Connecting Django Models with outer applications

Published at Jan. 23, 2012 | Tagged with: , , , ,

Preface: Sometimes, parts of the data that you have to display in your application reside out of the Django models. Simple example for this is the following case - the client requires that you build them a webshop but they already have CRM solution that holds their products info. Of course they provide you with a mechanism to read this data from their CRM.

Specialty: The problem is that the data in their CRM does not hold some of the product information that you need. For instance it misses SEO-friendly description and product image. So you will have to set up a model at your side and store these images there. It is easy to join them, the only thing that you will need is a simple unique key for every product.

Solution: Here we use the product_id field to make the connection between the CRM data and the Django model.

# in models.py
class Product(models.Model):
    product_id = models.IntegerField(_('Original Product'),
                                     unique=True)
    description = models.TextField(_('SEO-friendly Description'),
                                   blank=True)
    pod_image = FilerImageField(verbose_name=_('Product Image'),
                                blank=True, null=True)

   @property
   def name(self):
       return crm_api.get_product_name(self.product_id)

# in forms.py
class ProductForm(forms.ModelForm):
    name = forms.CharField(required=False,
                           widget=forms.TextInput(attrs={
                               'readonly': True,
                               'style': 'border: none'}))

    class Meta:
        model = Product
        widgets = {
            'product_id': forms.Select(),
        }
    def __init__(self, *args, **kwargs):
        super(ProductForm, self).__init__(*args, **kwargs)
        self.fields['product_id'].widget.choices = crm_api.get_product_choices()
        if self.instance.id:
            self.fields['name'].initial = self.instance.name

The form here should be used in the admin(add/edit) page of the model. We define that the product_id field will use the select widget and we use a method that connect to the CRM and returns the product choices list.
The "self.instance.id" check is used to fill the name field for product that are already saved.

Final words: This is a very simple example but its idea is to show the basic way to connect your models with another app. I strongly recommend you to use caching if your CRM data is not modified very often in order to save some bandwidth and to speed up your application.
Also if you have multiple field it may be better to overwrite the __getattr__ method instead of defining separate one for each property that you need to pull from the outer application.

P.S. Thanks to Miga for the code error report.

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