Using voting-enabled models

Once a model is voting-enabled a number of special fields are available on all instances:

Fields

Votable objects have the following fields:

votes

Manager to of all Vote objects related to the current model (typically doesn’t need to be accessed directly). Can be renamed by passing votes_name parameter to SECRETBALLOT_FOR_MODELS, for example:

SECRETBALLOT_FOR_MODELS = {
    "<app_label.model_name>": {
        "votes_name": "vs",
    },
}

total_upvotes

Total number of +1 votes. Can be renamed by passing upvotes_name parameter to SECRETBALLOT_FOR_MODELS, for example:

SECRETBALLOT_FOR_MODELS = {
    "<app_label.model_name>": {
        "upvotes_name": "total_upvs",
    },
}

total_downvotes

Total number of -1 votes. Can be renamed by passing downvotes_name parameter to SECRETBALLOT_FOR_MODELS, for example:

SECRETBALLOT_FOR_MODELS = {
    "<app_label.model_name>": {
        "downvotes_name": "total_downvs",
    },
}

vote_total

Shortcut accessor for (total_upvotes minus total_downvotes). Can be renamed by passing total_name parameter to SECRETBALLOT_FOR_MODELS, for example:

SECRETBALLOT_FOR_MODELS = {
    "<app_label.model_name>": {
        "total_name": "v_total",
    },
}

_secretballot_enabled

Boolean indicating that secretballot is enabled (can be tested for with hasattr). Cannot be renamed, exists for a reliable check that secretballot is available even if all other fields were renamed.

Methods

Votable objects have the following custom methods:

add_vote(token, vote):

Adds or updates the vote for said token. Can be renamed by passing add_vote_name parameter to SECRETBALLOT_FOR_MODELS, for example:

SECRETBALLOT_FOR_MODELS = {
    "<app_label.model_name>": {
        "add_vote_name": "add_v",
    },
}

Parameters

token (str) – mandatory token
vote (int) – value of this vote (+1, 0, or -1) (0 deletes the vote)

remove_vote(token):

Removes the vote (if present) for said token. Can be renamed by passing remove_vote_name parameter to SECRETBALLOT_FOR_MODELS, for example:

SECRETBALLOT_FOR_MODELS = {
    "<app_label.model_name>": {
        "remove_vote_name": "remove_v",
    },
}

Parameters: token (str) – mandatory token

Manager functions

A special manager is added that enables the inclusion of total_upvotes and total_downvotes as well as some extra functionality.

This manager by default replaces the objects manager, but this can be altered by passing the manager_name parameter to SECRETBALLOT_FOR_MODELS, for example:

SECRETBALLOT_FOR_MODELS = {
    "<app_label.model_name>": {
        "manager_name": "ballot_custom_manager",
    },
}

There is also an additional method on the Votable manager:

from_request(request):

When called on a votable object’s queryset will add a user_vote attribute that is the vote cast by the current ‘user’ (actually the token assigned to the request), for example:

def story_view(request, slug):
    story = Story.objects.from_request(request).get(pk=slug)
    # story has the following extra attributes
    # user_vote: -1, 0, or +1
    # total_upvotes: total number of +1 votes
    # total_downvotes: total number of -1 votes
    # vote_total: total_upvotes-total_downvotes
    # votes: related object manager to get specific votes (rarely needed)

Parameters: request (django.http.HttpRequest) – the request object.
Return type: instance of django.db.models.query.QuerySet.

Tokens and SecretBallotMiddleware

Without user logins it is impossible to be certain that a user does not vote more than once, but there are several methods to limit abuses. secretballot takes a fairly hands-off approach to this problem, the Vote object has a token field that is used to store a uniquely identifying token generated from a request. To limit how many votes come from a particular ip address it is sufficient to set the token to the IP address, but it is also possible to develop more sophisticated heuristics to limit voters.

secretballot uses a simple piece of middleware to do this task, and makes it trival for users to define their own middleware that will use whatever heuristic they desire.

secretballot.middleware.SecretBallotMiddleware is an abstract class that defines a generate_token(request) method that should return a string to be used for the token.

For convenience several middleware have already been defined:

secretballot.middleware.SecretBallotIpMiddleware

Simply sets the token to request.META['REMOTE_ADDR'] – the user’s IP address

secretballot.middleware.SecretBallotIpUseragentMiddleware

Sets the token to a hash of the user’s ip address and user agent – hopefully slightly more unique than IP alone.

If you wish to define your own middleware simply derive a class from secretballot.middleware.SecretBallotMiddleware and implement the generate_token method. If you come up with something that may be useful for others contributions are always welcome.

Generic views

secretballot.views includes the following generic views:

vote(request, content_type, object_id, vote, can_vote_test=None, redirect_url=None, template_name=None, template_loader=loader, extra_context=None, context_processors=None, mimetype=None):

This view creates or alters a vote on the object of content_type with a primary key of object_id. If a vote already exists it will be replaced (unless vote is 0 in which case it will be deleted).

The token attribute of the vote that is used to prevent unlimited voting is set within this view based on the active SecretBallotMiddleware class.

Depending on the parameters given the return value of this view varies:

if redirect_url is specified it will be used no matter what
if template_name is specified it will be used (along with template_loader, context_processors and etc.)
without redirect_url or template_name a text/json response will be returned

Parameters

request (django.http.HttpRequest) – the request object.
content_type – class that voting is taking place on (a VotableModel-derived model). May be an instance of django.contrib.contenttypes.models.ContentType, the model class itself, or an app_label.model_name string.
object_id (str) – primary key of object to vote on
vote (int) – value of this vote (+1, 0, or -1) (0 deletes the vote)
can_vote_test –
(Optional) function that allows limiting if user can vote or not. It’s an optional argument to the view that can be specified in the urlconf that is called before a vote is recorded for a user

Example implementation of can_vote_test:
```
from secretballot.utils import get_vote_model

def only_three_votes(request, content_type, object_id, vote):
    return get_vote_model().objects.filter(
            content_type=content_type,
            token=request.secretballot_token,
    ).count() < 3
```
All can_vote_test methods must take the non-optional parameters to secretballot.views.vote and should return True if the vote should be allowed. If the vote is not allowed by default the view will return a 403, but it is also acceptable to raise a different exception.
redirect_ur (str) – (Optional) url to redirect to, if present will redirect instead of returning a normal HttpResponse
template_name (str) – (Optional) template to render to, recieves a context containing content_obj which is the object voted upon
template_loader – (Optional) template loader to use, defaults to django.template.loader
extra_context (dict) – (Optional) dictionary containing any extra context, callables will be called at render time
context_processors – (Optional) list of context processors for this view
mimetype (str) – (Optinal) mimetype override

Return type

django.http.HttpResponse