Django Queries with many2many & 'through'

I'm quite new to Django and I have some troubles to understand how to fetch data in my database. I think however that my problem is not so complex : I have music works and instruments. To be performed, each work need various instruments in a certain quantity.

Here are my models :

class Instrument(models.Model):      name = models.CharField()      class MusicWork(models.Model):      name = models.CharField()      performers = models.ManyToManyField(Instrument, through='MusicWorkInstrument')      class MusicWorkInstrument(models.Model):      work = models.ForeignKey(MusicWork, on_delete=models.CASCADE)      instrument = models.ForeignKey(Instrument, on_delete=models.CASCADE)      quantity = models.IntegerField()  

Now that I have my database structure, I want to perform some queries. For example, I play the piano and I want to play with my friend who is a violonist.

• How can I ask for all works composed exactly 1 piano and 1 violin?

Let's say we didn't find something interesting, so let's try to find some arrangements:

• How can I get all works with 1 piano and 1 other instrument ?

We changed our mind, and now we would like to find a new fellow musician:

• We need to search for all works with 1 piano, 1 violin, and any other instrument except the bassoon (sorry but it doesn't fit with the violin :( )

I've been trying to figure out how to do these requests for like 3 hours, but as I'm just learning Django, I don't know all the operations on QuerySet and I'm quite confused..

Please, could you help me to find what to play with my friend ? :D

Thank you !

https://stackoverflow.com/questions/67443042/django-queries-with-many2many-through May 08, 2021 at 08:35AM