v1.3.1 - FilterFieldError for ParentalManyToManyField

[aliceni81]

Issue summary

I upgrade the wagtail to v7.4.1, using wagtail.search.backends.database as WAGTAILSEARCH_BACKENDS

Steps to reproduce

my code is

from modelcluster.fields import ParentalManyToManyField
class ArticlePage(Page):
research_services = ParentalManyToManyField(ResearchService)
search_fields = Page.search_fields + [
        index.FilterField('researchservice_id'),
    ]

it works well using v1.2.2, but raise FilterFieldError "Cannot filter search results with field "researchservice_id". Please add a suitable index.RelatedFields definition to GKArticlePage.search_fields." using v1.3.1.
I try to change the code to

index.RelatedFields('research_services', [
            index.FilterField('researchservice_id'),
        ]),

but still the same error arise.

Please help!!

Additional information

No response

Can be reproduced

Not confirmed

Technical details

• Python version: Run python --version.
• Django version: Look in your requirements.txt, or run pip show django | grep Version.
• Wagtail version: Look at the bottom of the Settings menu in the Wagtail admin, or run pip show wagtail | grep Version:.
• Browser version: You can use https://www.whatsmybrowser.org/ to find this out.

Working on this

If you would like to contribute to this issue, follow these steps:

• Confirm that the issue is reproducible, either on a fresh Wagtail project or the bakerydemo.
• Once confirmed, view our contributing guidelines, add a comment to the issue once you're ready to start.

[aliceni81]

I found the problem is _get_filter_field_path_for_column in backends/base.py

if (
                        field.many_to_many
                        and field.path_infos[0].join_field == join_field
                    ):
                        # This join matches the first half of the M2M relation referenced by this RelatedFields entry -
                        # if the next join matches the second half, consume them both and descend into this RelatedFields definition.
                        if table_aliases:
                            table2 = self.queryset.query.alias_map[table_aliases[-1]]
                            if table2.join_field == field.path_infos[1].join_field:
                                table_aliases.pop()
                                model = field.related_model
                                search_fields = search_field.fields
                                path.append(search_field)
                                break

I fix it by

if (
                        field.many_to_many
                        and field.path_infos[0].join_field == join_field
                    ):
                        # This join matches the first half of the M2M relation referenced by this RelatedFields entry -
                        # if the next join matches the second half, consume them both and descend into this RelatedFields definition.
                        if table_aliases:
                            table2 = self.queryset.query.alias_map[table_aliases[-1]]
                            if table2.join_field == field.path_infos[1].join_field:
                                table_aliases.pop()
                                model = field.related_model
                                search_fields = search_field.fields
                                path.append(search_field)
                                break
                        else:
                            model = field.related_model
                            search_fields = search_field.fields
                            path.append(search_field)
                            break