Schema Customization

Generate with a New Token

---

You can crate a schema containing the specified table data with a new token using new(...) methods.

>>> from t4_devkit.schema import Attribute
>>> from t4_devkit.common.serialize import serialize_dataclass
>>>
>>> # schema data except of the unique identifier token
>>> data = {
...     "name": "foo",
...     "description": "this is re-generated attribute."
... }
>>>
>>> attr1 = Attribute.new(data)
>>>
>>> # Also, it allows us to create a copy of the existing table data with a new token
>>> serialized = serialize_dataclass(attr1)
>>> attr2 = Attribute.new(serialized)
>>>
>>> attr1.token != attr2.token
True
>>> attr1
Attribute(token='b08701e5095fbd12a45e7f51b85ffc08', name='foo', description='this is re-generated attribute.')
>>> attr2
Attribute(token='f40e605870aa29b1473ca6e65255c45e', name='foo', description='this is re-generated attribute.')

Customize Schema Classes

---

You can customize schema classes on your own code, if you need for some reasons.

For example, you might meet the error because of missing some mandatory fields but it is OK whatever the actual value is.

In here, let's define a custom Attribute class, called CustomAttribute, in your workspace. This class suppresses runtime exception caused by missing description in attribute.json.

Now you have the following workspace structure:

my_package
├── src
│   ├── __init__.py
│   ├── custom_schema.py
│   └── main.py
└── pyproject.toml

By editing custom_schema.py, you can define CustomAttribute overwriting Attribute as follows:

custom_schema.py

from __future__ import annotations

from attrs import define, field

from t4_devkit.schema import SCHEMAS, SchemaName, SchemaBase
from t4_devkit.common.io import load_json

__all__ = ["CustomAttribute"]


@define(slots=False)
@SCHEMAS.register(SchemaName.ATTRIBUTE, force=True)
class CustomAttribute(SchemaBase):
    """Custom Attribute class ignoring if there is no `description` field.
    Note that `description` field is mandatory in the original `Attribute` class.

    `@SCHEMAS.register(SchemaName.ATTRIBUTE, force=True)` performs that
    it forces to update the attribute table in the schema registry.
    """

    name: str
    description: str | None = field(default=None)

Note that CustomAttribute should be imported before instantiating Tier4 class. Then modify __init__.py in order to import it automatically:

__init__.py

from .custom_attribute import * # noqa