sqlalchemy IS NOT NULL select

Question

How can I add the filter as in SQL to select values that are NOT NULL from a certain column ?

SELECT * 
FROM table 
WHERE YourColumn IS NOT NULL;

How can I do the same with SQLAlchemy filters?

select = select(table).select_from(table).where(all_filters) 

Answer 1

column_obj != None will produce a IS NOT NULL constraint:

In a column context, produces the clause a != b. If the target is None, produces a IS NOT NULL.

or use is_not()^*:

Implement the IS NOT operator.

Normally, IS NOT is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS NOT may be desirable if comparing to boolean values on certain platforms.

Demo:

>>> from sqlalchemy.sql import column
>>> column('YourColumn') != None
<sqlalchemy.sql.elements.BinaryExpression object at 0x10f81aa90>
>>> print(column('YourColumn') != None)
"YourColumn" IS NOT NULL
>>> column('YourColumn').is_not(None)
<sqlalchemy.sql.elements.BinaryExpression object at 0x11081edf0>
>>> print(column('YourColumn').is_not(None))
"YourColumn" IS NOT NULL

You can't use is not None here, because the is not object identity inequality test can't be overloaded the way != can; you'll just get True instead as a ColumnClause instance is not the same object as the None singleton:

>>> column('YourColumn') is not None
True

---

^*) The method was formerly named isnot() and was renamed in SQLAlchemy 1.4. The old name is still available for backwards compatibility.

Answer 2

Starting in version 0.7.9 you can use the filter operator .isnot instead of comparing constraints, like this:

query.filter(User.name.isnot(None))

This method is only necessary if pep8 is a concern.

source: sqlalchemy documentation

Answer 3

In case anyone else is wondering, you can use is_ to generate foo IS NULL:

>>> from sqlalchemy.sql import column
>>> print(column('foo').is_(None))
foo IS NULL
>>> print(column('foo').isnot(None))
foo IS NOT NULL