python-spanner-orm/spanner_orm/metadata.py at v0.1 · google/python-spanner-orm · GitHub

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# python3

# 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

# python3

# 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.

# 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.

"""Hold information about a Model extracted from the class attributes."""

from typing import Any, Dict, Type, Optional

from spanner_orm import error

from spanner_orm import field

from spanner_orm import index

from spanner_orm import registry

from spanner_orm import relationship

class ModelMetadata(object):

"""Hold information about a Model extracted from the class attributes."""

def __init__(self,

table: Optional[str] = None,

fields: Optional[Dict[str, field.Field]] = None,

relations: Optional[Dict[str, relationship.Relationship]] = None,

indexes: Optional[Dict[str, index.Index]] = None,

interleaved: Optional[str] = None,

model_class: Optional[Type[Any]] = None):

self.columns = []

self.fields = dict(fields or {})

self._finalized = False

self.indexes = dict(indexes or {})

self.interleaved = interleaved

self.model_class = model_class

self.primary_keys = []

self.relations = dict(relations or {})

self.table = table or ''

def finalize(self) -> None:

"""Finish generating metadata state.

Some metadata depends on having all configuration data set before it can

be calculated--the primary index, for example, needs all fields to be added

before it can be calculated. This method is called to indicate that all

relevant state has been added and the calculation of the final data should

now happen.

"""

if self._finalized:

raise error.SpannerError('Metadata was already finalized')

sorted_fields = list(sorted(self.fields.values(), key=lambda f: f.position))

if index.Index.PRIMARY_INDEX not in self.indexes:

primary_keys = [f.name for f in sorted_fields if f.primary_key()]

primary_index = index.Index(primary_keys)

primary_index.name = index.Index.PRIMARY_INDEX

self.indexes[index.Index.PRIMARY_INDEX] = primary_index

self.primary_keys = self.indexes[index.Index.PRIMARY_INDEX].columns

self.columns = [f.name for f in sorted_fields]

for _, relation in self.relations.items():

relation.origin = self.model_class

registry.model_registry().register(self.model_class)

self._finalized = True

def add_metadata(self, metadata: 'ModelMetadata') -> None:

self.table = metadata.table or self.table

self.fields.update(metadata.fields)

self.relations.update(metadata.relations)

self.indexes.update(metadata.indexes)

self.interleaved = metadata.interleaved or self.interleaved

def add_field(self, name: str, new_field: field.Field) -> None:

new_field.name = name

new_field.position = len(self.fields)

self.fields[name] = new_field

def add_relation(self, name: str,

new_relation: relationship.Relationship) -> None:

new_relation.name = name

self.relations[name] = new_relation

def add_index(self, name: str, new_index: index.Index) -> None:

new_index.name = name

self.indexes[name] = new_index

python-spanner-orm/spanner_orm/metadata.py at v0.1 · google/python-spanner-orm · GitHub

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