SQLAlchemy - “Dynamic Filter”

Question

I have just started using SQLAlchemy. I decided to use it because I was using a lot of string expression in the middle of my sqlite queries.

So, that is my problem.

Answer 1

I assume you are using the ORM.

in that case, the filter function returns a query object. You can conditionaly build the query by doing something like

query = Session.query(schema.Object).filter_by(attribute=value)
if condition:
    query = query.filter_by(condition_attr=condition_val)
if another_condition:
    query = query.filter_by(another=another_val)

#then finally execute it

results = query.all()

Answer 2

The function filter(*criterion) means you can use tuple as it's argument, @Wolph has detail here: SQLALchemy dynamic filter_by for detail

Answer 3

if we speak of SQLAlchemy core, there is another way:

from sqlalchemy import and_


filters = [table.c.col1 == filter1, table.c.col2 > filter2]
query = table.select().where(and_(*filters))

If you're trying to filter based on incoming form criteria:

form = request.form.to_dict()
filters = []
for col in form:
    sqlalchemybinaryexpression = (getattr(MODEL, col) == form[col])
    filters.append(sqlalchemybinaryexpression)
query = table.select().where(and_(*filters))

Where MODEL is your SQLAlchemy Model