Django filter query if filter parameter exists

问题

I'm trying to create a django filter with multiple filter parameters (ex. name, age, height). However, I only want to filter by a parameter if it exists...

In my init:

def __init__(self, name=None, age=None, height=None):
    self.name = name
    self.age = age
    self.height = height

in my query:

Person.objects.filter(name=self.name, age=self.age, height=self.height)

However, the problem is since the parameters are optional in the constructor, there is a chance that the filter is looking for None values, which I don't want. If name='mike', age=25, height=None, I only want the filter to use the name and age parameters and exclude the height. Something like:

Person.objects.filter(if self.name: name=self.name, if self.age: age=self.age, if self.height: height=self.height)

Is this possible? Or would I need to first check if every variable exists and have different cases for each possible filter query?

Thanks!

回答1:

from django.db import models as dmodels
filters = dmodels.Q(age=age) & dmodels.Q(name=name)
if height:
    filters &= dmodels.Q(height=height)
Person.objects.filter(filters)

see here

回答2:

If you want to build a generic solution, use a Custom model manager

#manager.py
from django.db.models import Manager


class CustomManager(Manager):
    def custom_filter(self, *args, **kwargs):
        updated_kwargs = {k: v for k, v in kwargs.items() if v is not None}
        return super().filter(*args, **updated_kwargs)

Attach this manager in your model class as,

#models.py
class Person(models.Model):
    objects = CustomManager()
    # other fields

Then, use this custom_filter(...) method to query, similar to the built-in filter()

# example usage
Person.objects.custom_filter(name=self.name, age=self.age, height=self.height)

Note: This custom_filter method will ommit all values that are None

来源：https://stackoverflow.com/questions/59413613/django-filter-query-if-filter-parameter-exists