Question

My models are as follows (the fields in floor and board are inconsequential and omitted)

class floor(models.Model):

class board(models.Model):

class run(models.Model):
    floor = models.ForeignKey(Floor)
    boards = models.ManyToManyField(Board)

I have a query as follows:

runs = Run.objects.filter(floor=1)

that returns 2 run objects. Each run has a selection of boards.

runs[0].boards

returns a list of related boards. If i make a comprehension as follows:

[run.boards.all() for run in runs]

I get a list of lists like this:

[[1,2,3,4,5], [6,7,8,9,10]]

What is an effective and efficient way to massage the above list into the list below?

[1,2,3,4,5,6,7,8,9,10]

I am hoping for a 1 line solution. Is this possible using methods of the django query set, or is this best accomplished using python?

Answer 1

Simple:

board.objects.filter(run__floor=1)