Zig Requires Chilkat v11.7.0+

Fill a PDF Template: Replace {{placeholders}} with Values

See more PDF Text Replacement Examples

Demonstrates the TextReplace method on an invoice template whose values are written as placeholders such as {{customer}} and {{total}}. The "placeholders" object names each placeholder and the text to put in; every occurrence on the page is replaced, including a placeholder inside a sentence or inside a label such as "Tax ({{taxRate}}):". The text is redrawn with the font the template used, so the result looks like the template, and a value that is right-aligned in the template stays right-aligned. The changes are written by WriteFile. Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    var success: bool = false;

    // 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_template.pdf

    const pdf = try chilkat.Pdf.init();
    defer pdf.deinit();
    success = if (pdf.loadFile("qa_data/pdf/invoice_template.pdf")) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try pdf.getLastErrorText(alloc)});
        return;
    }

    // The template has these placeholders in its page text:
    //   {{customer}} (twice: "Bill To:" and the closing sentence), {{date}}, {{po}},
    //   two item rows: {{qty1}} {{desc1}} {{price1}} {{amount1}} and {{qty2}} {{desc2}} {{price2}} {{amount2}},
    //   {{subtotal}}, "Tax ({{taxRate}}):" with {{tax}}, and {{total}}.
    const json = try chilkat.JsonObject.init();
    defer json.deinit();
    json.updateString("placeholders.customer", "Acme Corp") catch {};
    json.updateString("placeholders.date", "2026-10-18") catch {};
    json.updateString("placeholders.po", "PO-88213") catch {};
    json.updateString("placeholders.qty1", "2") catch {};
    json.updateString("placeholders.desc1", "Cordless drill, 18 V") catch {};
    json.updateString("placeholders.price1", "$460.00") catch {};
    json.updateString("placeholders.amount1", "$920.00") catch {};
    json.updateString("placeholders.qty2", "6") catch {};
    json.updateString("placeholders.desc2", "Galvanized hinge, 4 inch") catch {};
    json.updateString("placeholders.price2", "$12.50") catch {};
    json.updateString("placeholders.amount2", "$75.00") catch {};
    json.updateString("placeholders.subtotal", "$995.00") catch {};
    json.updateString("placeholders.taxRate", "7.35%") catch {};
    json.updateString("placeholders.tax", "$73.13") catch {};
    json.updateString("placeholders.total", "$1,068.13") catch {};

    // "apply" makes every replacement, or none: if any value cannot be drawn with the
    // template's font, the method returns false, the PDF is unchanged, and jsonOut says why.
    const json_out = try chilkat.JsonObject.init();
    defer json_out.deinit();
    success = if (pdf.textReplace("apply", json, json_out)) true else |_| false;
    if (!success) {
        std.debug.print("Not applied: {s}\n", .{try json_out.emit(alloc)});
        if (!success) {
            std.debug.print("{s}\n", .{try pdf.getLastErrorText(alloc)});
            return;
        }
    }

    // One entry per placeholder: the pages it was found on and how many times it was replaced.
    var i: i32 = 0;
    const count_i = json_out.sizeOfArray("replacements");
    while (i < count_i) {
        json_out.setI(i);
        std.debug.print("{s}: {d} on page(s) {s}\n", .{ try json_out.stringOf(alloc, "replacements[i].field"), json_out.intOf("replacements[i].count"), try json_out.stringOf(alloc, "replacements[i].pages") });
        i = i + 1;
    }

    // The replacements stay in memory until the PDF is written.
    pdf.writeFile("qa_output/invoice_filled.pdf") catch {
        std.debug.print("{s}\n", .{try pdf.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("Wrote qa_output/invoice_filled.pdf\n", .{});

    // Sample output:

    // customer: 2 on page(s) 1
    // date: 1 on page(s) 1
    // po: 1 on page(s) 1
    // qty1: 1 on page(s) 1
    // desc1: 1 on page(s) 1
    // price1: 1 on page(s) 1
    // amount1: 1 on page(s) 1
    // qty2: 1 on page(s) 1
    // desc2: 1 on page(s) 1
    // price2: 1 on page(s) 1
    // amount2: 1 on page(s) 1
    // subtotal: 1 on page(s) 1
    // taxRate: 1 on page(s) 1
    // tax: 1 on page(s) 1
    // total: 1 on page(s) 1
    // Wrote qa_output/invoice_filled.pdf
}