sqlalchemyseed

Sqlalchemy seeder that supports nested relationships.

Installation

Default installation

pip install sqlalchemyseed

When using yaml to loading entities from yaml files. Execute this command to install necessary dependencies

pip install sqlalchemyseed[yaml]

Dependencies

Required

• SQAlchemy>=1.4.0

Optional

• PyYAML>=5.4.0

Getting Started

# main.py
from sqlalchemyseed import load_entities_from_json, Seeder
from db import session

# load entities
entities = load_entities_from_json('tests/test_data.json')

# Initializing Seeder
seeder = Seeder()  # or Seeder(session)

# Seeding
seeder.session = session  # assign session if no session assigned before seeding
seeder.seed(entities)

# Committing
session.commit()  # or seeder.session.commit()

Seeder vs. HybridSeeder

Features & Options	Seeder	HybridSeeder
Support model and data keys	✔️	✔️
Support model and filter keys	❌	✔️
Optional argument add_to_session=False in the seed method	✔️	❌
Assign existing objects from session or db to a relationship attribute	❌	✔️

When to use HybridSeeder and 'filter' key field?

Assuming that Child(age=5) exists in the database or session, then we should use filter instead of data, the values of filter will query from the database or session, and assign it to the Parent.child

from sqlalchemyseed import HybridSeeder
from db import session

data = {
    "model": "models.Parent",
    "data": {
        "!child": {
            "model": "models.Child",
            "filter": {
                "age": 5
            }
        }
    }
}


# When seeding instances that has 'filter' key, then use HybridSeeder, otherwise use Seeder.
seeder = HybridSeeder(session)
seeder.seed(data)

session.commit() # or seeder.sesssion.commit()

Relationships

In adding a relationship attribute, add prefix ! to the key in order to identify it.

Referencing relationship object or a foreign key

If your class don't have a relationship attribute but instead a foreign key attribute you can use it the same as how you did it on a relationship attribute

from sqlalchemyseed import HybridSeeder
from db import session

instance = [
    {
        'model': 'tests.models.Company',
        'data': {'name': 'MyCompany'}
    },
    {
        'model': 'tests.models.Employee',
        'data':[  
            {
                'name': 'John Smith',
                # foreign key attribute
                '!company_id': {
                    'model': 'tests.models.Company',
                    'filter': {
                        'name': 'MyCompany'
                    }
                }
            },
            {
                'name': 'Juan Dela Cruz',
                # relationship attribute
                '!company': {
                    'model': 'tests.models.Company',
                    'filter': {
                        'name': 'MyCompany'
                    }
            }
        ]
    }
]

seeder = HybridSeeder(session)
seeder.seed(instance)

No Relationship

// test_data.json
[
    {
        "model": "models.Person",
        "data": {
            "name": "You",
            "age": 18
        }
    },
    // when you have two or more objects of the same model, you can
    {
        "model": "models.Person",
        "data": [
            {
                "name": "You",
                "age": 18
            },
            {
                "name": "Still You But Older",
                "age": 40
            }
        ]
    }
]

One to One

// test_data.json
[
    {
        "model": "models.Person",
        "data": {
            "name": "John",
            "age": 18,
            // creates a job object
            "!job": {
                "model": "models.Job",
                "data": {
                    "job_name": "Programmer",
                }
            }
        }
    },
    // or this, if you want to add relationship that exists
    // in your database use 'filter' instead of 'obj'
    {
        "model": "models.Person",
        "data": {
            "name": "Jeniffer",
            "age": 18,
            "!job": {
                "model": "models.Job",
                "filter": {
                    "job_name": "Programmer",
                }
            }
        }
    }
]

One to Many

//test_data.json
[
    {
        "model": "models.Person",
        "data": {
            "name": "John",
            "age": 18,
            "!items": [
                {
                    "model": "models.Item",
                    "data": {
                        "name": "Pencil"
                    }
                },
                {
                    "model": "models.Item",
                    "data": {
                        "name": "Eraser"
                    }
                }
            ]
        }
    }
]

Example of Nested Relationships

{
    "model": "models.Parent",
    "data": {
        "name": "John Smith",
        "!children": [
            {
                "model": "models.Child",
                "data": {
                    "name": "Mark Smith",
                    "!children": [
                        {
                            "model": "models.GrandChild",
                            "data": {
                                "name": "Alice Smith"
                            }
                        }
                    ]
                }
            }
        ]
    }
}