开发一个仅限API的Rails应用程序来使用API中的数据，过滤掉许多字段，然后广播我们想要公开的字段。
我的应用正常返回数据，但我意识到在源API级别上，我们更改了我们要公开的数据字段之一的数据类型。为了适应，我提交了我的工作，检查了一个新分支，运行迁移以更改数据字段的数据类型，我决定对它的工作方式感到满意，回滚迁移，承诺和签出主分支。该应用正常返回数据。但是，现在当我使用.first，.last等查找程序方法在Rails控制台中测试我的模型记录时，我收到以下错误。他们之前工作正常。
我环顾四周，并没有看到任何有关此特定错误的线索（它们似乎都在寻找显示页面的个别记录） - 尽管this和{{3线程（通过扩展名）似乎最接近。并且使用db I m来检查数据库上的用户显示错误中的用户ID（＆＃34; 501＆＃34;）不存在。
我做了什么以及我需要做什么才能再次调用finder方法？我是否需要在我的数据库中的错误中创建引用的用户？ （为什么它不是我一直用来连接到我的数据库的默认用户？错误中的用户ID来自哪里？它甚至重要吗？）
ps - 如果相关，我使用rake db:rollback按照this帖子回滚我的迁移。
提前致谢。
Rails控制台
.2.1 :001 > KoboApi.first
ActiveRecord::NoDatabaseError: local user with ID 501 does not exist
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:661:in `rescue in connect'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `connect'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:242:in `initialize'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-postgis-adapter-3.1.4/lib/active_record/connection_adapters/postgis_adapter.rb:51:in `initialize'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-postgis-adapter-3.1.4/lib/active_record/connection_adapters/postgis/create_connection.rb:37:in `new'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-postgis-adapter-3.1.4/lib/active_record/connection_adapters/postgis/create_connection.rb:37:in `postgis_connection'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:438:in `new_connection'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:448:in `checkout_new_connection'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:422:in `acquire_connection'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:349:in `block in checkout'
from /Users/toby/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:348:in `checkout'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:263:in `block in connection'
from /Users/toby/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:262:in `connection'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:571:in `retrieve_connection'
... 13 levels...
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/railties-4.2.5.1/lib/rails/commands/console.rb:9:in `start'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/railties-4.2.5.1/lib/rails/commands/commands_tasks.rb:68:in `console'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/railties-4.2.5.1/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/railties-4.2.5.1/lib/rails/commands.rb:17:in `<top (required)>'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:274:in `require'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:274:in `block in require'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:240:in `load_dependency'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:274:in `require'
from /Users/toby/code/projects/koboApi-broker/bin/rails:9:in `<top (required)>'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:268:in `load'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:268:in `block in load'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:240:in `load_dependency'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:268:in `load'
from /Users/toby/.rvm/rubies/ruby-2.2.1/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
from /Users/toby/.rvm/rubies/ruby-2.2.1/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
我肯定会收到我的记录 - 他们会进入数据库：
Rails dbconsole
koboApi_development=# select * from kobo_apis limit 1;
id | lemurs_quantity | month_and_year | _geolocation | lemur_category | location_admin1 | location_admin2 | record_id | sighting_month | sighting_year
------+-----------------+----------------+--------------+----------------+-----------------+-----------------+-----------+----------------+---------------
1365 | 1 | | | I_dont_remembe | antsiranana | diana | 1234567 | no_response | 2013
(1 row)
koboApi_development=# \du
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------+-----------
[user] | Superuser, Create role, Create DB, Replication | {}
ActiveRecord::Schema.define(version: 20160705203507) do
# These are extensions that must be enabled in order to support this database
enable_extension "plpgsql"
enable_extension "postgis"
create_table "kobo_apis", force: :cascade do |t|
t.integer "lemurs_quantity"
t.date "month_and_year"
t.text "_geolocation"
t.text "lemur_category"
t.string "location_admin1"
t.string "location_admin2"
t.integer "record_id"
t.string "sighting_month"
t.string "sighting_year"
end
create_table "my_spatial_table", force: :cascade do |t|
t.geography "polygon_data", limit: {:srid=>4326, :type=>"polygon", :geographic=>true}
end
end
我的database.yml
development:
adapter: postgis
encoding: unicode
postgis_extension: postgis # default is postgis
postgis_schema: public # default is public
schema_search_path: public,postgis
database: koboApi_development
pool: 5
test:
adapter: postgresql
encoding: unicode
database: koboApi_test
pool: 5
production:
adapter: postgresql
encoding: unicode
database: koboApi_production
pool: 5
答案 0 :(得分：64)
如果你收到这个错误，那似乎是Spring的问题，而不是数据库：
/Users/yad/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/postgresql_adapter.rb:661:in `rescue in connect': local user with ID 501 does not exist
(ActiveRecord::NoDatabaseError)
在rails根目录下输入：
spring stop
它应该说：
Spring stopped.
之后迁移将会有效！
答案 1 :(得分：6)
我将分享对我有用的东西，这听起来像个笑话，但它不是。
我再打开和关闭。
我的意思是我杀死了需要与我的设置并行运行的Redis实例，隐藏了分支上的本地更改，并再次尝试。它有效！
之后我只杀了Unicorn服务器，弹出存储以恢复我的本地更改并重新启动。是的，它仍然奏效。
这没有任何意义，我知道并且因为没有更好的解释而道歉。
我唯一的猜测是，我可能让Unicorn和Redis服务器运行时间过长（上次我关闭Mac时无法记住），而且可能已经搞砸了。如果是这种情况，那么重新启动整个堆栈可能就是解决方案。
希望这能让你，亲爱的读者，为这个神秘的错误提供思考。
答案 2 :(得分：3)
该错误与您的商家数据无关。查看日志的顶行...
ActiveRecord::NoDatabaseError: local user with ID 501 does not exist
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:661:in `rescue in connect'
from /Users/toby/.rvm/gems/ruby-2.2.1/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `connect'
......很明显Rails无法连接到数据库。
提到的本地用户很可能是一个OS用户，它被配置为访问postgres数据库并且其记录被删除或损坏。
尝试使用控制台中的psql连接到您的数据库，看看是否有任何问题。命令看起来应该是这样的。
psql --host=localhost --port=5432 --username=<your postgres user> --password --dbname=koboApi_development
由于您的数据库配置中未设置username，因此它可能来自环境变量。检查它是否包含正确的值。