Wrk POST 请求中， 图片转 base64 的工具函数无法调用是怎么回事？

wrk发起post请求，request body中有一个value要求传入图片的base64编码，网上找了一个图片转base64的lua 脚本，导入后，能够把图片转成base64，但wrk无法调用？把函数当成字符串了， 因为body传入的时候，本身就是字符串格式，怀疑把函数直接放进去当成字符串了，尝试把body`进行字符串加变量拼接，也没用，非常的尴尬啊，老哥们帮忙看看

-- post.lua require("ZZBase64") local files local img = "test.jpg" local file = io.open(img,"rb") files = file:read("*a") file:close() -- print(ZZBase64.encode(files)) 能够打印出正常编码后的值 wrk.method = "POST" wrk.headers["Content-Type"] = "application/json" wrk.body = '{ "data": [ { "image": { "base64": ZZBse64.encode(files) } }] }' respOnse= function(status, headers, body) print(status) end -- 接口返回 400， 提示 request 不正确，并且把 request 打印了出来，ZZBase64.encode(files)原样在里边 

Ctrl V 的 image to base64 lua

-- ZZBase64.lua ZZBase64 = {} local string = string ZZBase64.__code = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/', }; ZZBase64.__decode = {} for k,v in pairs(ZZBase64.__code) do ZZBase64.__decode[string.byte(v,1)] = k - 1 end function ZZBase64.encode(text) local len = string.len(text) local left = len % 3 len = len - left local res = {} local index = 1 for i = 1, len, 3 do local a = string.byte(text, i ) local b = string.byte(text, i + 1) local c = string.byte(text, i + 2) -- num = a<<16 + b<<8 + c local num = a * 65536 + b * 256 + c for j = 1, 4 do --tmp = num >> ((4 -j) * 6) local tmp = math.floor(num / (2 ^ ((4-j) * 6))) --curPos = tmp&0x3f local curPos = tmp % 64 + 1 res[index] = ZZBase64.__code[curPos] index = index + 1 end end if left == 1 then ZZBase64.__left1(res, index, text, len) elseif left == 2 then ZZBase64.__left2(res, index, text, len) end return table.concat(res) end function ZZBase64.__left2(res, index, text, len) local num1 = string.byte(text, len + 1) num1 = num1 * 1024 --lshift 10 local num2 = string.byte(text, len + 2) num2 = num2 * 4 --lshift 2 local num = num1 + num2 local tmp1 = math.floor(num / 4096) --rShift 12 local curPos = tmp1 % 64 + 1 res[index] = ZZBase64.__code[curPos] local tmp2 = math.floor(num / 64) curPos = tmp2 % 64 + 1 res[index + 1] = ZZBase64.__code[curPos] curPos = num % 64 + 1 res[index + 2] = ZZBase64.__code[curPos] res[index + 3] = "=" end function ZZBase64.__left1(res, index,text, len) local num = string.byte(text, len + 1) num = num * 16 tmp = math.floor(num / 64) local curPos = tmp % 64 + 1 res[index ] = ZZBase64.__code[curPos] curPos = num % 64 + 1 res[index + 1] = ZZBase64.__code[curPos] res[index + 2] = "=" res[index + 3] = "=" end function ZZBase64.decode(text) local len = string.len(text) local left = 0 if string.sub(text, len - 1) == "==" then left = 2 len = len - 4 elseif string.sub(text, len) == "=" then left = 1 len = len - 4 end local res = {} local index = 1 local decode = ZZBase64.__decode for i =1, len, 4 do local a = decode[string.byte(text,i )] local b = decode[string.byte(text,i + 1)] local c = decode[string.byte(text,i + 2)] local d = decode[string.byte(text,i + 3)] --num = a<<18 + b<<12 + c<<6 + d local num = a * 262144 + b * 4096 + c * 64 + d local e = string.char(num % 256) num = math.floor(num / 256) local f = string.char(num % 256) num = math.floor(num / 256) res[index ] = string.char(num % 256) res[index + 1] = f res[index + 2] = e index = index + 3 end if left == 1 then ZZBase64.__decodeLeft1(res, index, text, len) elseif left == 2 then ZZBase64.__decodeLeft2(res, index, text, len) end return table.concat(res) end function ZZBase64.__decodeLeft1(res, index, text, len) local decode = ZZBase64.__decode local a = decode[string.byte(text, len + 1)] local b = decode[string.byte(text, len + 2)] local c = decode[string.byte(text, len + 3)] local num = a * 4096 + b * 64 + c local num1 = math.floor(num / 1024) % 256 local num2 = math.floor(num / 4) % 256 res[index] = string.char(num1) res[index + 1] = string.char(num2) end function ZZBase64.__decodeLeft2(res, index, text, len) local decode = ZZBase64.__decode local a = decode[string.byte(text, len + 1)] local b = decode[string.byte(text, len + 2)] local num = a * 64 + b num = math.floor(num / 16) res[index] = string.char(num) end