Context

Context is a class which contains the Request, Response structures of an HTTP server, since Crystal Language allows us to extend its core features we have decided to add couple of helper functions to the context class.

Available methods¶

exec/0 delete_req_header/1 delete_resp_header/1 get_req_header/1 get_resp_header/1 halt/0 merge_resp_headers/1 put_req_header/2 put_resp_header/2 put_resp_cookie/2 put_status/1 send_file/1 send_resp/1 json/2 html/2 text/2 binary/2 fetch_json_params/0 fetch_query_params/0 fetch_body_params/0 fetch_file_params/0 fetch_path_params/0

exec¶

Run a block in the context scope.

def get(context : Context)
  context.exec do
    put_status(201) # Put a response status code.
    put_resp_header("Server", "TornadoServer/6.0.4") # Put a response header.
    json( # Respond with JSON encoded data.
      {
        "id" => 1
      }
    )
  end
end

delete_req_header¶

Deletes a request header if present.

def get(context : Context) : Context
  context
    .delete_req_header("Referer")
    .text(nil)
end

delete_resp_header¶

Deletes a response header if present.

def get(context : Context) : Context
  context
    .json("Hello, World!")
    .delete_resp_header("Content-Type")
end

get_req_header¶

Returns the values of the request header specified by key.

def get(context : Context) : Context
  referer =
    context
      .get_req_header("Referer")

  context
    .json(
      {
        "referer" => referer
      }
    )
end

get_resp_header¶

Returns the values of the response header specified by key.

def get(context : Context) : Context
  content_type =
    context
      .get_resp_header("Content-Type")

  context
    .json(
      {
        "contentType" => content_type
      }
    )
end

halt¶

Halts the function chain by closing the response stream.

def get(context : Context) : Context
  context
    .json("Hello, World!")
    .halt
end

merge_resp_headers¶

Merges a series of response headers into the context.

def get(context : Context) : Context
  context
    .merge_resp_headers({"Content-Type" => "application/json"})
    .send_resp("Hello, World!")
end

put_req_header¶

Adds a new request header (key) if not present, otherwise replaces the previous value of that header with value.

def get(context : Context) : Context
  context
    .put_req_header("Referer", "www.google.com")
    .json("Hello, World")
end

put_resp_header¶

Adds a new response header (key) if not present, otherwise replaces the previous value of that header with value.

def get(context : Context) : Context
  context
    .put_resp_header("Content-Type", "application/json")
    .send_resp("Hello, World!")
end

put_resp_cookie¶

Adds a new cookie to the response. If the cookie already exists it will be overwritten.

def get(context : Context) : Context
  context
    .put_resp_cookie("MyCookie", "Cookie Value") # Or .put_resp_cookie(HTTP::Cookie.new("MyCookie", "Cookie Value"))
    .send_resp("Hello, World!")
end

put_status¶

Assigns the given status code to the context response.

def get(context : Context) : Context
  context
    .put_status(400)
    .json("Bad request")
end

send_file¶

Sends a file to the client.

def get(context : Context) : Context
  context
    .send_file("./example.txt")
end

send_resp¶

Sends a response to the client.

def get(context : Context) : Context
  context
    .send_resp("Hello, World!")
end

json¶

Sends JSON response.

The function has an optional second argument for the Content-Type header.

def get(context : Context) : Context
  context
    .json("Hello, World!", "application/json; charset=UTF-8")
end

html¶

Sends HTML response.

The function has an optional second argument for the Content-Type header.

def get(context : Context) : Context
  context
    .html("Hello, World!")
end

text¶

Sends text response.

The function has an optional second argument for the Content-Type header.

def get(context : Context) : Context
  context
    .text("Hello, World!")
end

binary¶

Sends binary response.

The function has an optional second argument for the Content-Type header.

def get(context : Context) : Context
  context
    .binary("Hello, World!")
end

fetch_json_params¶

Fetches JSON parameters from the JSON parser.

def get(context : Context) : Context
  params =
    context
      .fetch_json_params

  context
    .json(params)
end

fetch_query_params¶

Fetches query parameters from the query string.

def get(context : Context) : Context
  params =
    context
      .fetch_query_params

  context
    .json(params)
end

fetch_body_params¶

Fetches body parameters from the body parser.

def get(context : Context) : Context
  params =
    context
      .fetch_body_params

  context
    .json(params)
end

fetch_file_params¶

Fetches file parameters from the file parser.

def get(context : Context) : Context
  params =
    context
      .fetch_file_params

  context
    .json(params)
end

fetch_path_params¶

Fetches path parameters from the path parser.

def get(context : Context) : Context
  params =
    context
      .fetch_path_params

  context
    .json(params)
end