Lua Requires Chilkat v11.7.0+

Handle QR Code Errors

See more QR Code Examples

Demonstrates what happens when a request is refused. QrCode returns false and the response holds errors[0] with three members: a code that does not change between versions, the path of the request member at fault (a JSON Pointer such as /encoding/qr/version), and a message. Requests are checked strictly, so a misspelled option is an error rather than being silently ignored. LastErrorText has the same information in more detail. Lua

local chilkat = require("chilkat")

-- This example requires the Chilkat API to have been previously unlocked.
-- See Global Unlock Sample for sample code.

local fmt = chilkat.Formats.new()
local json = chilkat.JsonObject.new()
local jsonOut = chilkat.JsonObject.new()

-- 1. A misspelled option: "moduleSise" for "moduleSize".
json:update_string("payload.text", "https://www.chilkatsoft.com/")
json:update_int("render.moduleSise", 8)
local success = fmt:qr_code("generate", json, jsonOut)
if not success then
    print("code: " .. jsonOut:string_of("errors[0].code"))
    print("path: " .. jsonOut:string_of("errors[0].path"))
    print("message: " .. jsonOut:string_of("errors[0].message"))
end

-- 2. A value out of range: QR versions are 1 to 40.
json:clear()
json:update_string("payload.text", "https://www.chilkatsoft.com/")
json:update_int("encoding.qr.version", 41)
success = fmt:qr_code("generate", json, jsonOut)
if not success then
    print("code: " .. jsonOut:string_of("errors[0].code"))
    print("path: " .. jsonOut:string_of("errors[0].path"))
    print("message: " .. jsonOut:string_of("errors[0].message"))
end

-- 3. Too much data: this text does not fit a version 1 symbol.
json:clear()
json:update_string("payload.text", "https://www.chilkatsoft.com/barcode_overview.asp")
json:update_int("encoding.qr.version", 1)
success = fmt:qr_code("generate", json, jsonOut)
if not success then
    print("code: " .. jsonOut:string_of("errors[0].code"))
    print("path: " .. jsonOut:string_of("errors[0].path"))
    print("message: " .. jsonOut:string_of("errors[0].message"))
end

-- A program can act on the code.
if jsonOut:string_of("errors[0].code") == "capacityExceeded" then
    print("The text is too long for the symbol size allowed.")
end

-- Sample output:

-- code: unknownOption
-- path: /render/moduleSise
-- message: unknown option
-- code: outOfRange
-- path: /encoding/qr/version
-- message: the value is out of range
-- code: capacityExceeded
-- path: /payload
-- message: the payload does not fit the requested QR version at the requested error-correction level
-- The text is too long for the symbol size allowed.