rails 4 activerecord TypeError nil不是符号
看来sql server中的表是在select语句中放置nil 。 我不知道如何解决这个问题，如果我切换到任何其他表，我可以很容易地获得第一个记录。 还有其他人处理过这个bug吗？ 我把桌子分开并构建了一个视图。 它仍然这样做。 猴子修补这个犹豫不决。 想法？ 我是如何连接到SQL Server的：
我的模特：
class Deal < ActiveRecord::Base self.table_name = 'vwStorePromosExtSummaryGlobal' end
我的控制器：
class V1::DealsController 0.6.1' gem 'activerecord-sqlserver-adapter', github: 'arthrex/activerecord-sqlserver-adapter' gem 'active_model_serializers', '~> 0.8.1'
当我打开gem中的确切错误时，我看到：
97: def serializable_hash(options = nil) 98: options ||= {} 99: 100: attribute_names = attributes.keys 101: if only = options[:only] 102: attribute_names &= Array(only).map(&:to_s) 103: elsif except = options[:except] 104: attribute_names -= Array(except).map(&:to_s) 105: end 106: 107: hash = {} 108: => 109: binding.pry 110: 111: attribute_names.each { |n| hash[n] = read_attribute_for_serialization(n) } 112: 113: Array(options[:methods]).each { |m| hash[m.to_s] = send(m) if respond_to?(m) } 114: 115: serializable_add_includes(options) do |association, records, opts| 116: hash[association.to_s] = if records.respond_to?(:to_ary) 117: records.to_ary.map { |a| a.serializable_hash(opts) } 118: else 119: records.serializable_hash(opts) 120: end 121: end 122: 123: hash 124: end [1] pry(#)> p attribute_names.each # => # [2] pry(#)> p attribute_names ["mallid", nil] => ["mallid", nil] [3] pry(#)>
这是我的完整痕迹：
[1m[36mSQL (49.6ms)[0m [1mUSE [pcmenu][0m Processing by V1::DealsController#by_mall_id as JSON Parameters: {"id"=>"1066"} [1m[35mDeal Load (44.5ms)[0m EXEC sp_executesql N'SELECT TOP (1) mallid FROM [StorePromosExtSummaryGlobal] WHERE [StorePromosExtSummaryGlobal].[mallid] = N''1066'' AND (salestypeid = 11 AND calcendDate > ''09-09-2013'' AND displayDate < ''09-09-2013'' AND (promoType is null or promoType = 0)) ORDER BY displayName ASC' Completed 500 Internal Server Error in 546ms TypeError - nil is not a symbol: activemodel (4.0.0) lib/active_model/serialization.rb:108:in `block in serializable_hash' activemodel (4.0.0) lib/active_model/serialization.rb:108:in `serializable_hash' activerecord (4.0.0) lib/active_record/serialization.rb:17:in `serializable_hash' activemodel (4.0.0) lib/active_model/serializers/json.rb:99:in `as_json' activesupport (4.0.0) lib/active_support/json/encoding.rb:50:in `block in encode' activesupport (4.0.0) lib/active_support/json/encoding.rb:81:in `check_for_circular_references' activesupport (4.0.0) lib/active_support/json/encoding.rb:49:in `encode' activesupport (4.0.0) lib/active_support/json/encoding.rb:34:in `encode' activesupport (4.0.0) lib/active_support/core_ext/object/to_json.rb:16:in `to_json' actionpack (4.0.0) lib/action_controller/metal/renderers.rb:90:in `block in ' active_model_serializers (0.8.1) lib/action_controller/serialization.rb:48:in `_render_option_json' actionpack (4.0.0) lib/action_controller/metal/renderers.rb:33:in `block in _handle_render_options' /Users/chrishough/.rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/set.rb:232:in `each' actionpack (4.0.0) lib/action_controller/metal/renderers.rb:30:in `_handle_render_options' actionpack (4.0.0) lib/action_controller/metal/renderers.rb:26:in `render_to_body' actionpack (4.0.0) lib/abstract_controller/rendering.rb:97:in `render' actionpack (4.0.0) lib/action_controller/metal/rendering.rb:16:in `render' actionpack (4.0.0) lib/action_controller/metal/instrumentation.rb:41:in `block (2 levels) in render' activesupport (4.0.0) lib/active_support/core_ext/benchmark.rb:12:in `block in ms' /Users/chrishough/.rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/benchmark.rb:296:in `realtime' activesupport (4.0.0) lib/active_support/core_ext/benchmark.rb:12:in `ms' actionpack (4.0.0) lib/action_controller/metal/instrumentation.rb:41:in `block in render' actionpack (4.0.0) lib/action_controller/metal/instrumentation.rb:84:in `cleanup_view_runtime' activerecord (4.0.0) lib/active_record/railties/controller_runtime.rb:25:in `cleanup_view_runtime' actionpack (4.0.0) lib/action_controller/metal/instrumentation.rb:40:in `render' app/controllers/v1/deals_controller.rb:6:in `by_mall_id' apipie-rails (0.0.22) lib/apipie/dsl_definition.rb:193:in `block in _apipie_define_validators' actionpack (4.0.0) lib/action_controller/metal/implicit_render.rb:4:in `send_action' actionpack (4.0.0) lib/abstract_controller/base.rb:189:in `process_action' actionpack (4.0.0) lib/action_controller/metal/rendering.rb:10:in `process_action' actionpack (4.0.0) lib/abstract_controller/callbacks.rb:18:in `block in process_action' activesupport (4.0.0) lib/active_support/callbacks.rb:383:in `_run__408012802371174283__process_action__callbacks' activesupport (4.0.0) lib/active_support/callbacks.rb:80:in `run_callbacks' actionpack (4.0.0) lib/abstract_controller/callbacks.rb:17:in `process_action' actionpack (4.0.0) lib/action_controller/metal/rescue.rb:29:in `process_action' actionpack (4.0.0) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action' activesupport (4.0.0) lib/active_support/notifications.rb:159:in `block in instrument' activesupport (4.0.0) lib/active_support/notifications/instrumenter.rb:20:in `instrument' activesupport (4.0.0) lib/active_support/notifications.rb:159:in `instrument' actionpack (4.0.0) lib/action_controller/metal/instrumentation.rb:30:in `process_action' actionpack (4.0.0) lib/action_controller/metal/params_wrapper.rb:245:in `process_action' activerecord (4.0.0) lib/active_record/railties/controller_runtime.rb:18:in `process_action' actionpack (4.0.0) lib/abstract_controller/base.rb:136:in `process' actionpack (4.0.0) lib/abstract_controller/rendering.rb:44:in `process' actionpack (4.0.0) lib/action_controller/metal.rb:195:in `dispatch' actionpack (4.0.0) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch' actionpack (4.0.0) lib/action_controller/metal.rb:231:in `block in action' actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:80:in `dispatch' actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:48:in `call' actionpack (4.0.0) lib/action_dispatch/journey/router.rb:71:in `block in call' actionpack (4.0.0) lib/action_dispatch/journey/router.rb:59:in `call' actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:655:in `call' apipie-rails (0.0.22) lib/apipie/static_dispatcher.rb:56:in `call' rack (1.5.2) lib/rack/etag.rb:23:in `call' rack (1.5.2) lib/rack/conditionalget.rb:25:in `call' rack (1.5.2) lib/rack/head.rb:11:in `call' actionpack (4.0.0) lib/action_dispatch/middleware/params_parser.rb:27:in `call' actionpack (4.0.0) lib/action_dispatch/middleware/flash.rb:241:in `call' rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context' rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call' actionpack (4.0.0) lib/action_dispatch/middleware/cookies.rb:486:in `call' activerecord (4.0.0) lib/active_record/query_cache.rb:36:in `call' activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:626:in `call' activerecord (4.0.0) lib/active_record/migration.rb:369:in `call' actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call' activesupport (4.0.0) lib/active_support/callbacks.rb:373:in `_run__980017763409925121__call__callbacks' activesupport (4.0.0) lib/active_support/callbacks.rb:80:in `run_callbacks' actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call' actionpack (4.0.0) lib/action_dispatch/middleware/reloader.rb:64:in `call' actionpack (4.0.0) lib/action_dispatch/middleware/remote_ip.rb:76:in `call' better_errors (0.9.0) lib/better_errors/middleware.rb:84:in `protected_app_call' better_errors (0.9.0) lib/better_errors/middleware.rb:79:in `better_errors_call' better_errors (0.9.0) lib/better_errors/middleware.rb:56:in `call' actionpack (4.0.0) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call' actionpack (4.0.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call' railties (4.0.0) lib/rails/rack/logger.rb:38:in `call_app' railties (4.0.0) lib/rails/rack/logger.rb:21:in `block in call' activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `block in tagged' activesupport (4.0.0) lib/active_support/tagged_logging.rb:25:in `tagged' activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `tagged' railties (4.0.0) lib/rails/rack/logger.rb:21:in `call' actionpack (4.0.0) lib/action_dispatch/middleware/request_id.rb:21:in `call' rack (1.5.2) lib/rack/methodoverride.rb:21:in `call' rack (1.5.2) lib/rack/runtime.rb:17:in `call' activesupport (4.0.0) lib/active_support/cache/strategy/local_cache.rb:83:in `call' rack (1.5.2) lib/rack/lock.rb:17:in `call' actionpack (4.0.0) lib/action_dispatch/middleware/static.rb:64:in `call' railties (4.0.0) lib/rails/engine.rb:511:in `call' railties (4.0.0) lib/rails/application.rb:97:in `call' rack (1.5.2) lib/rack/content_length.rb:14:in `call' puma (2.5.1) lib/puma/server.rb:472:in `handle_request' puma (2.5.1) lib/puma/server.rb:343:in `process_client' puma (2.5.1) lib/puma/server.rb:242:in `block in run' puma (2.5.1) lib/puma/thread_pool.rb:92:in `block in spawn_thread'
虽然我仍然认为这是活动记录中的错误，但我能够通过https://github.com/rails-api/active_model_serializers gem来解决它。 这个gem覆盖了to_json，无需调用活动记录中的bug代码。
还有其他人有更好的答案吗？
更新控制器：
class V1::DealsController < ApplicationController def by_mall_id deals = Deal.where(mallid: params[:id]).first render json: deals, serializer: V1::DealSerializer end end
我的新DealSerializer：
class V1::DealSerializer < ActiveModel::Serializer attributes :MALLID def MALLID object.mallid end end
这是因为您的表没有primary_key 。 您可以像这样运行迁移:(这是rails 5）
class AddFieldToPosaCode < ActiveRecord::Migration[5.0] execute 'ALTER TABLE my_table ADD PRIMARY KEY(my_column)' end