Write Headings Example

This example demonstrates how to write multiple heading lines by configuring field headings in metadata.

What it does

1. Deserializes metadata from an XML string
2. Sets meta.headingLineCount = 3 to output three heading rows
3. Assigns per-field heading arrays for Product, Quantity, and Price
4. Writes a sample record and shows the generated output

Running the example

npx tsx examples/write-headings/index.ts
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Expected output

==============================
Inventory,Inventory,Pricing
Product,Quantity,Unit Price
Name,Count,USD
Widget,10,$19.99
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Key concepts

• Heading line count: Controls how many heading rows are emitted
• Per-field headings: Each field can provide one heading value per heading row
• Writer header behavior: Headings are written automatically before the first record

Code

// Write Header Example
// Demonstrates manually writing heading lines

import {
  FtStringWriter,
  FtWriter,
  FtXmlMetaSerialization,
} from "@pbkware/fielded-text-web";

// Load metadata from XML string
const metaXml = `<?xml version="1.0" encoding="utf-8"?>
<FieldedText>
  <Field Name="Product" />
  <Field DataType="Integer" Name="Quantity" />
  <Field DataType="Decimal" Name="Price" Format="C2" />
</FieldedText>`;

const productFieldName = "Product";
const quantityFieldName = "Quantity";
const priceFieldName = "Price";

// Load metadata from XML
const meta = FtXmlMetaSerialization.deserialize(metaXml);

// Meta does not include any heading lines, so we set them here for the writer to use
meta.headingLineCount = 3;

// Get Meta fields
const productField = meta.fieldList.find(productFieldName);
const quantityField = meta.fieldList.find(quantityFieldName);
const priceField = meta.fieldList.find(priceFieldName);

// Set headings for each field
productField!.headings = ["Inventory", "Product", "Name"];
quantityField!.headings = ["Inventory", "Quantity", "Count"];
priceField!.headings = ["Pricing", "Unit Price", "USD"];

// Create writer
const textWriter = new FtStringWriter();
const writer = new FtWriter(meta, textWriter);

console.log("==============================");

// Write data
writer.fieldList.get(0).asString = "Widget";
writer.fieldList.get(1).asBigInt = BigInt(10);
writer.fieldList.get(2).asDecimal = 19.99;
writer.write(); // The write of first record will first write header (including headings), if header has not yet been written

console.log(textWriter.toString());
console.log();
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