?:0: attempt to perform arithmetic on field 'fileSize' (a nil value) - lua

Question

How to resolved error or possible ways to resolved it?
Guys, i've developed plugin using Lua language which can be integrate or run from Adobe's LightRoom Classic. Currently i need to upload or send a file to server but i can not. Everytime i called the POST API which is multipart/form-data error popup "?:0: attempt to perform arithmetic on field 'fileSize' (a nil value)". Not even API is being called this error pops up before API call. after debug I can assure the possible issue is in creating mimeChunks with file type.
I have developed the code like below, can any one help me out with suggestions so that i can able to resolved issue?
local filePath = assert("C:\Users\Ankit\Desktop\Hangman.PNG")
local fileName = LrPathUtils.leafName(filePath)
local mimeChunks = {}
mimeChunks[#mimeChunks + 1] = {
name = 'api_sig',
value = "test value"
}
mimeChunks[#mimeChunks + 1] = {
name = "file",
filePath = filePath,
fileName = fileName,
contentType = "application/octet-stream"
}
local postUrl = "API endpoint"
local result, hdrs = LrHttp.postMultipart(postUrl, mimeChunks)
if result then
LrDialogs.message("Form Values", result)
else
LrDialogs.message("Form Values", "API issue")
end

Answer 1

Eventually image or file path itself cause the issue, there are no such indications or articles related to this functionality, but yes "add-on backslash" will work out for sure. Kindly review the below code for more detailed bifurcation which pass dynamic selected file or image path.
local function uploadFile(filePath)
local fileName = LrPathUtils.leafName( filePath )
local mimeChunks = {}
mimeChunks[ #mimeChunks + 1 ] = { name = 'api_sig', value = "test value"}
mimeChunks[#mimeChunks + 1] = {
name = "file",
filePath = filePath,
fileName = fileName,
contentType = "image/jpeg" --multipart/form-data --application/octet-stream
}
import "LrTasks".startAsyncTask(
function()
local postUrl = "http://cms.local.com/api/v1/upload"
local result, hdrs = LrHttp.postMultipart(postUrl, mimeChunks)
if result then
LrDialogs.message("Image uploaded.", result)
else
LrDialogs.message("Error", "API issue")
end
end
)
end
Above uploadFile method will automatically call the API and post form-data collection. Below code is for call uploadFile function which select all the images from catalog.
for p, photo in ipairs(LrApplication.activeCatalog()) do
uploadFile(assert(photo:getRawMetadata('path')));
end
Above code will help you out the selection of categlog with Adobe's LightRoom Plugin.