[Fixed]-How to call a model method, using the object as parameter in Django?

When you write a model method you pass on self as parameter, which obviously refers to instance itself. Change your model method to something like this

class Task(models.Model):
    fields
    def is_finished(self):
        return appropriate boolean from here

Now in your template you can use this simply as {{ task.is_finished }}. Notice that I am not passing any id as a parameter. This is because, when writing a model method you pass self as parameter which refers to instance on which method is being called.

I hope this makes sense to you and helps you understand model methods in a simple way.

I don’t fully understand your question, why can’t you just sent in task_id as a parameter?

class Task(models.Model):
...
def check_if_finished(self, task_id):
    resp = requests.get(
     'http://my.rest.api/tasks/view/{}'.format(task_id))
    resp_data = resp.json()
    resp_finished = resp_data['task']['started_on']
    if resp_finished is None:
        return False
    else:
        return resp_finished

then call it anytime:

{{ task.check_if_finished(task.task_id) }}

Could also make task_id an optional parameter.

def check_if_finished(self, task_id=None):
    task_id = task_id or self.task_id   
    resp = requests.get...

I’m not sure why you wouldn’t want to use the task_id on the instance though. If you never will then maybe it should be a static method?

@staticmethod
def check_if_finished(cls, task_id): 
    ...

I don’t think Django models prevent any of these options. Hopefully something there was helpful, else I need a bit more information and what you are trying to accomplish.

Edit: Django templates don’t allow calling function/methods with arguments. You need to create a custom template tag or just call the function in the view and send the result to the template. See previous question.