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Django: Converting an entire set of a Model's objects into a single dictionary

Posted by: admin November 30, 2017 Leave a comment

Questions:

If you came here from Google looking for model to dict, skip my question, and just jump down to the first answer. My question will only confuse you.

Is there a good way in Django to entire set of a Model’s objects into a single dictionary? I mean, like this:

class DictModel(models.Model):
    key = models.CharField(20)
    value = models.CharField(200)


DictModel.objects.all().to_dict()

… with the result being a dictionary with the key/value pairs made up of records in the Model? Has anyone else seen this as being useful for them?

Thanks.

Update
I just wanted to add is that my ultimate goal is to be able to do a simple variable lookup inside a Template. Something like:

{{ DictModel.exampleKey }}

With a result of DictModel.objects.get(key__exact=exampleKey).value

Overall, though, you guys have really surprised me with how helpful allof your responses are, and how different the ways to approach it can be. Thanks a lot.

Update October 2011:
This question is the top result if you Google “django model_to_dict”, which is actually pretty awful given that it solves a different problem than what I was asking.

What I wanted was to be able to map all of the instances in a queryset into a single dictionary with a specified model field as the key.
model_to_dict, on the other hand converts a single model instance into a dictionary.

Now, my needs at the time were pretty darn specific, and probably extremely rare (I can’t even remember the project I needed it for, or why). So I would be pretty surprised that anyone looking for information about model_to_dict is going to find my question actually useful. Sorry.

model_to_dict seems to be a much more common usage case than I had.

Update Dec 2011:
I changed the title to hopefully better reflect my original intent.

Answers:

Does this need to create an actual dict? could you get by with only something that looked like a dict?

class DictModelAdaptor():
    def __init__(self, model):
        self.model = model

    def __getitem__(self, key):
        return self.model.objects.get(key=key)

    def __setitem__(self, key, item):
        pair = self.model()
        pair.key = key
        pair.value = item
        pair.save()

    def __contains__(self, key):
        ...

You could then wrap a model in this way:

modelDict = DictModelAdaptor(DictModel)
modelDict["name"] = "Bob Jones"

etc…

Questions:
Answers:

You can also rely on django code already written ;).

from django.forms.models import model_to_dict
model_to_dict(instance, fields=[], exclude=[])

Questions:
Answers:

You are looking for the Values member of QuerySet which allows you to get a list of dictionaries from your query

Returns a ValuesQuerySet — a QuerySet
that evaluates to a list of
dictionaries instead of model-instance
objects. Each of those dictionaries represents
an object, with the keys corresponding
to the attribute names of model
objects.

>>> Blog.objects.values()
[{'id': 1, 'name': 'Beatles Blog', 'tagline': 'All the latest Beatles news.'}],
>>> Blog.objects.values('id', 'name')
[{'id': 1, 'name': 'Beatles Blog'}]

Questions:
Answers:

You want the in_bulk queryset method which, according to the docs:

Takes a list of primary-key values and
returns a dictionary mapping each
primary-key value to an instance of
the object with the given ID.

It takes a list of IDs, so you’ll need to get that first via the values_list method:

ids = MyModel.objects.values_list('id', flat=True)
model_dict = MyModel.objects.in_bulk(ids)

Questions:
Answers:

You can use the python serializer:

from django.core import serializers
data = serializers.serialize('python', DictModel.objects.all())

Questions:
Answers:

dict((x.name, getattr(o, x.name)) for x in o._meta.fields)

Questions:
Answers:

use

dict(((m.key, m.value) for m in DictModel.objects.all())

As suggested by Tom Leys, we do not need to get whole object, we can get only those values we need e.g.

dict(((m['key'], m['value']) for m in DictModel.objects.values('key', 'value')))

and if you need all values, it is better to keep whole object in dict e.g.

dict(((m.key, m) for m in DictModel.objects.all())

Questions:
Answers:

Perhaps I’m missing something, but Django objects have a __dict__ attribute which seems be what you want.

Questions:
Answers:

To get a map of all of the instances in a queryset into a single dictionary with a specified model field as the key, try doing this

from django.forms.models import model_to_dict
from myApp.models import myModel

allObjs = myModel.objects.all()
f = {}         # initialise the output
key = 'key'    # one of the fields from myModel

[f.update({x[key]: x}) for x in [model_to_dict(y) for y in allObjs]]
return f

Questions:
Answers:

To get values of a models into dictionary, add below code at the place where u need that dictionary

from models import DictModel

activity_map = dict(Plan.objects.values_list('key', 'value'))

activity_map is a dictionary which contains required information .

Questions:
Answers:
user = mymodel.objects.all()
user.values() 

You can also try

user.values_list() # getting as list

Questions:
Answers:

Or were you trying to do something like:

def someview(req):
    models = MyModel.objects.all()
    toTuple = lambda field: (getattr(field, 'someatt'), getattr(field, 'someotheratt'))  
    data = dict(map(toTuple,models))
    return render_to_response(template, data)