How to iterate over nested dictionaries in django templates - django

Question

I'm not sure the most efficient way to iterate over my nested dictionaries to print a matrix of the total and good values for every fruit for each date. Take for instance the two lists and dictionary below:
fruits = ['apples','oranges','bananas']
harvest_dates = ['2011-07-23','2011-07-22','2011-07-21']
harvest_data = {
'apples': {
'2011-07-23': {
'total': 100,
'good': 80},
'2011-07-22': {
'total': 97,
'good': 92},
'2011-07-21': {
'total': 90,
'good': 85}
},
'oranges': {
'2011-07-23': {
'total': 86,
'good': 82},
'2011-07-22': {
'total': 90,
'good': 75},
'2011-07-21': {
'total': 92,
'good': 92}
},
'bananas': {
'2011-07-23': {
'total': 10,
'good': 9},
'2011-07-22': {
'total': 12,
'good': 11},
'2011-07-21': {
'total': 9,
'good': 9}
}
}
I can easily do this in python:
for fruit in fruits:
for day in harvest_dates:
print "harvest: %s" % harvest_data[fruit][day]['total']
print "good crop: %s" % harvest_data[fruit][day]['good']
But I don't know how to access this data in django templates. I had been trying something such as:
{% for fruit in fruits %}
...
{% for day in harvest_dates %}
...
{{ harvest_data.fruit.day.total }}
{{ harvest_data.fruit.day.good }}
...
{% endfor %}
{% endfor %}
But it's simply not working.
{% for fruit in fruits %}
{{ harvest_data.fruit }} <--- this does not exist
{{ harvest_data[fruit] }} <--- this does not work
{% endfor %}
I'm a complete amateur and I'm probably going about this all wrong, but I've Google'd quite a bit and it's not clear to me what the best approach to getting the data I want is.

Answer 1

Since you're familiar with python, the following is logically how you would want to iterate through your dictionary in a Django template:
for key,value in harvest_data.items():
... print key
... for key2,value2 in value.items():
... print key2
... for key3,value3 in value2.items():
... print "%s:%s"%(key3,value3)
In your template, this translates as follows:
{% for key, value in harvest_data.items %}
{{ key }} <br>
{% for key2,value2 in value.items %}
{{ key2 }} <br>
{% for key3, value3 in value2.items %}
{{ key3 }}:{{ value3 }} <br>
{% endfor %}
{% endfor %}
{% endfor %}
The Django docs actually briefly include an example of how to iterate through dictionaries when describing how the for template tag works:
https://docs.djangoproject.com/en/dev/ref/templates/builtins/#for

Answer 2

as rolling stone says thats the way to iterate over dictionaries in templates, i would only change the key, value keywords for different keywords in every iteration like this:
{% for key, value in harvest_data.items %}
{{ key }} <br>
{% for key2,value2 in value.items %}
{{ key2 }} <br>
{% for key3, value3 in value2.items %}
{{ key3 }}:{{ value3 }} <br>
{% endfor %}
{% endfor %}
{% endfor %}
just for the sake of clarity :)
And if you want to line up your values i would suggest you use another data structure where you can sort by date, for example a something like this:
{ 'oranges' : [(date1, value1), (date2,value2)] ...}
Try to do the least possible operations in your templates, so dont do a sort or nested if's if you dont have to

Answer 3

Really old question, but I will add my 1.5c.
This is a good use case of the regroup tag (https://docs.djangoproject.com/en/1.9/ref/templates/builtins/#regroup) and a bit of data refactoring:
Have your data as a simple list of data points:
harvest_data = [
{'fruits': 'apples', 'date': '2011-07-23', 'total': 100, 'good': 80},
# ...
]
In your template, group by the chosen dimension(s):
{% regroup harvest_data by fruits as data_by_fruits %}
{% for data in data_by_fruits %}
<h1>{{ data.grouper }}</h1> # 'apples'
{% regroup data.list by date as data_by_fruits_date %}
{% for data_1 in data_by_fruits_date %}
<h2>{{ data_1.grouper }}</h2> # '2011-07-23'
{% for datapoint in data_1.list %}
total: {{ datapoint.total }} <br/>
good: {{ datapoint.good }} <br/>
{% endfor %}
{% endfor %}
{% endfor %}