Re: Help me develop a Job Tracker (?)

On Fri, Jul 3, 2015 at 2:50 AM, Softeisbieger <j.kitschke@gmx.de> wrote:
> Thanks for your input! Indeed, a linear pipeline should be sufficient. What
> do you think of my idea of organizing this in two database tables? One table
> models a work flow. A work flow points to the currently active task in
> another table. Each task has information about its predecessor / successor.
> In principle like a doubly-linked list. This solution feels a bit brittle /
> hacked to me. Again, my reason is, I want to store all the work flows with
> this standard interface. Also, users can easily create new work flows with
> any number of steps. Maybe there is a better way?


i don't think a linked list is appropriate for databases. the
simplest design would be: a Workflow model to identify it (with id,
name, creator, that kind of things), and a Step model that 'belongs'
to the Workflow something like this:

class Workflow(models.model):
name = models.charfield()

class Step(models.model):
workflow = models.ForeignKeyField(Workflow)
name = models.charfield()
order = models.SmallIntegerField()
taskdescriiption = models.TextField()

class Meta:
ordering = ['workflow','order']

def previous(self):
return self.workflow.step_set.filter(order_lt=self.order)[-1]

def next(self):
return self.workflow.step_set.filter(order_gt=self.order)[0]


those two models keep the definition of a workflow. then, define the
'working' models, one for a whole project, and other for each task to
perform:

class Project(models.model):
name = models.charfield()
workflow = models.ForeignKeyField(Workflow)
responsible = models.ForeignKeyField(User)
deadline = models.DatetimeField()

def started_tasks(self):
return self.task_set.filter(start__isnull=False)

def finished_tasks(self):
return self.task_set.filter(finish__isnull=False)

def in_process_tasks(self):
return self.task_set.filter(start__isnull=False, finish__isnull=True)

def finished(self):
return self.started_tasks.exist() and not self.in_process_task.exist()

class Task(models.model):
project = models.ForeignKeyField(Task)
step = models.ForeignKeyField(Step)
deadline = models.DatetimeField()
assigned_to = models.ForeignKeyField(User, blank=True, null=True)
start = models.DatetimeField(blank=True, null=True)
finish = models.DatetimeField(blank=True, null=True)


in most cases, it's better not to have a 'current task' pointer. just
some tasks that have been started but not finished(yet). it's up to
you to decide if it's appropriate to have more than one task in
process for a given project, or if it's valid to start a task before
some of the previous tasks.

usually it's also nice to add action methods to some models, maybe a
project.start(user) that creates the first task and starts it, and a
project.next(user) that finishes a task and creates/starts the next
one (if there's any more step(s)).

--
Javier

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