How to get data from Django Many To Many Field?

Question

Can someone explain to me how to get data from a many to many field. My model:

class Subcat(models.Model):
    subcat_name = models.CharField(max_length=128,default='Unknown')
    active1 = models.BooleanField()
    variants = models.ManyToManyField('Variants')
    lang = models.ForeignKey('Lang',default=1)

    def __unicode__(self):
        return self.subcat_name

class Variants(models.Model):
    lang = models.ForeignKey('Lang')
    name  = models.CharField(max_length=256)
    descr = models.CharField(max_length=500,default='Unknown')

    def __unicode__(self):
        return self.name

class Lang(models.Model):
    name  = models.CharField(max_length=25)
    code  = models.CharField(max_length=5)

    def __unicode__(self):
        return self.name

In class Subcat user defines subcategory, default is on English language, for example:

subcat_name = "Museums"
active1 = 1
variants = Muzeji,...
lang = en

So the default language is English, and when I want English subcat it's easy to get

subcategory="Museums"
data= Subcat.objects.get(subcat_name=subcategory)

so my question is: when user uses another language for example

subcategory= "Muzeji"
data=?????

how can I make a query from that information that will return me id where subcat_name is Museums...

Can someone explain me in details How to get data from Many To Many fields or point me to some good tutorial...

Answer 1

subcat= Subcat.objects.get(subcat_name=subcategory)
variant=subcat.variants.filter(name="Muzeji")
lang=variant.lang.name

1. get the subcat object
2. get the appropriate variant with name="Muzeji"
3. now you can access directly to lang:

if you want to return id :

variant=subcat.variants.filter(name="Museums").values('id')