Print out only headers in Rails request - ruby-on-rails

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"]

Answer 3

You can try this to get only headers list from request
request.headers.first(50).to_h.keys
It will convert request.headers object into array and then to hash to get list of all keys in request to be used as
request.headers["keyname"]
It might be not much efficient but I think it can do the job.
Hope this helps.

Answer 4

not sure if this is any helpful but I ended up using this brute force approach
request.env.select {|k,v|
k.match("^HTTP.*|^CONTENT.*|^REMOTE.*|^REQUEST.*|^AUTHORIZATION.*|^SCRIPT.*|^SERVER.*")
}

Answer 5

You might be probably looking for :
request.env
This will basically create a Ruby Hash of the whole request object.
For more details, check this question:
How do I see the whole HTTP request in Rails

Answer 6

If you just want headers:
request.headers.to_h.select { |k,v|
['HTTP','CONTENT','AUTHORIZATION'].any? { |s| k.to_s.starts_with? s }
}
If you want everything that's not an env var:
request.headers.to_h.select { |k,v|
['HTTP','CONTENT','REMOTE','REQUEST','AUTHORIZATION','SCRIPT','SERVER'].any? { |s|
k.to_s.starts_with? s
}
}

Answer 7

You should be able to do
request.headers.each { |key, value| }
In general when iterating over a hash ruby looks at the arity of your block and gives you either a pair (key + value) or separate variables. (The hash in this case is an object internal to the headers object)