Django Formset, how to define multiple many to many fields and create a formset

[Sam Hefer]

Hi,

I'm trying to create a formset for a model that has multiple foreign keys and many to many fields.

The goal is the be able to find an item in a pre-populated list of Equipment and Material, select multiple items and add/change the quantity of each item, inside the formset.

I realize that I haven't added the quantity fields in the JobDocket, but I have no idea how to define that kind of relationship.

Models:

class Equipment(models.Model):
    equipment_name = models.CharField(max_length=30)
    supplier = models.CharField(max_length=50, blank=True)
    price = models.DecimalField(max_digits=10, decimal_places=2)
    quantity = models.IntegerField(null=True)
    margin = models.DecimalField(max_digits=3, decimal_places=2, help_text='Input as a decimal e.g: 75% as 0.75')
    photo = models.ImageField()

    def __str__(self):
        return self.equipment_name

class Material(models.Model):
    material_name = models.CharField(max_length=30)
    supplier = models.CharField(max_length=50, blank=True)
    price = models.DecimalField(max_digits=10, decimal_places=2)
    margin = models.DecimalField(max_digits=3, decimal_places=2, help_text='Input as a decimal e.g: 75% as 0.75')
    quantity = models.IntegerField()
    photo = models.ImageField()

    def __str__(self):
        return self.material_name

class JobDocket(models.Model):
    EQUIPMENT_TYPE = (
        ('1', 'Air Conditioning'),
        ('2', 'Heating/Heat-Pump'),
        ('3', 'Refrigeration'),
        ('4', 'Ventilation/Extraction'),
        ('5', 'Electrical/Controls'),
    )

    job = models.ForeignKey(Job, on_delete=models.CASCADE)
    technician = models.ForeignKey(User, on_delete=models.CASCADE)
    site_equipment = models.CharField(choices=EQUIPMENT_TYPE, max_length=50, default='1')
    start_time = models.DateTimeField()
    end_time = models.DateTimeField()
    rate = models.DecimalField(max_digits=20, decimal_places=2, default=80.00)
    mileage = models.IntegerField()
    equipment_used = models.ManyToManyField(Equipment, max_length=500)
    materials_used = models.ManyToManyField(Material, max_length=500)
    description = models.CharField(max_length=1000, help_text='Description of work carried out', blank=False)
    created = models.DateTimeField(default=now, blank=True)

    def __str__(self):
        return str(self.technician)

    def get_absolute_url(self):
        return reverse('jobs:detail', kwargs={'pk': self.pk})

Could someone show me how to define this relationship as well as how to create the formset for it?

Thanks,

Sam