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我一直在尝试在我的 Django 后端代码中实现 trigram_similar 功能。我收到一个错误：

在此处输入图像描述

web_1         | Traceback (most recent call last):

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/exception.py", line 41, in inner

web_1         |     response = get_response(request)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 187, in _get_response

web_1         |     response = self.process_exception_by_middleware(e, request)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 185, in _get_response

web_1         |     response = wrapped_callback(request, *callback_args, **callback_kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view

web_1         |     return view_func(*args, **kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/views/generic/base.py", line 68, in view

web_1         |     return self.dispatch(request, *args, **kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-packages/rest_framework/views.py", line 489, in dispatch

web_1         |     response = self.handle_exception(exc)

web_1         |   File "/usr/local/lib/python3.6/site-packages/rest_framework/views.py", line 449, in handle_exception

web_1         |     self.raise_uncaught_exception(exc)

web_1         |   File "/usr/local/lib/python3.6/site-packages/rest_framework/views.py", line 486, in dispatch

web_1         |     response = handler(request, *args, **kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-packages/rest_framework/generics.py", line 201, in get

web_1         |     return self.list(request, *args, **kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-packages/rest_framework/mixins.py", line 40, in list

web_1         |     queryset = self.filter_queryset(self.get_queryset())

web_1         |   File "/usr/local/lib/python3.6/site-packages/profilehooks.py", line 239, in new_fn

web_1         |     return fp(*args, **kw)

web_1         |   File "/usr/local/lib/python3.6/site-packages/profilehooks.py", line 347, in __call__

web_1         |     return profiler.runcall(self.fn, *args, **kw)

web_1         |   File "/usr/local/lib/python3.6/cProfile.py", line 109, in runcall

web_1         |     return func(*args, **kw)

web_1         |   File "/code/src/users/views.py", line 266, in filter_queryset

web_1         |     major__name__trigram_similar = "CS"

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 784, in filter

web_1         |     return self._filter_or_exclude(False, *args, **kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/db/models/query.py", line 802, in _filter_or_exclude

web_1         |     clone.query.add_q(Q(*args, **kwargs))

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/db/models/sql/query.py", line 1250, in add_q

web_1         |     clause, _ = self._add_q(q_object, self.used_aliases)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/db/models/sql/query.py", line 1276, in _add_q

web_1         |     allow_joins=allow_joins, split_subq=split_subq,

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/db/models/sql/query.py", line 1210, in build_filter

web_1         |     condition = self.build_lookup(lookups, col, value)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/db/models/sql/query.py", line 1102, in build_lookup

web_1         |     lhs = self.try_transform(lhs, name, lookups)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/db/models/sql/query.py", line 1120, in try_transform

web_1         |     (name, lhs.output_field.__class__.__name__))

web_1         | django.core.exceptions.FieldError: Unsupported lookup 'trigram_similar' for CharField or join on the field not permitted.

web_1         | 2018-11-11 19:03:58,144 ERROR Internal Server Error: /mentors/

web_1         | Traceback (most recent call last):

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/exception.py", line 41, in inner

web_1         |     response = get_response(request)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 187, in _get_response

web_1         |     response = self.process_exception_by_middleware(e, request)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 185, in _get_response

web_1         |     response = wrapped_callback(request, *callback_args, **callback_kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view

web_1         |     return view_func(*args, **kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-packages/django/views/generic/base.py", line 68, in view

web_1         |     return self.dispatch(request, *args, **kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-packages/rest_framework/views.py", line 489, in dispatch

web_1         |     response = self.handle_exception(exc)

web_1         |   File "/usr/local/lib/python3.6/site-
packages/rest_framework/views.py", line 449, in handle_exception

web_1         |     self.raise_uncaught_exception(exc)

web_1         |   File "/usr/local/lib/python3.6/site-
packages/rest_framework/views.py", line 486, in dispatch

web_1         |     response = handler(request, *args, **kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-
packages/rest_framework/generics.py", line 201, in get

web_1         |     return self.list(request, *args, **kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-
packages/rest_framework/mixins.py", line 40, in list

web_1         |     queryset = self.filter_queryset(self.get_queryset())

web_1         |   File "/usr/local/lib/python3.6/site-
packages/profilehooks.py", line 239, in new_fn

web_1         |     return fp(*args, **kw)

web_1         |   File "/usr/local/lib/python3.6/site-
packages/profilehooks.py", line 347, in __call__

web_1         |     return profiler.runcall(self.fn, *args, **kw)

web_1         |   File "/usr/local/lib/python3.6/cProfile.py", line 109, 
in runcall

web_1         |     return func(*args, **kw)

web_1         |   File "/code/src/users/views.py", line 266, in 
filter_queryset

web_1         |     major__name__trigram_similar = "CS"

web_1         |   File "/usr/local/lib/python3.6/site-
packages/django/db/models/query.py", line 784, in filter

web_1         |     return self._filter_or_exclude(False, *args, **kwargs)

web_1         |   File "/usr/local/lib/python3.6/site-
packages/django/db/models/query.py", line 802, in _filter_or_exclude

web_1         |     clone.query.add_q(Q(*args, **kwargs))

web_1         |   File "/usr/local/lib/python3.6/site-
packages/django/db/models/sql/query.py", line 1250, in add_q

web_1         |     clause, _ = self._add_q(q_object, self.used_aliases)

web_1         |   File "/usr/local/lib/python3.6/site-
packages/django/db/models/sql/query.py", line 1276, in _add_q

web_1         |     allow_joins=allow_joins, split_subq=split_subq,

web_1         |   File "/usr/local/lib/python3.6/site-
packages/django/db/models/sql/query.py", line 1210, in build_filter

web_1         |     condition = self.build_lookup(lookups, col, value)

web_1         |   File "/usr/local/lib/python3.6/site-
packages/django/db/models/sql/query.py", line 1102, in build_lookup

web_1         |     lhs = self.try_transform(lhs, name, lookups)

web_1         |   File "/usr/local/lib/python3.6/site-
packages/django/db/models/sql/query.py", line 1120, in try_transform

web_1         |     (name, lhs.output_field.__class__.__name__))

web_1         | django.core.exceptions.FieldError: Unsupported lookup 'trigram_similar' for CharField or join on the field not permitted.

I've followed the instructions on this page https://docs.djangoproject.com/en/2.0/ref/contrib/postgres/lookups/ but to no avail. I have properly installed the dependencies and added the extra files.

     for item in query:
                     item_alias = trans_dict.get(item.lower(),item)
                     major_alias = major_dict.get(item.lower(),item)
                     queryset = queryset.filter(
                         major__name__trigram_similar = major_alias
                     )
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1 回答 1

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查找允许您使用专用的trigram_similarPostgreSQL 扩展执行三元组查找，测量共享的三元组（三个连续字符）的数量。给三元组查找一个表达式并返回相似度测量值大于当前相似度阈值的结果。

要使用它，django.contrib.postgres请在您的中添加“”INSTALLED_APPS并激活pg_trgmPostgreSQL 上的扩展。TrigramExtension您可以使用迁移操作安装扩展。

您需要为有app.model问题的以下内容创建一个新的空白迁移：

from django.contrib.postgres.operations import TrigramExtension

class Migration(migrations.Migration):
    operations = [
        TrigramExtension(),
    ]

这一切都必须手动完成（确保在其中保留依赖项）。

python manage.py makemigrations <insert_app_name_here> --empty

**NB 值得注意的是，您的数据库后端需要 PostgreSQL...

于 2021-02-26T15:16:37.953 回答