Lua Requires Chilkat v11.7.0+

Replace the Value After a Label in a PDF (Re-issue an Invoice)

See more PDF Text Replacement Examples

Demonstrates replacing the values that follow labels such as "Invoice Number:" on a PDF that has no placeholders -- an ordinary invoice. Each entry of the "labels" array names a label as it appears on the page and the new value; the value replaces the rest of the label's line. Label matching ignores case, extra spaces and a trailing colon. The replaced text is read back with ExtractText to confirm it. Lua

local chilkat = require("chilkat")

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

-- The PDF used in this example is available at invoice_labels.pdf

local pdf = chilkat.Pdf.new()
local success = pdf:load_file("qa_data/pdf/invoice_labels.pdf")
if not success then
    print(pdf.last_error_text)
    return
end

-- The invoice has lines such as "Invoice Number:   INV-2026-0412" and "Total Due:  $1,234.53".
-- Each label's new value replaces whatever follows the label on its line.
local json = chilkat.JsonObject.new()
json:update_string("labels[0].label", "Invoice Number:")
json:update_string("labels[0].value", "INV-2026-0500")
json:update_string("labels[1].label", "Invoice Date:")
json:update_string("labels[1].value", "April 2, 2026")
json:update_string("labels[2].label", "customer")
json:update_string("labels[2].value", "Contoso Ltd")
json:update_string("labels[3].label", "Total Due:")
json:update_string("labels[3].value", "$1,999.99")

local jsonOut = chilkat.JsonObject.new()
success = pdf:text_replace("apply", json, jsonOut)
if not success then
    print("Not applied: " .. jsonOut:emit())
    if not success then
        print(pdf.last_error_text)
        return
    end
end

local i = 0
local count_i = jsonOut:size_of_array("replacements")
while i < count_i do
    jsonOut.i = i
    print("Replaced the value of \"" .. jsonOut:string_of("replacements[i].label") .. "\" on page " .. jsonOut:string_of("replacements[i].pages"))
    i = i + 1
end

success = pdf:write_file("qa_output/invoice_reissued.pdf")
if not success then
    print(pdf.last_error_text)
    return
end

-- Read the new values back with ExtractText's label option.
local jsonRead = chilkat.JsonObject.new()
local jsonText = chilkat.JsonObject.new()
jsonRead:update_string("label", "Total Due")
jsonRead:update_string("labelValue", "right")
success = pdf:extract_text("text", jsonRead, jsonText)
if not success then
    print(pdf.last_error_text)
    return
end

print("Total Due is now: " .. jsonText:string_of("text"))

-- Sample output:

-- Replaced the value of "Invoice Number:" on page 1
-- Replaced the value of "Invoice Date:" on page 1
-- Replaced the value of "customer" on page 1
-- Replaced the value of "Total Due:" on page 1
-- Total Due is now: $1,999.99