attribute access and setting for pydantic_model uned the hood

orm/fields.py

@@ -0,0 +1,73 @@
+import sqlalchemy
+
+from orm.exceptions import ModelDefinitionError
+
+
+class BaseField:
+    __type__ = None
+
+    def __init__(self, *args, **kwargs):
+        name = kwargs.pop('name', None)
+        args = list(args)
+        if args:
+            if isinstance(args[0], str):
+                if name is not None:
+                    raise ModelDefinitionError(
+                        'Column name cannot be passed positionally and as a keyword.'
+                    )
+                name = args.pop(0)
+
+        self.name = name
+        self.primary_key = kwargs.pop('primary_key', False)
+        self.autoincrement = kwargs.pop('autoincrement', 'auto')
+
+        self.nullable = kwargs.pop('nullable', not self.primary_key)
+        self.default = kwargs.pop('default', None)
+        self.server_default = kwargs.pop('server_default', None)
+
+        self.index = kwargs.pop('index', None)
+        self.unique = kwargs.pop('unique', None)
+
+    def get_column(self, name=None) -> sqlalchemy.Column:
+        name = self.name or name
+        constraints = self.get_constraints()
+        return sqlalchemy.Column(
+            name,
+            self.get_column_type(),
+            *constraints,
+            primary_key=self.primary_key,
+            autoincrement=self.autoincrement,
+            nullable=self.nullable,
+            index=self.index,
+            unique=self.unique,
+            default=self.default,
+            server_default=self.server_default
+        )
+
+    def get_column_type(self) -> sqlalchemy.types.TypeEngine:
+        raise NotImplementedError()  # pragma: no cover
+
+    def get_constraints(self):
+        return []
+
+
+class String(BaseField):
+    __type__ = str
+
+    def __init__(self, *args, **kwargs):
+        assert 'length' in kwargs, 'length is required'
+        self.length = kwargs.pop('length')
+        super().__init__(*args, **kwargs)
+
+    def get_column_type(self):
+        return sqlalchemy.String(self.length)
+
+
+class Integer(BaseField):
+    __type__ = int
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+    def get_column_type(self):
+        return sqlalchemy.Integer()