当请求数据库连接池但未定义时引发此错误。
源代码: 显示 | 在GitHub上
# File activerecord/lib/active_record/errors.rb, line 90 def initialize(message = nil, connection_name: nil, role: nil, shard: nil) super(message) @connection_name = connection_name @role = role @shard = shard end