How to mock .query.filter_by() in Flask-SqlAlchemy

Question

In brief

When testing a model class in Flask-SqlAlchemy, how can we mock the method .query.filter_by() so as to return the list of mocked model object

Answer 1

Just a sum-up from Martijn Pieters answer

Target

• We want to mock .query.filter_by().all() result e.g. SomeModel.query.filter_by().all()

Code 01

@patch('flask_sqlalchemy._QueryProperty.__get__')
def test (
  self,
  queryMOCK,
):

  #setup
  queryMOCK\
    .return_value.filter_by\
    .return_value.all\
    .return_value = [1,22] #empty list of current product_id

  #get actual
  modelObj = SomeModel.query.filter_by().all()
  print(modelObj)

Code 02 - similar as above and using with

def test(self):
  with patch('flask_sqlalchemy._QueryProperty.__get__') as queryMOCK      #setup
    queryMOCK\
      .return_value.filter_by\
      .return_value.all\
      .return_value = [1,22] #empty list of current product_id

    #get actual
    modelObj = SomeModel.query.filter_by().all()
    print(modelObj)