Django Tastypie Advanced Filtering: How to do complex lookups with Q objects

django, django-q, python, tastypie

Solution

You are on the right track. However, `build_filters` is supposed to transition resource lookup to an ORM lookup.

The default implementation splits the query keyword based on `__` into key_bits, value pairs and then tries to find a mapping between the resource looked up and its ORM equivalent.

Your code is not supposed to apply the filter there only build it. Here is an improved and fixed version:

def build_filters(self, filters=None):
    if filters is None:
        filters = {}
    orm_filters = super(BusinessResource, self).build_filters(filters)

    if('query' in filters):
        query = filters['query']
        qset = (
                Q(name__icontains=query) |
                Q(description__icontains=query) |
                Q(email__icontains=query)
                )
        orm_filters.update({'custom': qset})

    return orm_filters

def apply_filters(self, request, applicable_filters):
    if 'custom' in applicable_filters:
        custom = applicable_filters.pop('custom')
    else:
        custom = None

    semi_filtered = super(BusinessResource, self).apply_filters(request, applicable_filters)

    return semi_filtered.filter(custom) if custom else semi_filtered

Because you are using Q objects, the standard `apply_filters` method is not smart enough to apply your custom filter key (since there is none), however you can quickly override it and add a special filter called "custom". In doing so your `build_filters` can find an appropriate filter, construct what it means and pass it as custom to apply_filters which will simply apply it directly rather than trying to unpack its value from a dictionary as an item.

Problem

I have a basic Django model like: ``` class Business(models.Model): name = models.CharField(max_length=200, unique=True) email = models.EmailField() phone = models.CharField(max_length=40, blank=True, null=True) description = models.TextField(max_length=500) ``` I need to execute a complex query on the above model like: ``` qset = ( Q(name__icontains=query) | Q(description__icontains=query) | Q(email__icontains=query) ) results = Business.objects.filter(qset).distinct() ``` I have tried the following using tastypie with no luck: ``` def build_filters(self, filters=None): if filters is None: filters = {} orm_filters = super(BusinessResource, self).build_filters(filters) if('query' in filters): query = filters['query'] print query qset = ( Q(name__icontains=query) | Q(description__icontains=query) | Q(email__icontains=query) ) results = Business.objects.filter(qset).distinct() orm_filters = {'query__icontains': results} return orm_filters ``` and in class Meta for tastypie I have filtering set as: ``` filtering = { 'name: ALL, 'description': ALL, 'email': ALL, 'query': ['icontains',], } ``` Any ideas to how I can tackle this? Thanks - Newton

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