Django REST Framework with viewset-router queryset filtering

Question

I am using Django 1.7 and I working with REST Framework, I have implemented a simple API to get all the objects in a Model, but i want to filter the result putting a foreign object value.

For example, actually I can have a list of Objects with this URL

http://localhost:8000/api/ocompradetalle

and if I want only one, i only can put the PK (PrimaryKey) like this

http://localhost:8000/api/ocompradetalle/1/

I want to change the primary key to filter by a Foreign field value, I mean, I have a document (OCompra) with a value on the "folio" field, this document will have many details (OCompraDetalle), so, I want to be able to put something like this:

http://localhost:8000/api/ocompradetalle/F2033

being "F2033" a "folio" value and the response should bring me all the details of the OCompra Object with this value in the "folio" field.

this is what I have at the moment.

urls.py >> I have the router that takes the ViewSets

from rest_framework import routers
from inventario_rfid.views import OCompraViewSet, OCompraDetalleViewSet
from administracion.views import ProductoViewSet

router = routers.DefaultRouter()
router.register(r'ocompra',OCompraViewSet)
router.register(r'ocompradetalle',OCompraDetalleViewSet)
router.register(r'producto',ProductoViewSet)

urlpatterns = patterns('',
...
#APIS
url(r'^api/',include(router.urls)),
)

serializers.py

from rest_framework import serializers
from administracion.serializers import ProductoSerializer
from .models import OCompra, OCompraDetalle

class OCompraSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = OCompra
        fields = ('folio','codigo_proveedor','nombre_proveedor','status','fecha','subtotal','iva','envio',
                  'otro','total',)

class OCompraDetalleSerializer(serializers.HyperlinkedModelSerializer):
    producto = ProductoSerializer(many=False)
    ocompra = OCompraSerializer(many = False) << I WANT TO FILTER BY THIS (ocompra__folio)
    class Meta:
        model = OCompraDetalle
        fields = ('ocompra','producto','cantidad_ordenada','cantidad_recibida','fecha_entrega','precio','epc')

views.py

class OCompraDetalleViewSet(viewsets.ModelViewSet):
    queryset = OCompraDetalle.objects.all()
    serializer_class = OCompraDetalleSerializer


class OCompraViewSet(viewsets.ModelViewSet):
    queryset = OCompra.objects.all()
    serializer_class = OCompraSerializer

models.py

class OCompra(models.Model):
    folio = models.CharField(max_length=15)
    codigo_proveedor = models.CharField(max_length=15)
    nombre_proveedor = models.CharField(max_length=100)
    status = models.IntegerField(default=0)
    fecha = models.DateTimeField(auto_now_add=True)
    usuario = models.ForeignKey(User)
    subtotal = models.DecimalField(default=0,decimal_places=2, max_digits=20)
    iva = models.DecimalField(default=0,decimal_places=2, max_digits=20)
    envio = models.DecimalField(default=0,decimal_places=2, max_digits=20)
    otro = models.DecimalField(default=0,decimal_places=2, max_digits=20)
    total = models.DecimalField(default=0,decimal_places=2, max_digits=20)
    def __unicode__(self):
        return self.folio

class OCompraDetalle(models.Model):
    ocompra = models.ForeignKey(OCompra,related_name='detalles')
    producto = models.ForeignKey(Producto)
    cantidad_ordenada = models.DecimalField(default=0,decimal_places=2, max_digits=10)
    cantidad_recibida = models.DecimalField(default=0,decimal_places=2, max_digits=10)
    fecha_entrega = models.DateField(blank=True,null=True)
    precio = models.DecimalField(default=0,decimal_places=2, max_digits=10)
    epc = models.CharField(max_length=25,null=True,blank=True)

Could you not simply make another route, that is meant to call the API not by primary key, but by filtering on this foreign key? For example: localhost:8000/api/ocompradetalle_filtered_by_folio/F2033 and just write a filter query in the view? — Tadgh
– Tadgh, Commented Oct 27, 2014 at 20:14
How can I put the "folio" value like a parameter in the view? — Alex Lord Mordor
– Alex Lord Mordor, Commented Oct 27, 2014 at 20:23

JoeyP · Accepted Answer · 2014-10-27 21:33:50Z

6

Ok, so if I'm understanding correctly you want to be able to filter on a list of OCompraDetalle objects AND be able to set the lookup field to a value in a joined table (Ocompra). This viewset should do both for you

from rest_framework import filters
OCompraDetalleViewSet(viewsets.ModelViewSet):
    filter_backends = (filters.DjangoFilterBackend,)
    filter_fields = ('precio','ocompra__envio')

    serializer_class = OCompraDetalleSerializer
    queryset = OCompraDetalle.objects.all()
    lookup_field = "ocompra__folio"

So:

http://localhost:8000/api/ocompradetalle/1/

will give you the ocompradetalle object where ocompradetalle.ocompra.folio is equal to 1. This will only work if the mapping is one-to-one or the folio column has a unique index. Detail views cannot return more than one object

If you would like to filter by a column on a joined table you could do:

http://localhost:8000/api/ocompradetalle/?ocompra__envio=blah

And you will get all the ocompradetalles where ocompradetalle.ocompra.envio = blah

answered Oct 27, 2014 at 21:33

JoeyP

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5 Comments

Alex Lord Mordor Over a year ago

This one works perfect if I have one detail for a single purchase order like you said, one-to-one, but I wish to get ALL the details of a purchase order because an order has too many details, actually, every single order has a unique "folio" value. The result of testing your code is this: get() returned more than one OCompraDetalle -- it returned more than 20!

Alex Lord Mordor Over a year ago

I have tested the second option, the filter_field with the question mark, and it returned me all the details successfully. THANK YOU SO MUCH!!

Alex Lord Mordor Over a year ago

do you have an idea why I can't PUT in this api? a get this error when I try to PUT the exactly same JSON: "detail": "Method 'PUT' not allowed."

JoeyP Over a year ago

Are you trying to PUT to the right endpoint? PUT request must use the "detail" view. So, for example "localhost:8000/api/ocompradetalle/1" and not "localhost:8000/api/ocompradetalle"

Alex Lord Mordor Over a year ago

I have resolved it, I was PUTting the whole JSON, like a list, by default, django rest framework can't process that so i have installed django-rest-framework-bulk and then, I can PUT/PATCH now. Thank you!

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