如何在django管理界面中使用外键字段数据创建圆环图？

from django.db import models

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

    def __str__(self):
        return self.name

class Product(models.Model):
    name = models.CharField(max_length=100)
    category = models.ForeignKey(Category, on_delete=models.CASCADE)

    def __str__(self):
        return self.name

from django.contrib import admin
from .models import Category, Product
import matplotlib.pyplot as plt

class ProductAdmin(admin.ModelAdmin):
    def get_charts(self, obj):
        # 根据外键字段获取关联的Category对象
        category = obj.category

        # 统计该Category下的产品数量
        product_count = Product.objects.filter(category=category).count()

        # 绘制圆环图
        labels = ['Category', 'Other']
        sizes = [product_count, 100 - product_count]
        colors = ['#ff9999', '#66b3ff']
        explode = (0.1, 0)
        plt.pie(sizes, explode=explode, labels=labels, colors=colors, autopct='%1.1f%%', startangle=90)
        plt.axis('equal')
        plt.title('Product Distribution')
        plt.show()

    get_charts.short_description = 'Product Distribution'

    list_display = ('name', 'category', 'get_charts')

admin.site.register(Category)
admin.site.register(Product, ProductAdmin)