Django admin inline:select_related

Question

在Python 3.4.1上使用带有模型的Django 1.8:

class Product(models.Model):
    name = models.CharField(max_length=255)
    # some more fields here

    def __str__(self):
        return self.name


class PricedProduct(models.Model):
    product = models.ForeignKey(Product, related_name='prices')
    # some more fields here

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

class Coming(models.Model):
    # some unimportant fields here


class ComingProducts(models.Model):
    coming = models.ForeignKey(Coming)
    priced_product = models.ForeignKey(PricedProduct)
    # more unimportant fields

和以下admin.py:

class ComingProductsInline(ForeignKeyCacheMixin, admin.TabularInline):
    model = ComingProducts


class ComingAdmin(admin.ModelAdmin):
    inlines = [ComingProductsInline]

当然,我遇到了对数据库进行多次查询的问题:我对列表中的每个项目进行查询,并对每一行进行查询.所以,有100个项目,我得到100 ^ 2个查询.我已经用Django表单中的ModelChoiceField或ModelMultipleChoiceField的缓存查询集选项解决了每行查询的问题 但是我仍然遇到str方法的问题.我尝试过以下方法:

1)将prefetch_related添加到ComingAdmin:

def get_queryset(self, request):
    return super(ComingAdmin, self).get_queryset(request). \
    prefetch_related('products__product')

2)将select_related添加到ComingProductInline:

def get_queryset(self, request):
    return super(ComingProductsInline, self).get_queryset(request). \
    select_related('priced_product__product')

3)为内联定义自定义表单并将select_related添加到字段查询集:

 class ComingProductsInline(ForeignKeyCacheMixin, admin.TabularInline):
     model = ComingProducts
     form = ComingProductsAdminForm

 class ComingProductsAdminForm(ModelForm):
     def __init__(self, *args, **kwargs):
              super(ComingProductsAdminForm, self).__init__(args, kwargs)
              self.fields['priced_product'].queryset = PricedProduct.objects.all(). \
              select_related('product')

     class Meta:
         model = ComingProducts
         fields = '__all__'

4)定义自定义formset:

 class ComingProductsInline(ForeignKeyCacheMixin, admin.TabularInline):
     model = ComingProducts
     formset = MyInlineFormset

 class MyInlineFormset(BaseInlineFormSet):
     def __init__(self, data=None, files=None, instance=None,
             save_as_new=False, prefix=None, queryset=None, **kwargs):
        super(MyInlineFormset, self).__init__(data, files, instance,
                                          save_as_new, prefix, queryset, **kwargs)
        self.queryset = ComingProducts.objects.all(). \
        prefetch_related('priced_product__product')

5)前4种方法的不同组合

并没有什么帮助:每次调用PricedProduct的str都会让Django对Product表执行查询.所有这些方法都在stackoverflow上提到,但是他们对ModelAdmin进行了处理,并且对Inline没有帮助.我错过了什么？

Answer 1

您会发现这种方法非常有用：

project/admin.py

from django.contrib import admin
from django.contrib.admin.options import BaseModelAdmin
from django.db.models.constants import LOOKUP_SEP


class AdminBaseWithSelectRelated(BaseModelAdmin):
    """
    Admin Base using list_select_related for get_queryset related fields
    """
    list_select_related = []

    def get_queryset(self, request):
        return super(AdminBaseWithSelectRelated, self).get_queryset(request).select_related(*self.list_select_related)

    def form_apply_select_related(self, form):
        for related_field in self.list_select_related:
            splitted = related_field.split(LOOKUP_SEP)

            if len(splitted) > 1:
                field = splitted[0]
                related = LOOKUP_SEP.join(splitted[1:])
                form.base_fields[field].queryset = form.base_fields[field].queryset.select_related(related)


class AdminInlineWithSelectRelated(admin.TabularInline, AdminBaseWithSelectRelated):
    """
    Admin Inline using list_select_related for get_queryset and get_formset related fields
    """

    def get_formset(self, request, obj=None, **kwargs):
        formset = super(AdminInlineWithSelectRelated, self).get_formset(request, obj, **kwargs)

        self.form_apply_select_related(formset.form)

        return formset


class AdminWithSelectRelated(admin.ModelAdmin, AdminBaseWithSelectRelated):
    """
    Admin using list_select_related for get_queryset and get_form related fields
    """

    def get_form(self, request, obj=None, **kwargs):
        form = super(AdminWithSelectRelated, self).get_form(request, obj, **kwargs)

        self.form_apply_select_related(form)

        return form


class FilterWithSelectRelated(admin.RelatedFieldListFilter):
    list_select_related = []

    def field_choices(self, field, request, model_admin):
        return [
            (getattr(x, field.remote_field.get_related_field().attname), str(x))
            for x in self.get_queryset(field)
        ]

    def get_queryset(self, field):
        return field.remote_field.model._default_manager.select_related(*self.list_select_related)

app/admin.py

from django.contrib import admin

from project.admin import AdminWithSelectRelated, AdminInlineWithSelectRelated, FilterWithSelectRelated
from .models import FormaPago, Comprobante, ItemServicio, ItemBazar


class ItemServicioInlineAdmin(AdminInlineWithSelectRelated):
    model = ItemServicio

    list_select_related = (
        'alumno_servicio__alumno__estudiante__profile',
        'alumno_servicio__servicio__grado',
        'comprobante__forma_pago',
    )


class ItemBazarInlineAdmin(AdminInlineWithSelectRelated):
    model = ItemBazar

    list_select_related = (
        'alumno_item__alumno__estudiante__profile',
        'alumno_item__item__anio_lectivo',
        'comprobante__forma_pago',
    )


class ComprobanteAdmin(AdminWithSelectRelated):
    list_display = ('__str__', 'total', 'estado', 'fecha_generado', 'forma_pago', 'tipo', )
    list_filter = ('estado', 'forma_pago', )

    list_select_related = ('forma_pago', )
    inlines = (ItemServicioInlineAdmin, ItemBazarInlineAdmin, )


class AlumnoFilter(FilterWithSelectRelated):
    list_select_related = ('estudiante__profile', )


class ItemServicioAdmin(AdminWithSelectRelated):
    list_display = ('nombre', 'alumno', 'monto_pagado', 'comprobante', )
    list_filter = (
        'alumno_servicio__alumno__seccion__grado',
        ('alumno_servicio__alumno', AlumnoFilter),
    )

    list_select_related = (
        'comprobante__forma_pago',
        'alumno_servicio__alumno__estudiante__profile',
        'alumno_servicio__alumno__seccion__grado',
        'alumno_servicio__servicio__grado',
    )


class ItemBazarAdmin(AdminWithSelectRelated):
    list_display = ('nombre', 'alumno', 'monto_pagado', 'comprobante', )
    list_filter = (
        'alumno_item__alumno__seccion__grado',
        ('alumno_item__alumno', AlumnoFilter),
    )

    list_select_related = (
        'comprobante__forma_pago',
        'alumno_item__alumno__estudiante__profile',
        'alumno_item__alumno__seccion__grado',
        'alumno_item__item__anio_lectivo',
    )


admin.site.register(FormaPago)
admin.site.register(Comprobante, ComprobanteAdmin)
admin.site.register(ItemServicio, ItemServicioAdmin)
admin.site.register(ItemBazar, ItemBazarAdmin)

我所要做的就是定义 select_related 字段和 Custom AdminWithSelectRelated, AdminInlineWithSelectRelated，并将FilterWithSelectRelated它们用于 Changelists、Changeforms 甚至内联 Formsets。

奇迹般有效。

Answer 2

formset解决方案对我有用,但方法略有不同:

class MyInlineFormset(BaseInlineFormSet):
    def __init__(self, *args, **kwargs):
        super(MyInlineFormset, self).__init__(*args, **kwargs)
        self.queryset = self.queryset.prefetch_related('priced_product__product')

BaseInlineFormSet类为您过滤查询集,您需要获取该过滤的查询集并添加预取.使用formset实现(all()查询集),您将获得无关的ComingProduct对象,渲染可能需要很长时间.当它是过滤后的查询集时,它会很快呈现.

Answer 3

受@helpse回答的启发，如果您只想覆盖单个管理内联的查询集，您还可以执行以下操作：

class ComingProductsInline(admin.TabularInline):
    model = ComingProducts

    def get_formset(self, request, obj=None, **kwargs):
        formset = super(ComingProductsInline, self).get_formset(request, obj, **kwargs)
        queryset = formset.form.base_fields["priced_product"].queryset
        queryset = queryset.select_related("product")
        formset.form.base_fields["priced_product"].queryset = queryset
        return formset

对于大多数情况来说这可能就足够了。

Answer 4

我目前正在研究类似的问题。我发现的内容记录在这个线程中：管理中的可翻译多位字段生成许多查询

我所做的一项重要观察是，我的解决方案仅适用于 Django 1.7x，不适用于 1.8。完全相同的代码，对于 d1.7，我有 10^1 个查询的顺序，而在新安装的 d1.8 中，我有 10^4 个查询。