Load YAML data fixtures for SQLAlchemy
Project description
Load YAML data fixtures for SQLAlchemy
This package allows you to define some data in YAML and load them into a DB. The yaml data should correspond to SQLAlchemy declarative mappers.
Example:
- User:
- __key__: joey
username: joey
email: joey@example.com
profile:
name: Jeffrey
- __key__: dee
username: deedee
email: deedee@example.com
- Profile:
- user: dee
name: Douglas
- Group:
- name: Ramones
members: [joey.profile, dee.profile]
The root of YAML contains a sequence of mapper names e.g. - User, - Profile etc
The order of these names should follow relationship dependencies
Every name should contain a sequence of instances
Each instance is a mapping of attribute -> value
the attributes are taken from the mapper __init__() (usually an attributes maps to a column)
The special field __key__ can be used to identify this instnace in a relationship reference e.g. The Profile.user
Note that any __key__ MUST be globally unique
In a to-one relationship the data can be directly nested in the parent data definition
References can access attributes using a dot notation, e.g. joey.profile
to-many relationships can be added as a list of references
The mapper definition for this example is in the test file.
Installation
pip install sqla-yaml-fixtures
API
This module expose a single function load(ModelBase, session, fixture_text, loader=None)
Where:
ModelBase is SQLAlchemy declarative base
session is SQLAlchemy session
fixture_text is a string containg the YAML fixtures
from sqlalchemy import create_engine
from sqlalchemy import Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import Session
import sqla_yaml_fixtures
BaseModel = declarative_base()
class User(BaseModel):
__tablename__ = 'user'
id = Column(Integer, primary_key=True)
username = Column(String(150), nullable=False, unique=True)
email = Column(String(254), unique=True)
def main():
engine = create_engine('sqlite://')
BaseModel.metadata.create_all(engine)
connection = engine.connect()
session = Session(bind=connection)
fixture = """
- User:
- username: deedee
email: deedee@example.com
- username: joey
email: joey@example.commit
"""
sqla_yaml_fixtures.load(BaseModel, session, fixture)
print('\n'.join(u.username for u in session.query(User).all()))
if __name__ == '__main__':
main()
Note: the load() function performs a session.commit().
load() returns an instance of Store. Using this object get() method you can passing a key as argument you get a reference to the object added into the database. This is useful to easily get attributes that are generated by the database.
store = sqla_yaml_fixtures.load(BaseModel, session, fixture)
my_obj = store.get('dee')
print('Created object id: {}'.format(my_obj.id))
Command Line
For basic usage there is also command line. Example:
$ python -m sqla_yaml_fixtures --db-url sqlite:///dev.db --db-base mypkg.models:Base --reset-db --alembic-stamp fixture.yaml
All available options:
$ python -m sqla_yaml_fixtures --help usage: sqla_yaml_fixtures [-h] --db-base DB_BASE --db-url DB_URL [--yes] [--reset-db] [--alembic-stamp] [--jinja2] FILE [FILE ...] load fixtures from yaml file into DB positional arguments: FILE YAML file with DB fixtures optional arguments: -h, --help show this help message and exit --db-base DB_BASE SQLAlchemy Base class with schema metadata in the format my_package.my_module:MyClass --db-url DB_URL Database URL in the format dialect+driver://username:password@host:port/database --yes Do NOT ask for confirmation before applying fixtures --reset-db Drop DB schema and data and re-create schema before loading fixtures --alembic-stamp Perform `alembic stamp head` --jinja2 load fixture files as jinja2 templates
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