Http С；奥帕斯。在请求中传递头并选择请求方法

我将copas库用于非阻塞请求。 我遇到了一个问题。我不明白如何传递下面的标题：“Content-Type:application/json”，我还想在POST和GET方法之间切换，这是如何做到的

我的代码：

功能：

function httpRequest(request, body, handler) 
        if not copas.running then
            copas.running = true
            lua_thread.create(function()
                wait(0)
                while not copas.finished() do
                    local ok, err = copas.step(0)
                    if ok == nil then error(err) end
                    wait(0)
                end
                copas.running = false
            end)
        end
        -- do request
        if handler then
            return copas.addthread(function(r, b, h)
                copas.setErrorHandler(function(err) h(nil, err) end)
                h(http.request(r, b))
            end, request, body, handler)
        else
            local results
            local thread = copas.addthread(function(r, b)
                copas.setErrorHandler(function(err) results = {nil, err} end)
                results = table.pack(http.request(r, b))
            end, request, body)
            while coroutine.status(thread) ~= 'dead' do wait(0) end
            return table.unpack(results)
        end
    end

用法示例：

httpRequest("https://sampmulti.azurewebsites.net/get/last_message", nil, function(response, code, headers, status)
        if response then
            local data = json.decode(response)
            last_message= data["last_message"]
            print("last_message: ", last_message)
        else
            print('Error', code)
        end
    end)

我怎样才能对标题和方法POST或GET执行相同的操作

我也阅读了文档，但不明白如何做到这一点。

---

copas.http请求应与兼容

尝试以下示例，该示例将使用一些自定义标题发布到httpbin.org：

local copas = require "copas"
local http = require "copas.http"
local ltn12 = require "ltn12" -- needed to process the streams


function doRequest()
  local reqbody = "isThisAGreatExample=true"

  local respbody = {}
  local  ok, code, headers, status = http.request {
    method = "POST",
    url = "https://httpbin.org/post",
    source = ltn12.source.string(reqbody),
    headers =
    {
      ["Accept"] = "*/*",
      ["Accept-Encoding"] = "gzip, deflate",
      ["Accept-Language"] = "en-us",
      ["Content-Type"] = "application/x-www-form-urlencoded",
      ["content-length"] = string.len(reqbody)
    },
    sink = ltn12.sink.table(respbody)
  }

  print('ok:' .. tostring(ok))
  print('code:' .. tostring(code))
  print('body:' .. table.concat(respbody))
end

copas.addthread(doRequest)
copas.loop()