Proper Currency Formatting in Golang

When working with currency formatting, it's essential to consider the specific requirements for each currency and language combination. Using golang.org/x/text/currency, you can easily format values based on local conventions. However, you may encounter some challenges in getting the desired output.

Using Currency Symbols

In your code, you use currency.Symbol to retrieve the currency symbol for the specified ISO code. However, when using this method without providing a language context, you might not get the expected separators or number formatting.

Incorporating Local Formats

Instead of attempting to manually create your format, you can leverage the display and message packages to automatically retrieve the appropriate format based on the language and region. Here's an example:

import (
    "fmt"

    "golang.org/x/text/currency"
    "golang.org/x/text/language"
    "golang.org/x/text/message"
)

func formatCurrency(value int64, currencyCode string, languageCode string) string {
    lang, _ := language.Parse(languageCode)
    p := message.NewPrinter(lang)

    unit, _ := currency.ParseISO(currencyCode)
    return p.Sprintf("%v%v", currency.Symbol(unit), float64(value))
}

This function takes in a value, currency code, and language code and returns a properly formatted currency string.

Handling Increment Units

Some currencies have a fixed increment unit, such as 5 or 10 cents. To account for this, you can use the number package to specify the increment:

import (
    "golang.org/x/text/currency"
    "golang.org/x/text/number"
)

func formatWithIncrement(value int64, currencyCode string, increment int) string {
    unit, _ := currency.ParseISO(currencyCode)
    scale, inc := currency.Cash.Rounding(unit)
    dec := number.Decimal(float64(value), number.Scale(scale), number.IncrementString(fmt.Sprintf("%.2f", float64(inc))))
    return fmt.Sprintf("%v%v", currency.Symbol(unit), dec)
}

By providing the language context, inferring the currency format from language codes, and considering increment units, you can create flexible and accurate currency formatting solutions in Golang using golang.org/x/text/currency.