@property

def _primary_keys(self) -> List[str]:

return self._metaclass.primary_keys

@property

def _relations(self) -> Dict[str, relationship.Relationship]:

return self._metaclass.relations

@property

def _foreign_key_relations(

self) -> Dict[str, foreign_key_relationship.ForeignKeyRelationship]:

return self._metaclass.foreign_key_relations

@property

def _table(self) -> str:

return self._metaclass.table

@property

def values(self) -> Dict[str, Any]:

"""Gets all attributes.

Returns:

Dictionary mapping from attribute name to value.

"""

return {key: getattr(self, key) for key in self._columns}

def changes(self) -> Dict[str, Any]:

"""Gets all attributes that have been updated since object creation.

Returns:

Dictionary mapping from changed attribute name to new value.

"""

values = self.values

return {

key: values[key]

for key in self._columns

if values[key] != self.start_values.get(key)

}

def delete(

self,

*,

transaction: Optional[spanner_transaction.Transaction] = None,

) -> None:

"""Deletes this object from the Spanner database.

Args:

transaction: The existing transaction to use, or None to start a new

transaction

"""

key = [getattr(self, column) for column in self._primary_keys]

keyset = spanner.KeySet([key])

db_api = table_apis.delete

args = [self._table, keyset]

if transaction is not None:

db_api(transaction, *args)

else:

self.spanner_api().run_write(db_api, *args)

def id(self) -> Dict[str, Any]:

"""Gets the identifier of this object.

Returns:

Dictionary mapping from primary key attribute name to values. Note: this

dictionary can be used with Model.find to return the updated version of

this object from Spanner.

"""

return {key: self.values[key] for key in self._primary_keys}

def reload(

self,

*,

transaction: Optional[spanner_transaction.Transaction] = None,

) -> Optional['Model']:

"""Refreshes this object with information from Spanner.

Args:

transaction: The existing transaction to use, or None to start a new

transaction

Returns:

This object updated with the appropriate values if information was found

in Spanner, or None if no information was found (object was deleted or

never was persisted)

"""

updated_object = self._metaclass.find(transaction=transaction, **self.id())

if updated_object is None:

return None

start_values = {}

for column in self._columns:

value = getattr(updated_object, column)

start_values[column] = copy.copy(value)

if column not in self._primary_keys:

setattr(self, column, value)

self.start_values = start_values

self._persisted = True

return self

def save(

self,

*,

transaction: Optional[spanner_transaction.Transaction] = None,

) -> 'Model':

"""Persists this object to Spanner.

Note: if the _persisted flag doesn't match whether this object is actually

stored in Spanner, an exception may be thrown due to using the wrong

API.

Args:

transaction: The existing transaction to use, or None to start a new

transaction

Returns:

The current object

"""

if self._persisted:

changed_values = self.changes()

if changed_values:

changed_values.update(self.id())

self._metaclass.update(transaction=transaction, **changed_values)

else:

self._metaclass.create(transaction=transaction, **self.values)

self._persisted = True

return self