import abc
import datetime
import typing
from asyncqlio.exc import DatabaseException
from asyncqlio.orm import operators as md_operators
from asyncqlio.orm.schema import column as md_column, table as md_table
[docs]class ColumnValidationError(DatabaseException):
"""
Raised when a column fails validation.
"""
[docs]class ColumnType(abc.ABC):
"""
Implements some underlying mechanisms for a :class:`.Column`.
The only method that is required to be implemented on children is :meth:`.ColumnType.sql` -
which is used in CREATE TABLE declarations, etc. :meth:`.ColumnType.on_set`,
:meth:`.ColumnType.on_get` and so on are not required to be implemented - the defaults will
work fine.
The ColumnType is responsible for actually loading the data from the row's internal storage
and to the user code.
.. code-block:: python3
# we hate fun
def on_get(self, row, column):
return "lol"
...
# row is a random row object
# load the `fun` column which has this weird type
value = row.fun
print(value) # "lol", regardless of what was stored in the database.
Accordingly, it is also responsible for storing the data into the row's internal storage.
.. code-block:: python3
def on_set(*args, **kwargs):
return None
row.not_fun = 1
print(row.not_fun) # None - no value was stored in the row
To actually insert a value into the row's storage table, use :meth:`.ColumnType.store_value`.
Correspondingly, loading a value from the row's storage table can be achieved with
:meth:`.ColumnType.load_value`. These functions should be used, as they are guarenteed to work
across all versions.
Columns will proxy bad attribute accesses from the Column object to this type object - meaning
types can implement custom operators, if applicable.
.. code-block:: python3
class User(Table):
id = Column(MyWeirdType())
...
# MyWeirdType implements `.contains`
# the contains call is proxied to (MyWeirdType instance).contains("heck")
q = await sess.select(User).where(User.id.contains("heck")).first()
"""
__slots__ = ("column",)
def __init__(self):
#: The column this type object is associated with.
self.column = None # type: md_column.Column
[docs] @abc.abstractmethod
def sql(self) -> str:
"""
:return: The str SQL name of this type.
"""
[docs] def validate_set(self, row: 'md_table.Table',
value: typing.Any) -> bool:
"""
Validates that the item being set is valid.
This is called by the default ``on_set``.
:param row: The row being set.
:param value: The value to set.
:return: A bool indicating if this is valid or not.
"""
return True
[docs] def store_value(self, row: 'md_table.Table',
value: typing.Any):
"""
Stores a value in the row's storage table.
This is for internal usage only.
:param row: The row to store in.
:param value: The value to store in the row.
"""
row.store_column_value(self.column, value)
[docs] def on_set(self, row: 'md_table.Table', value: typing.Any) -> typing.Any:
"""
Called when a value is a set on this column.
This is the default method - it will call :meth:`.ColumnType.validate_set` to validate the
type before storing it. This is useful for simple column types.
:param row: The row this value is being set on.
:param value: The value being set.
"""
if value is not None:
valid = self.validate_set(row, value)
if not valid:
raise ColumnValidationError("Value {} failed to validate in type {}"
.format(value, type(self).__name__))
self.store_value(row, value)
[docs] def on_get(self, row: 'md_table.Table') -> typing.Any:
"""
Called when a value is retrieved from this column.
:param row: The row that is being retrieved.
:return: The value of the row's internal storage.
"""
return row.get_column_value(self.column)
[docs] @classmethod
def create_default(cls) -> 'ColumnType':
"""
Creates the default object for this table in the event that a type is passed to a column,
instead of an instance.
"""
return cls()
# Some methods for base types
[docs] def in_(self, *args) -> 'md_operators.In':
"""
Returns an IN operator, checking if a value in this column is in a tuple of items.
:param args: The items to check.
"""
if len(args) <= 0:
raise ValueError("Must provide at least one argument to in_")
return md_operators.In(self.column, args)
[docs]class String(ColumnType):
"""
Represents a VARCHAR() type.
"""
def __init__(self, size: int = -1):
super().__init__()
#: The max size of this String.
self.size = size
def sql(self):
# return max if theres no size
# since we want to create an unbounded varchar
if self.size >= 0:
return "VARCHAR({})".format(self.size)
else:
return "VARCHAR"
def validate_set(self, row, value: typing.Any):
if self.size < 0:
return True
if len(value) > self.size:
raise ColumnValidationError("Value {} is more than {} chars long".format(value,
self.size))
return True
[docs] def like(self, other: str) -> 'md_operators.Like':
"""
Returns a LIKE operator, checking if this column is LIKE another string.
:param other: The other string to check.
"""
return md_operators.Like(self.column, other)
[docs] def ilike(self, other: str) -> 'typing.Union[md_operators.ILike, md_operators.HackyILike]':
"""
Returns an ILIKE operator, checking if this column is case-insensitive LIKE another string.
.. warning::
This is not supported in all DB backends.
:param other: The other string to check.
"""
if self.column.table._bind.dialect.has_ilike:
return md_operators.ILike(self.column, other)
else:
return md_operators.HackyILike(self.column, other)
[docs]class Text(String):
"""
Represents a TEXT type.
TEXT type columns are very similar to String type objects, except that they have no size limit.
.. note::
This is preferable to the String type in some databases.
.. warning::
This is deprecated in MSSQL.
"""
def __init__(self):
# unlimited size
super().__init__(size=-1)
def sql(self):
return "TEXT"
[docs]class Boolean(ColumnType):
"""
Represents a BOOL type.
"""
def sql(self):
return "BOOLEAN"
def validate_set(self, row: 'md_table.Table', value: typing.Any):
return value in [True, False]
[docs]class Integer(ColumnType):
"""
Represents an INTEGER type.
.. warning::
This represents a 32-bit integer (2**31-1 to -2**32)
"""
def sql(self):
return "INTEGER"
[docs] def validate_set(self, row, value: typing.Any):
"""
Checks if this int is in range for the type.
"""
return -2147483648 < value < 2147483647
def on_set(self, row, value: typing.Any):
if not isinstance(value, int):
raise ColumnValidationError("Value {} is not an int".format(value))
return super().on_set(row, value)
[docs]class SmallInt(Integer):
"""
Represents a SMALLINT type.
"""
def sql(self):
return "SMALLINT"
def validate_set(self, row, value: typing.Any):
return -32768 < value < 32767
[docs]class BigInt(Integer):
"""
Represents a BIGINT type.
"""
def sql(self):
return "BIGINT"
def validate_set(self, row, value):
return -9223372036854775808 < value < 9223372036854775807
[docs]class Timestamp(ColumnType):
"""
Represents a TIMESTAMP type.
"""
def sql(self):
return "TIMESTAMP"
def validate_set(self, row, value):
return isinstance(value, datetime.datetime)