ProgrammingError: function lower(bigint) does not exist (Django, AWS RDS, PostgreSQL)

Question

在我的 Django Rest Framework 项目中，我有一个自定义 filter_backends 允许不区分大小写进行过滤：

class CaseInsensitiveOrderingFilter(OrderingFilter):
    
    def filter_queryset(self, request, queryset, view):
        ordering = self.get_ordering(request, queryset, view)
    
        if ordering:
            new_ordering = []
            for field in ordering:
             #   field = str(field)
                print(Lower(field))
                if field.startswith('-'):
                    new_ordering.append(Lower(field[1:]).desc())
                else:
                    new_ordering.append(Lower(field).asc())
            return queryset.order_by(*new_ordering)
    
        return queryset

这在开发中工作正常。

现在我在 elastic beanstalk 上托管了 django 应用程序，并通过亚马逊关系数据库服务 (RDS) 配置了一个 postgresql 数据库。

当我现在尝试调用 API 时，出现此错误：

ProgrammingError at /api/profile_list/ function lower(bigint) does not exist LINE 1: ..."."author_id") GROUP BY "user_user"."id" ORDER BY LOWER(COUN...

HINT: No function matches the given name and argument types. You might need to add explicit type casts.

此错误仅出现在 RDS 部署中。

我尝试在 django 中输入强制转换字段：

field = str(field)

但这不起作用。有什么方法可以在没有 lower 函数的情况下允许不区分大小写的排序，或者我如何有条件地检查它是一个数字（然后转换？）或文本 abd

Answer 1

您收到错误是因为您在可能是 IntegerField 或其他内容的字段上使用了 Lower。您想在实际使用 Lower:

之前检查您的字段是什么

from django.db import models


def get_field_type(field_name, queryset):
    stripped_field_name = field_name.lstrip('-')
    if stripped_field_name in queryset.query.annotations:
        return queryset.query.annotations[stripped_field_name].output_field
    return queryset.model._meta.get_field(stripped_field_name)


class CaseInsensitiveOrderingFilter(OrderingFilter):
    
    def filter_queryset(self, request, queryset, view):
        ordering = self.get_ordering(request, queryset, view)
    
        if ordering:
            new_ordering = []
            for field in ordering:
                if not isinstance(get_field_type(field, queryset), (models.CharField, models.TextField)):
                    # Most of the character type fields inherit from CharField.
                    # I might miss a few fields here so you would need to make sure
                    new_ordering.append(field)
                elif field.startswith('-'):
                    new_ordering.append(Lower(field[1:]).desc())
                else:
                    new_ordering.append(Lower(field).asc())
            return queryset.order_by(*new_ordering)
    
        return queryset

ProgrammingError: function lower(bigint) does not exist (Django, AWS RDS, PostgreSQL)

ProgrammingError: function lower(bigint) does not exist (Django, AWS RDS, PostgreSQL)

django

postgresql

case-insensitive

amazon-web-services

amazon-rds