使用机架中间件捕获无效的JSON解析错误 [英] Catching Invalid JSON Parse Errors with Rack Middleware

问题描述

我正在使用Rails 5，并且试图改善对我的API的无效JSON请求的错误处理.

I am using Rails 5 and I am trying to improve error handling for invalid JSON requests to my API.

我尝试通过抢救在控制器中进行解析来处理无效格式的JSON，但意识到Rails中间件在用户向其请求标头添加Content Type时会在我的JSON请求到达控制器之前对其进行解析.

I tried handling invalid format JSON by parsing in the controller with a rescue but realised that Rails middleware is parsing my JSON request before it hits the controller if a user adds Content Type to their request header.

我遵循以下指南: https://robots.thoughtbot.com/catching-json-parse -errors-with-custom-middleware

但是，启动服务器时出现以下错误:

However, I get the following error when starting the server:

.rbenv/versions/2.3.1/lib/ruby​​/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/stack.rb:108:在'assert_index'中:没有这样的中间件插入之前:ActionDispatch :: ParamsParser(RuntimeError)

.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/stack.rb:108:in `assert_index': No such middleware to insert before: ActionDispatch::ParamsParser (RuntimeError)

现在，这意味着ActionDispatch :: ParamsParser没有运行.我认为它在Rails 5中已弃用，因此排除了该选项.

Now, what this means is that ActionDispatch::ParamsParser isn't running. I think that it is deprecated in Rails 5 so that rules out that option.

我还尝试在我的API控制器中使用rescue_from:

I also tried to use rescue_from in my API Controller:

rescue_from JSON::ParserError, with: :json_error

def json_error
  render status: 400, json: {error: "Invalid JSON format in request body"}, status: :unprocessable_entity
end

但是，这也不起作用.似乎跳过了它.

However, this also did not work. It seems to skip past it.

或者，如果我尝试这样做:

Or if I try this:

rescue_from JSON::ParserError, with: json_error

def json_error
  render status: 400, json: {error: "Invalid JSON format in request body"}, status: :unprocessable_entity
end

我得到:

undefined local variable or method `json_error' for Api::ApiController:Class
actionpack (5.0.0.1) lib/action_dispatch/routing/route_set.rb, line 46

``` ruby
   41         private
   42   
   43           def controller(req)
   44             req.controller_class
   45           rescue NameError => e
>  46             raise ActionController::RoutingError, e.message, e.backtrace
   47           end
   48   
   49           def dispatch(controller, action, req, res)
   50             controller.dispatch(action, req, res)
   51           end

迷路了，可以使用一些指导

Getting very lost, could use some guidance

推荐答案

上面的指南似乎已与Rails 5一起过时.经过一番调查，似乎不再调用以下中间件:

Seems the guide above is outdated with Rails 5. After some investigation, it seems that the following middleware is no longer called:

config/application.rb

config.middleware.insert_before ActionDispatch::ParamsParser, "CatchJsonParseErrors"

我将其修改为:

require "./lib/middleware/catch_json_parse_errors.rb"
config.middleware.insert_before Rack::Head, CatchJsonParseErrors

这是因为Rack :: Head在中间件堆栈中，而ActionDispatch :: ParamsParser没有在中间件堆栈中.另外，不建议将类名"用作字符串，因此您需要先提供文件，然后再传入该类.

This is because Rack::Head is in the middleware stack, but ActionDispatch::ParamsParser is not. Also, the use of Class names as strings is deprecated, so you need to require the file and then pass in the class.

我还修改了以下类，以检查env ['CONTENT_TYPE']而不是env ['HTTP_ACCEPT']

I also modified the below class to check env['CONTENT_TYPE'] instead of env['HTTP_ACCEPT']

class CatchJsonParseErrors
  def initialize(app)
    @app = app
  end

  def call(env)
    begin
      @app.call(env)
    rescue ActionDispatch::ParamsParser::ParseError => error
      if env['CONTENT_TYPE'] =~ /application\/json/
        error_output = "There was a problem in the JSON you submitted: #{error.class}"
        return [
          400, { "Content-Type" => "application/json" },
          [ { status: 400, error: error_output }.to_json ]
        ]
      else
        raise error
      end
    end
  end
end

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