This plugin automatically converts currency values from a source currency to a target currency for records within a Flatfile Sheet. It utilizes the Open Exchange Rates API to fetch both the latest and historical exchange rates. The primary use case is for processing financial data, such as transaction logs or expense reports, where amounts need to be standardized into a single currency. The plugin can use a date from another field in the record to fetch the correct historical rate for the conversion. It can optionally store the calculated exchange rate and the date of conversion back into the record. The plugin operates by hooking into the record processing lifecycle, making it a seamless part of the data import process.

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Installation

Install the plugin using npm: 
npm install @flatfile/plugin-convert-currency

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Configuration & Parameters

The plugin requires a configuration object with the following parameters:

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Required Parameters

ParameterTypeDescription
sheetSlugstringThe slug of the sheet the plugin should operate on
sourceCurrencystringThe three-letter currency code (e.g., “USD”) of the source amounts
targetCurrencystringThe three-letter currency code (e.g., “EUR”) to convert the amounts to
amountFieldstringThe field key/slug that contains the numerical amount to be converted
convertedAmountFieldstringThe field key/slug where the converted amount will be stored

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Optional Parameters

ParameterTypeDescriptionDefault Behavior
dateFieldstringThe field key/slug containing the date (in YYYY-MM-DD format) for fetching historical exchange ratesUses current date to fetch latest exchange rates
exchangeRateFieldstringThe field key/slug where the calculated exchange rate for the conversion will be storedExchange rate is not stored on the record
conversionDateFieldstringThe field key/slug where the timestamp of the conversion will be stored in ISO formatConversion date is not stored on the record

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Usage Examples

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Basic Usage

import { FlatfileListener } from "@flatfile/listener";
import { currencyConverterPlugin } from "@flatfile/plugin-convert-currency";

export default function (listener) {
  listener.use(
    currencyConverterPlugin({
      sheetSlug: "transactions",
      sourceCurrency: "USD",
      targetCurrency: "EUR",
      amountField: "amount",
      convertedAmountField: "amountInEUR",
    })
  );
}

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Full Configuration with Historical Rates

import { FlatfileListener } from "@flatfile/listener";
import { currencyConverterPlugin } from "@flatfile/plugin-convert-currency";

export default function (listener) {
  listener.use(
    currencyConverterPlugin({
      sheetSlug: "transactions",
      sourceCurrency: "USD",
      targetCurrency: "EUR",
      amountField: "amount",
      dateField: "transactionDate",
      convertedAmountField: "amountInEUR",
      exchangeRateField: "exchangeRate",
      conversionDateField: "conversionDate",
    })
  );
}

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Using Utility Functions

import { 
  validateAmount, 
  validateDate, 
  convertCurrency, 
  calculateExchangeRate 
} from "@flatfile/plugin-convert-currency";

// Validate an amount
const amountResult = validateAmount(150.75);
// Returns: { value: 150.75 }

// Validate a date
const dateResult = validateDate('2023-10-27');
// Returns: { value: '2023-10-27' }

// Convert currency
const converted = convertCurrency(100, 0.92, 1.0);
// Returns: 108.6957

// Calculate exchange rate
const rate = calculateExchangeRate(0.92, 0.80);
// Returns: 0.869565

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Troubleshooting

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Common Error Messages

ErrorCauseSolution
”Invalid source/target currency”Currency codes are not valid three-letter codesCheck that currency codes are valid and supported by the API
”Network error” or “Status: 401”API key issuesVerify OPENEXCHANGERATES_API_KEY is correct and not expired
”Amount must be a valid number”Invalid amount dataEnsure amount field contains numeric values
”Invalid date format”Date not in YYYY-MM-DD formatEnsure date field uses YYYY-MM-DD format

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Error Handling

The plugin handles errors gracefully by attaching them directly to records in Flatfile:
  • Validation errors: Attached to specific fields using record.addError(fieldName, message)
  • API/Network errors: Attached as general record errors using record.addError('general', message)

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Notes

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Requirements

  • An active subscription to the Open Exchange Rates API is required
  • The OPENEXCHANGERATES_API_KEY environment variable must be set in your Flatfile Space with your API key

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Limitations

  • All currency conversions are routed through USD as a base currency due to Open Exchange Rates API limitations on free/lower-tier plans
  • The dateField must contain dates in YYYY-MM-DD format only
  • Converted amounts are fixed to 4 decimal places
  • Exchange rates are fixed to 6 decimal places

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Default Behavior

  • When dateField is not provided, the plugin uses the current date to fetch the latest exchange rates
  • When exchangeRateField is not provided, the calculated exchange rate is not stored on the record
  • When conversionDateField is not provided, the conversion timestamp is not stored on the record
  • Empty date fields default to the current date in YYYY-MM-DD format