Data layer

A data layer is a CRUD interface between resource methods and data providers or ORMs. The data layer class must implement the BaseDataLayer class. You can use one of the provided default classes:

• Sqlalchemy
• Mongodb

But you can also create a custom one that better fits your needs.

Usage example:

from flask_rest_jsonapi import ResourceList, SqlalchemyDataLayer

from your_project.models import Post
from your_project.schemas import PostSchema
from your_project.extensions import sql_db

def get_base_query(self, **view_kwargs):
    query = self.session.query(Post)


class PostList(ResourceList):
    class Meta:
        data_layer = {'cls': SqlalchemyDataLayer,
                      'kwargs': {'model': Post, 'session': sql_db.session},
                      'get_base_query': get_base_query}

    resource_type = 'post'
    schema = {'cls': PostSchema}
    endpoint = {'name': 'post_list'}

Sqlalchemy

A data layer around SQLAlchemy

ResourceList

Instance attributes:

• model (Model): sqlalchemy model
• session (Session): sqlalchemy session instance

Class attributes:

• get_base_query (callable): a callable to retrieve the base data in GET method
• before_create_instance (callable) Optional: additional operations before creating an instance in the POST method

Example:

import datetime

from sqlalchemy import NoResultFound
from flask_rest_jsonapi import ResourceList, SqlalchemyDataLayer

from your_project.models import Post
from your_project.schemas import PostSchema
from your_project.extensions import sql_db
from your_project.lib import get_topic


def get_base_query(self, **view_kwargs):
    query = self.session.query(Post)


def before_create_instance(self, data, **view_kwargs):
    """Make additional work before to create your instance:
        - make checks
        - retrieve a related object to plug to the instance
        - compute an instance attribut
        - or what ever you want.
    """
    try:
        topic = self.session.query(Topic).filter_by(topic_id=view_kwargs['topic_id']).one()
    except NoReultFOund:
        abort(404)

    data['topic'] = topic
    data['created'] = datetime.datetime.utcnow()


class PostList(ResourceList):
    class Meta:
        data_layer = {'cls': SqlalchemyDataLayer,
                      'kwargs': {'model': Post, 'session': sql_db.session},
                      'get_base_query': get_base_query,
                      'before_create_instance': before_create_instance}

    resource_type = 'post'
    schema = {'cls': PostSchema}
    endpoint = {'name': 'post_list'}

ResourceDetail

Instance attributes:

• model (Model): sqlalchemy model
• session (Session): sqlalchemy session instance
• id_field (str): the model identifier attribute name
• url_param_name (str): the name of the URL param in the route to retrieve value from

Class attributs:

• before_update_instance (callable) Optional: additional operations to run before updating an instance in the patch method
• before_delete_instance (callable) Optional: additional operations to run before deleting an instance in the delete method

Example:

from sqlalchemy import NoResultFound
from flask_rest_jsonapi import ResourceList, SqlalchemyDataLayer

from your_project.models import Post
from your_project.schemas import PostSchema
from your_project.extensions import sql_db


def before_update_instance(self, item, data, **view_kwargs):
    """Make additional work before to update your instance:
        - make checks
        - compute an instance attribut
        - or what ever you want.
    """
    data['updated_at'] = datetime.datetime.utcnow()


def before_delete_instance(self, data, **view_kwargs):
    """Make additional work before to delete your instance:
        - make checks
        - or what ever you want.
    """


class PostDetail(ResourceDetail):

    class Meta:
        data_layer = {'cls': SqlalchemyDataLayer,
                      'kwargs': {'session': sql_db.session,
                                 'model': Post,
                                 'id_field': 'post_id',
                                 'url_param_name': 'post_id'},
                      'before_update_instance': before_update_instance,
                      'before_delete_instance': before_delete_instance}

    resource_type = 'post'
    schema = {'cls': PostSchema}

Available opertations

All available operations on SQLAlchemy model fields (depending on the field type) can be used for filtering. See the SQLAlchemy documentation to learn more.

Mongo

A data layer around MongoDB

ResourceList

Instance attributes:

• collection (str): the mongodb collection name
• mongo: the mongodb connector
• model (type): the type of the document

Class attributs:

• get_base_query (callable): a callable to retrieve the base data in get method

Example:

from flask_rest_jsonapi import ResourceList, MongoDataLayer

from your_project.models import Post
from your_project.schemas import PostSchema
from your_project.extensions import mongo


def get_base_query(self, **view_kwargs):
    """Get base data filter
    """
    return {'topic_id': view_kwargs['topic_id']}


class PostList(ResourceList):

    class Meta:
        data_layer = {'cls': MongoDataLayer,
                      'kwargs': {'collection': 'logging',
                                 'model': dict,
                                 'mongo': mongo},
                      'get_base_query': get_base_query}

    resource_type = 'post'
    schema = {'cls': PostSchema}
    endpoint = {'name': 'post_list'}

ResourceDetail

Instance attributes:

• collection (str): the mongodb collection name
• mongo: the mongodb connector
• model (type): the type of the document
• id_field (str): the model identifier attribute name
• url_param_name (str): the name of the URL param in the route to retrieve value from

Example:

from flask_rest_jsonapi import ResourceList, MongoDataLayer

from your_project.models import Post
from your_project.schemas import PostSchema
from your_project.extensions import mongo


class PostDetail(ResourceDetail):

    class Meta:
        data_layer = {'cls': MongoDataLayer,
                      'kwargs': {'collection': 'post',
                                 'mongo': mongo,
                                 'model': dict,
                                 'id_field': 'post_id',
                                 'url_param_name': 'post_id'}}

    resource_type = 'post'
    schema = {'cls': PostSchema}

Available opertations

All available operations on mongodb fields (depending on the field type) can be used for filtering. See the MongoDB documentation to learn more.