Basic Read Example

This example demonstrates reading a CSV file with the Node.js FieldedText library while loading metadata from a local XML file.

What it does

1. Loads field metadata from the local meta.ftm file using FtNodeXmlMetaSerialization
2. Opens the local CSV file with FtNodeFileReader
3. Reads records using field ordinals
4. Displays typed field values and the total record count

Running the example

npm run node-basic-read
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The command should be run from the examples directory. The example reads basic-read-example.csv from this directory and reports the file path after processing.

Node-specific APIs

• FtNodeXmlMetaSerialization: Loads the XML metadata from a file.
• FtNodeFileReader: Reads fielded text directly from a file path.
• Field ordinals: getFieldIndexByName() provides efficient typed field access.

// Basic Read Example
// Demonstrates reading CSV data with metadata loaded from XML

import {
  FtNodeFileReader,
  FtNodeXmlMetaSerialization,
} from "@pbkware/fielded-text-node";
import * as path from "node:path";
import { fileURLToPath } from "node:url";

// Get directory path for ESM module
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

// Names of files containing the data and metadata
const csvFileName = "basic-read-example.csv";
const metaFileName = "meta.ftm";
const csvFilePath = path.join(__dirname, csvFileName);
const metaFilePath = path.join(__dirname, metaFileName);

// Define field names
const PetNameFieldName = "PetName";
const AgeFieldName = "Age";
const ColorFieldName = "Color";
const DateReceivedFieldName = "DateReceived";
const PriceFieldName = "Price";
const NeedsWalkingFieldName = "NeedsWalking";
const TypeFieldName = "Type";

// Load metadata from XML
console.log("Loading metadata from XML...");
const meta = FtNodeXmlMetaSerialization.deserializeFromFile(metaFilePath);

console.log(`Loaded metadata with ${meta.fieldList.count} fields\n`);

// Create reader and read CSV (automatically closed when it goes out of scope)
using reader = new FtNodeFileReader(csvFilePath, meta);

console.log("Reading CSV data:");
console.log("================\n");

// Get field ordinals for faster access (compared to calling getFieldByName() for each record)
const petNameFieldOrdinal = reader.getFieldIndexByName(PetNameFieldName)!;
const ageFieldOrdinal = reader.getFieldIndexByName(AgeFieldName)!;
const colorFieldOrdinal = reader.getFieldIndexByName(ColorFieldName)!;
const dateReceivedFieldOrdinal = reader.getFieldIndexByName(
  DateReceivedFieldName,
)!;
const priceFieldOrdinal = reader.getFieldIndexByName(PriceFieldName)!;
const needsWalkingFieldOrdinal = reader.getFieldIndexByName(
  NeedsWalkingFieldName,
)!;
const typeFieldOrdinal = reader.getFieldIndexByName(TypeFieldName)!;

let recordNumber = 0;
while (reader.read()) {
  recordNumber++;

  const petName = reader.fieldList.get(petNameFieldOrdinal).asString;
  const age = reader.fieldList.get(ageFieldOrdinal).asNullableFloat;
  const color = reader.fieldList.get(colorFieldOrdinal).asString;
  const dateReceived = reader.fieldList.get(
    dateReceivedFieldOrdinal,
  ).asDateTime;
  const price = reader.fieldList.get(priceFieldOrdinal).asDecimal;
  const needsWalking = reader.fieldList.get(needsWalkingFieldOrdinal).asBoolean;
  const type = reader.fieldList.get(typeFieldOrdinal).asString;

  console.log(
    `${recordNumber}: ${petName}, ${age} years, ${color}, received ${dateReceived.toLocaleDateString()}, $${price}, walks: ${needsWalking}, ${type}`,
  );
}

console.log(`\nTotal records read: ${recordNumber}`);
console.log(`Input read from: ${csvFilePath}`);
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