因此，当您在 Rails 中使用wash_out gem，并且客户端发送错误的 XML 时，响应如下：
<html>…
<body>
<h1>REXML::ParseException</h1>
…
而不是正确的 SOAP 响应，如下所示：
<soap:Body>
<soap:Fault>
<faultcode>soap:Client</faultcode>
…
我首先尝试修补wash_out 本身。我设法在其测试中重现了 REXML::ParseException，但随后令我沮丧的是，Rails 在wash_out 触及参数之前实际上解析（并爆炸）错误的 XML。
那么，wash_out gem 应该如何挂钩到 Rails 中，以便它可以挽救那些异常，只针对它拥有的路由？
这是我们必须使用的回溯。我很确定其中有些地方非常适合挂钩，但我还不知道是哪一个：
malformed XML: missing tag start
Line: 13
Position: 558
Last 80 unconsumed characters:
<urn: <Width xsi:type="xsd:int">1</Width> <Height x
Line: 13
Position: 558
Last 80 unconsumed characters:
<urn: <Width xsi:type="xsd:int">1</Width> <Height x):
/home/rking/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/rexml/parsers/treeparser.rb:95:in `rescue in parse'
/home/rking/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/rexml/parsers/treeparser.rb:20:in `parse'
/home/rking/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/rexml/document.rb:231:in `build'
/home/rking/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/rexml/document.rb:43:in `initialize'
activesupport (3.2.8) lib/active_support/xml_mini/rexml.rb:30:in `new'
activesupport (3.2.8) lib/active_support/xml_mini/rexml.rb:30:in `parse'
activesupport (3.2.8) lib/active_support/xml_mini.rb:80:in `parse'
activesupport (3.2.8) lib/active_support/core_ext/hash/conversions.rb:90:in `from_xml'
actionpack (3.2.8) lib/action_dispatch/middleware/params_parser.rb:41:in `parse_formatted_parameters'
actionpack (3.2.8) lib/action_dispatch/middleware/params_parser.rb:17:in `call'
actionpack (3.2.8) lib/action_dispatch/middleware/flash.rb:242:in `call'
rack (1.4.1) lib/rack/session/abstract/id.rb:205:in `context'
rack (1.4.1) lib/rack/session/abstract/id.rb:200:in `call'
actionpack (3.2.8) lib/action_dispatch/middleware/cookies.rb:339:in `call'
activerecord (3.2.8) lib/active_record/query_cache.rb:64:in `call'
activerecord (3.2.8) lib/active_record/connection_adapters/abstract/connection_pool.rb:473:in `call'
actionpack (3.2.8) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (3.2.8) lib/active_support/callbacks.rb:405:in `_run__937528092__call__217727214__callbacks'
activesupport (3.2.8) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.8) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
activesupport (3.2.8) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.8) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (3.2.8) lib/action_dispatch/middleware/reloader.rb:65:in `call'
actionpack (3.2.8) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
actionpack (3.2.8) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
actionpack (3.2.8) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
railties (3.2.8) lib/rails/rack/logger.rb:26:in `call_app'
railties (3.2.8) lib/rails/rack/logger.rb:16:in `call'
actionpack (3.2.8) lib/action_dispatch/middleware/request_id.rb:22:in `call'
rack (1.4.1) lib/rack/methodoverride.rb:21:in `call'
rack (1.4.1) lib/rack/runtime.rb:17:in `call'
activesupport (3.2.8) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.4.1) lib/rack/lock.rb:15:in `call'
actionpack (3.2.8) lib/action_dispatch/middleware/static.rb:62:in `call'
railties (3.2.8) lib/rails/engine.rb:479:in `call'
railties (3.2.8) lib/rails/application.rb:223:in `call'
rack (1.4.1) lib/rack/content_length.rb:14:in `call'
railties (3.2.8) lib/rails/rack/log_tailer.rb:17:in `call'
rack (1.4.1) lib/rack/handler/webrick.rb:59:in `service'
/home/rking/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
/home/rking/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
/home/rking/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'
谢谢！—☈