How do I read a nested dictionary in a Django template?

Question

I am trying to access the following data structure inside a template in Django. But its too difficult for me too figure out how.

{ Day1 : { Room1 : [(datetime.date(), (totalTime1, Flag1)),
                    (datetime.date(), (totalTime2, Flag2)),
                    (datetime.date(), (totalTime3, Flag3)),
                    (datetime.date(), (totalTime4, Flag4))],

           Room2 : [(datetime.date(), (totalTime1, Flag1)),
                    (datetime.date(), (totalTime2, Flag2)),
                    (datetime.date(), (totalTime3, Flag3)),
                    (datetime.date(), (totalTime4, Flag4))],

           Room3 : [(datetime.date(), (totalTime1, Flag1)),
                    (datetime.date(), (totalTime2, Flag2)),
                    (datetime.date(), (totalTime3, Flag3)),
                    (datetime.date(), (totalTime4, Flag4))] },

 Day2 : {  Room1 : [(datetime.date(), (totalTime1, Flag1)),
                    (datetime.date(), (totalTime2, Flag2)),
                    (datetime.date(), (totalTime3, Flag3)),
                    (datetime.date(), (totalTime4, Flag4))],

           Room2 : [(datetime.date(), (totalTime1, Flag1)),
                    (datetime.date(), (totalTime2, Flag2)),
                    (datetime.date(), (totalTime3, Flag3)),
                    (datetime.date(), (totalTime4, Flag4))],

           Room3 : [(datetime.date(), (totalTime1, Flag1)),
                    (datetime.date(), (totalTime2, Flag2)),
                    (datetime.date(), (totalTime3, Flag3)),
                    (datetime.date(), (totalTime4, Flag4))] } }

Probably its a very complex data structure, but I am sorry about it. I couldnt break it up. My choice is limited. I want to access each element in a single loop. How may I do it?

Edit : I want to access the elements from a django template.

Answer 1

It can't be done in a single loop, but you can do it with some nesting:

{% for day, rooms in mydict.items %}
  {% for room, dates_and_flags in rooms.items %}
    {% for date, time_and_flags in dates_and_flags %}
        {{ date }}:{{ time_and_flags }}
    {% endfor %}
  {% endfor %}
{% endfor %}

Because time_and_flags is a tuple, you can access the time using time_and_flags.0 and the flags with time_and_flags.1.

Answer 2

I was able to do it with a single loop - although maybe I misunderstood the previous answers or initial question. Regardless, this might be helpful to anyone else looking into working with nested dictionaries in Django

Combine

• the .items() method to loop over the dictionary in Django
• the .value syntax for the attribute lookup

Your example dictionary wasn't quite a dictionary, so as another example

grades_dict = {'Math': {'grade': 78, 'grade_date': '2016-05-15'},
'Reading': {'grade': 83, 'grade_date': '2016-08-16'},
'Science': {'grade': 98, 'grade_date': '2016-08-16'},
'Social Studies': {'grade': 62, 'grade_date': '2016-05-15'}}

in django template html

{% for key, value in grades_dict.items %}
    <p>Grade for {{key}}: {{value.grade}}. </p>
    <p>Last entered on {{value.most_recent_grade_date}}</p>
{% endfor %}

results in

Grade for Social Studies: 62.

Last entered on 2016-05-15

Grade for Science: 98.

Last entered on 2016-08-16

Grade for Reading: 83.

Last entered on 2016-08-16

Grade for Math: 78.

Last entered on 2016-05-15

Answer 3

This is a generator function that will return each row in a loop:

def next_row(data):
    for day,rooms in data.iteritems():
        for room,times in rooms.iteritems():
            for time in times:
                yield (day, room, time)

Use it like this:

for row in next_row(data):
    # do something with row

Answer 4

Your question doesn't exactly say what do you want to do with your nested dictionnary, but here's a wild guess:

for day,rooms in days.iteritems():
    print "Rooms for day {}:".format(day)
    for room, times in rooms.iteritems():
        print "  . Room {}".format(room)
        for t in times:
            print "Date : {} | Total time : {} | Flag : {}".format(t[0], t[1][0], t[1][1])

Answer 5

If you want a certain value, you can access it like this.

{{ Day1.Room1 }}

Check this link https://docs.djangoproject.com/en/4.0/ref/templates/language/#variables