Context

The Context class in the Grip module provides a set of helper methods to simplify HTTP request and response handling in a Crystal-based HTTP server. These methods enable fluent manipulation of headers, cookies, status codes, and response content, with most returning self for method chaining.

Available Methods¶

exec/0
delete_req_header/1
delete_resp_header/1
get_req_header/1
get_req_header?/1
get_req_cookie/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
redirect/2

exec¶

Run a block in the context scope, allowing chained operations.

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 by key if present. Returns self for method chaining.

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

delete_resp_header¶

Deletes a response header by key if present. Returns self for method chaining.

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

get_req_header¶

Returns the value of the request header specified by key. Raises KeyError if not found.

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

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

get_req_header?¶

Returns the value of the request header specified by key, or nil if not found.

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

  context
    .json(
      {
        "referer" => referer || "No Referer"
      }
    )
end

get_req_cookie¶

Returns the cookie from the request specified by key, or nil if not found.

def get(context : Context) : Context
  cookie =
    context
      .get_req_cookie("MyCookie")

  context
    .json(
      {
        "cookie" => cookie.try(&.value) || "No Cookie"
      }
    )
end

get_resp_header¶

Returns the value of the response header specified by key. Raises KeyError if not found.

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. Returns self for method chaining.

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

merge_resp_headers¶

Merges a series of response headers into the context. Returns self for method chaining.

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

put_req_header¶

Adds or replaces a request header with the given key and value. Returns self for method chaining.

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

put_resp_header¶

Adds or replaces a response header with the given key and value. Returns self for method chaining.

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

put_resp_cookie¶

Adds or overwrites a response cookie. Accepts either a key-value pair or an HTTP::Cookie object. Returns self for method chaining.

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. Accepts either an HTTP::Status or an Int32. Returns self for method chaining.

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

send_file¶

Sends a file to the client. The path must point to an existing file. Optionally specify mime_type (inferred from extension if nil) and enable gzip_enabled for compression. Returns self for method chaining.

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

send_resp¶

Sends a response to the client with the given content. Returns self for method chaining.

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

json¶

Sends a JSON response. Optionally specify the Content-Type header. Returns self for method chaining.

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

html¶

Sends an HTML response. Optionally specify the Content-Type header. Returns self for method chaining.

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

text¶

Sends a text response. Optionally specify the Content-Type header. Returns self for method chaining.

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

binary¶

Sends a binary response. Accepts a string or Bytes. Optionally specify the Content-Type header. Returns self for method chaining.

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

fetch_json_params¶

Fetches JSON parameters from the request body. Returns an empty hash if no parameters are available.

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

  context
    .json(params)
end

fetch_query_params¶

Fetches query parameters from the URL query string. Returns an empty URI::Params if no parameters are available.

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

  context
    .json(params)
end

fetch_body_params¶

Fetches URL-encoded body parameters from the request. Returns an empty URI::Params if no parameters are available.

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

  context
    .json(params)
end

fetch_file_params¶

Fetches multipart file parameters from the request. Returns an empty hash if no parameters are available.

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

  context
    .json(params)
end

fetch_path_params¶

Fetches path parameters from the URL. Returns an empty hash if no parameters are available.

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

  context
    .json(params)
end

redirect¶

Redirects the response to the specified url with a given status code (default 302 Found). Accepts either an HTTP::Status or an Int32. Returns self for method chaining.

def get(context : Context) : Context
  context
    .redirect("/new-page", 302)
end