使用 external_id 属性设置为现有主题的 external_id 的 /posts.json 路由发出 API 请求时，会触发类似以下的错误：
ActiveRecord::RecordNotUnique (PG::UniqueViolation: ERROR: duplicate key value violates unique constraint \"index_topics_on_external_id\" DETAIL: Key (external_id)=(obCopying text to the system clipboard) already exists.)
当使用 Discourse API gem 发出请求时，响应只是一个 HTML 字符串：
`#<DiscourseApi::Error:"
...`如果以其他方式发出请求，例如使用 HTTParty，响应对象看起来像这样：
response = HTTParty.post(url, body:, headers:)
add_note_to_db(title, response)
# Try getting the `response` object from the response
p response.response
# outputs:
#<Net::HTTPInternalServerError 500 Internal Server Error readbody=true>
这没什么用。
以下是触发问题的调用：
lib/topic_creator.rb:237:in `save_topic'
lib/topic_creator.rb:58:in `create'
lib/post_creator.rb:490:in `create_topic'
lib/post_creator.rb:190:in `block in create'
lib/post_creator.rb:390:in `block in transaction'
lib/post_creator.rb:390:in `transaction'
lib/post_creator.rb:188:in `create'
lib/new_post_manager.rb:318:in `perform_create_post'
lib/new_post_manager.rb:252:in `perform'
app/controllers/posts_controller.rb:210:in `block in create'
lib/distributed_memoizer.rb:16:in `block in memoize'
lib/distributed_mutex.rb:53:in `block in synchronize'
lib/distributed_mutex.rb:49:in `synchronize'
lib/distributed_mutex.rb:49:in `synchronize'
lib/distributed_mutex.rb:34:in `synchronize'
lib/distributed_memoizer.rb:12:in `memoize'
app/controllers/posts_controller.rb:209:in `create'
我认为需要在 TopicCreator#create 中引发一个错误，在 PostCreator#create 的事务块中捕获它，然后在 posts 控制器中处理它。
从我的角度来看，理想的解决方案是返回一个指示哪个主题正在使用外部 ID 的错误。
在 TopicCreator#create 中引发错误：
def create
topic = Topic.new(setup_topic_params)
if topic.external_id.present? && Topic.with_deleted.exists?(external_id: topic.external_id)
existing_topic = Topic.with_deleted.find_by(external_id: topic.external_id)
raise DuplicateExternalIdError.new(existing_topic), "External ID must be unique. Existing topic ID: #{existing_topic.id}"
end
#...
# There's probably an existing error class that could handle this, but sticking this at the bottom of the topic_creator class works for me:
class DuplicateExternalIdError < StandardError
attr_reader :topic
def initialize(topic)
@topic = topic
end
end
在 PostCreator#create 中捕获它：
def create
if valid?
begin
transaction do
build_post_stats
create_topic # this is where the error is happening
# ...
end
rescue TopicCreator::DuplicateExternalIdError => e
@errors.add(:base, "External ID must be unique. Existing topic ID: #{e.topic.id}")
end
end
在 posts 控制器中处理它：
# posts_controller.rb
def handle_duplicate_external_id_error(exception)
render json: { error: "External ID must be unique. Existing topic ID: #{exception.topic.id}" }, status: :unprocessable_entity
end
这可能过于针对我的用例，不适合作为正确的解决方案。它与此处提到的关于外部 ID 和重复主题的问题有关：API topic's external_ID can't be reused after deleting a topic and creating a new one - #2 by simon Discourse API 的应用程序可以使用响应消息来取消删除并更新已在使用外部 ID 的主题。