How to Fix Currency Formatting Issues in Go Using golang.org/x/text/currency

Currency Formatting with golang.org/x/text/currency

When formatting values as currency in Go, the golang.org/x/text/currency package provides a convenient solution. However, if the output appears without commas or thousands separators, this article explores the potential causes and solutions.

Incorrect Formatting: Points vs. Commas

In the provided code, the issue arises from using currency.Symbol directly instead of employing the more comprehensive formatting provided by message.NewPrinter. The correct approach is to use message.NewPrinter to handle the appropriate language-specific formatting:

<code class="go">func (produto *Produto) FormataPreco(valor int64) string {
    unit, _ := currency.ParseISO("BRL")
    p := message.NewPrinter(language.BrazilianPortuguese)
    return p.Sprint(unit.Amount(float64(valor) / 100))
}</code>

System Locale Resources

To format currency using system locale resources, the solution requires inferring the format from the language code. This can be achieved using display.Tags:

<code class="go">n := display.Tags(language.English)
for _, lcode := range []string{&quot;en_US&quot;, &quot;pt_BR&quot;, &quot;de&quot;, &quot;ja&quot;, &quot;hi&quot;} {
    lang := language.MustParse(lcode)
    cur, _ := currency.FromTag(lang)
    scale, _ := currency.Cash.Rounding(cur) // fractional digits
    dec := number.Decimal(100000.00, number.Scale(scale))
    p := message.NewPrinter(lang)
    p.Printf(&quot;%24v (%v): %v%v\n&quot;, n.Name(lang), cur, currency.Symbol(cur), dec)
}</code>

Alternatively, ISO currency codes can be parsed, but the output language must be specified separately:

<code class="go">for _, iso := range []string{&quot;USD&quot;, &quot;BRL&quot;, &quot;EUR&quot;, &quot;JPY&quot;, &quot;INR&quot;} {
    cur := currency.MustParseISO(iso)
    scale, _ := currency.Cash.Rounding(cur) // fractional digits
    dec := number.Decimal(100000.00, number.Scale(scale))
    p := message.NewPrinter(language.English)
    p.Printf(&quot;%v: %v%v\n&quot;, cur, currency.Symbol(cur), dec)
}</code>

Rounding Requirements

Certain currencies necessitate rounding in increments (e.g., 0.05 or 0.50). To accommodate this, additional processing is required to provide the correct IncrementString to the Decimal formatter:

<code class="go">scale, incCents := currency.Cash.Rounding(cur) // fractional digits
incFloat := math.Pow10(-scale) * float64(incCents)
incFmt := strconv.FormatFloat(incFloat, 'f', scale, 64)
dec := number.Decimal(100000.26,
    number.Scale(scale), number.IncrementString(incFmt))
p.Printf(&quot;%24v %v, %4s-rounding: %3v%v\n&quot;,
    n.Name(lang), cur, incFmt, currency.Symbol(cur), dec)</code>

By utilizing these approaches, it becomes possible to format currency values in Go using golang.org/x/text/currency while ensuring correct localization and formatting based on system locale resources or ISO currency codes.

The above is the detailed content of How to Fix Currency Formatting Issues in Go Using golang.org/x/text/currency. For more information, please follow other related articles on the PHP Chinese website!