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在wagtail 2.2.2项目中，我最近在PostgreSQL搜索后端添加了搜索功能。直到我尝试通过给定的标记在经过过滤的PageQuerySet上运行搜索，这都会引发此错误：

FilterFieldError at /blog/tags/tag_slug/

Cannot filter search results with field "tag_id". Please add index.FilterField('tag_id') to BlogPost.search_fields.

Django Version: 2.0.13
Python Version: 3.6.8

...

File "/path/to/env/lib/python3.6/site-packages/wagtail/search/queryset.py" in search
  12.                                      operator=operator,order_by_relevance=order_by_relevance,partial_match=partial_match)

File "/path/to/env/lib/python3.6/site-packages/wagtail/search/backends/base.py" in search
  371.             partial_match=partial_match,File "/path/to/env/lib/python3.6/site-packages/wagtail/search/backends/base.py" in _search
  359.         search_query.check()

File "/path/to/env/lib/python3.6/site-packages/wagtail/search/backends/base.py" in check
  157.         self._get_filters_from_where_node(self.queryset.query.where,check_only=True)

File "/path/to/env/lib/python3.6/site-packages/wagtail/search/backends/base.py" in _get_filters_from_where_node
  108.             child_filters = [self._get_filters_from_where_node(child) for child in where_node.children]

File "/path/to/env/lib/python3.6/site-packages/wagtail/search/backends/base.py" in <listcomp>
  108.             child_filters = [self._get_filters_from_where_node(child) for child in where_node.children]

File "/path/to/env/lib/python3.6/site-packages/wagtail/search/backends/base.py" in _get_filters_from_where_node
  100.             return self._process_filter(field_attname,lookup,value,check_only=check_only)

File "/path/to/env/lib/python3.6/site-packages/wagtail/search/backends/base.py" in _process_filter
  73.                 field_name=field_attname

Exception Type: FilterFieldError at /trust-worthy/tags/presentation/
Exception Value: Cannot filter search results with field "tag_id". Please add index.FilterField('tag_id') to BlogPost.search_fields.

我将FilterField添加到BlogPost模型的search_fields中，就像说的那样，并且在过滤后的集合上返回正确的搜索结果时，它似乎可以很好地工作。现在唯一的问题是，每次Django启动时，它都会显示以下警告：

System check identified some issues:

WARNINGS:
blog.BlogPost: BlogPost.search_fields contains non-existent field 'tag_id'

以下是有关模型设置的基本摘要：

from wagtail.core.models import Page
from wagtail.search import index
from taggit.models import Tag,TaggedItemBase
from modelcluster.contrib.taggit import ClusterTaggableManager
from modelcluster.fields import ParentalKey


class BlogIndex(Page):

    get_context(self,request):
        context = super().get_context(request)

        tag = Tag.objects.get(slug=some_tag_slug)
        pages = BlogPost.objects.descendant_of(self)\
            .live().public().order_by('-date')

        # The above <PageQuerySet> works fine to search
        # until I add this valid working filter:
        pages = pages.filter(tags=tag)

        # ...which causes the original error when searching that is
        # fixed by adding `tag_id` FilterField to BlogPost.search_fields
        pages = pages.search(some_search_query)

        # `pages` is now valid <PostgresSearchResults>
        context['pages'] = pages
        return context


class BlogPostTag(TaggedItemBase):
    content_object = ParentalKey('blog.BlogPost',related_name='tagged_items')


class BlogPost(Page):
    search_fields = Page.search_fields + [
        index.FilterField('tag_id'),# This fixes the error but causes the warning
    ]
    tags = ClusterTaggableManager(through=BlogPostTag,blank=True)

我的问题是-我在做错什么导致引起关于不存在字段的警告？现在，在筛选后的列表上搜索可以正常工作，但是tag_id不在BlogPost模型上的字段上也确实如此。是否有另一种正确的方法可以解决Cannot filter search results错误并获得相同的结果？