Print out only headers in Rails request

Question

I know how to access a header in Rails

request.headers["HEADER_NAME"] 

However, I want to get all headers passed by a browser. I see that I can enumerate it

request.headers.each { |header| ... } 

However, this will spit out both headers and other environment variables. Is there a way to get only headers?

Update 1

My problem isn't interation. My problem is distinguising between environment variables and headers. Both of them will be reported while interation using each or keys.

Answer 1

Solution

By convention, headers do not usually contain dots. Nginx even rejected requests with dots in headers by default. So I think it's quite a safe assumption to go with.

On contrary, all rails environment garbage is namespaced e.g. action_dispatch.show_exceptions, rack.input etc.

These two facts conveniently suggest a way to distinguish external headers from internal variables:

request.headers.env.reject { |key| key.to_s.include?('.') } 

Works neat.

---

Benchmarking a bit

Note, that include?('.') implementation works about 4 times faster than matching =~ /\./

Benchmark.measure { 500000.times { hsh.reject { |key| key.to_s =~ /\./ } } }  => real=2.09 Benchmark.measure { 500000.times { hsh.reject { |key| key.to_s.include?('.') } } }  => real=0.58 

Hope that helps.

Answer 2

By using

request.headers.each { |key, value|  } 

This is iterating your requested header with (key+value), but if you want specific values you have to use key name like, HTTP_KEYNAME because whenever HTTP request come it will append HTTP to keys and be sure about uppercase because it is case sensitive.

for example:

if we have passed auth_token as header request parameter and want to access, we can use this.

request.headers["HTTP_AUTH_TOKEN"]