Magic schemas

[guiferviz]

Using the power of varname and a class column like the following:

from varname import varname


class column(str):
    def __new__(cls, dtype: type = str, alias: str = None, key: bool = False):
        if alias is None:
            alias = str(varname())
        return str.__new__(cls, alias)

    def __init__(self, dtype: type = str, alias: str = None, key: bool = False):
        self.dtype = dtype
        self.key = key

We can define schemas in nested classes inside the table. For example:

class MyTable(Table):
    class schema:
        id = column(int)
        name = column()

See some examples of tests that are all passing:

from deleteme2 import column


def test_column_with_type():
    class schema:
        id = column(int)

    assert schema.id == "id"
    assert schema.id.dtype == int
    assert schema.id.key == False


def test_column_with_alias():
    class schema:
        id = column(int, alias="identity")

    assert schema.id == "identity"
    assert schema.id.dtype == int
    assert schema.id.key == False


def test_column_with_key():
    class schema:
        id = column(key=True)

    assert schema.id == "id"
    assert schema.id.dtype == str
    assert schema.id.key == True


def test_column_default_params():
    class schema:
        id = column()

    assert schema.id == "id"
    assert schema.id.dtype == str
    assert schema.id.key == False


def test_nested_schema():
    class schema:
        id = column()
        class nested:
            id_nested = column()

    assert schema.id == "id"
    assert schema.nested.__name__ == "nested"
    assert schema.nested.id_nested == "id_nested"