How to import related objects and their relationships.

When I import models like following:

class Category(models.Model):
   name = models.CharField(max_length=100, db_index=True)

class Subcategory(models.Model):
   name = models.CharField(max_length=100, db_index=True)
   slug = models.SlugField(max_length=200, db_index=True)
   category = models.ForeignKey(Category, blank=True)

class Product(models.Model):
   name = models.CharField(max_length=100) 
   category = models.ForeignKey(Category, blank=True, null=True)
   subcategory = models.ForeignKey(Subcategory, blank=True, null=True)

Everything is imported thanks to ForeignKeyWidget, but how can I import relations when my csv file looks something like that:

id | product_name | category | subcategory – | T-Shirt A | His | summer – | T-Shirt B | Her | summer

?

As you see ‘summer’ subcategory name isn’t unique and I need to set the proper relationship like:

‘His’ < ‘summer’ < ‘T-Shirt A’ ‘Her’ < ‘summer’ < ‘T-Shirt A’

during import.

How can I achieve it?

I will be grateful for your help.

[gthieleb]

I have solved this in my current project (for importing ManyToMany Values) with subclassing import_field and calling a clean_FOO method (adapted the code from dehydrate_FOO). Within the clean method (example here are ManyToMany fields disks and filesystems) you can get the correct subcategory or create the instance with Django’s get_or_create method (Careful about the return values here).

class SpecResource(resources.ModelResource):

    disks = fields.Field(column_name='Disks')
    filesystems = fields.Field(column_name='Filesystems')

    class Meta:
	model = Spec
	exclude = []

    def import_field(self, field, obj, data):

	field_name = self.get_field_name(field)
	method = getattr(self, 'clean_%s' % field_name, None)
	if method is not None:
	    obj = method(field, obj, data)

        super(SpecResource, self).import_field(field, obj, data)


    def clean_disks(self, field, obj, data):

	disks = []
	cell = data[field.column_name]
	for e in cell.split(','):
	    e = e.strip().split('-')
	    if len(e) < 3:
	        continue
	    size, disk_type, quality = e
	    qualityi, created = StorageQuality.objects.get_or_create(quality=quality)
	    diski, created = Disk.objects.get_or_create(size=size, disk_type=disk_type, quality=qualityi)
	    disks.append(diski)
	obj.disks = disks
	return obj

    def clean_filesystems(self, field, obj, data):

	filesystems = []
	cell = data[field.column_name]
	for e in cell.split(','):
	    e = e.strip().split('-')
	    if len(e) < 3:
	        continue
	    mount, size, quality = e
	    qualityi, created = StorageQuality.objects.get_or_create(quality=quality)
	    filesystemi, created = Filesystem.objects.get_or_create(mount=mount, size=size, quality=qualityi)
	    filesystems.append(filesystemi)
	obj.filesystems = filesystems
	return obj

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