Flow

For linear (non-branching) sections, flow, the order of questions, is solely controlled by the position-field in Sections and Questions.

For optional and branching sections, the ExplicitBranch model comes into play.

Visualizing flow

With graphviz, the devfixtures, and the dependencies in requirements/dev.txt installed, it is possible to generate a flow chart for a section.

Start up a python shell with:

python manage.py shell

Inside the shell, try:

from easydmp.dmpt.models import Template, Section
t = Template_objects.get(id=1)
s = t.sections.all()[0]
s.view_dotsource('pdf')

A section with no questions will look like two double circles.

A linear section will have a start-node in a double-circle, an arrow going to the first question, another from the first question to the second, all the way to the last, which will have an arrow to an end-node in a double-circle. All the arrows will be marked by ->, because thet marks movement through the position-field.

In a branching section, multiple arrows can both eneter and leave a question, and the markers on the arrows will be one of:

->

for movement through position.

=>

for movement through position from a question that has a node, usually the last node in a branch.

a string

for an edge with a condition. This is only for question with CannedAnswers.

empty

for an edge without a condition, ususally due to an edge without a CannedAnswer.

Too many of the last type is usually a sign that the graph is too complex.

There should be no loops.