Formatting num Amounts and currency details

README.md

@@ -50,6 +50,7 @@ GOBL makes it easy to create business documents, like invoices, but checkout som
 - [GOBL for Ruby](https://github.com/invopop/gobl.ruby) - Easily build or read GOBL documents in Ruby.
 
 Conversion to local formats
+
 - [GOBL to FacturaE (Spain)](https://github.com/invopop/gobl.facturae) - convert into the [Spanish FacturaE](https://www.facturae.gob.es/Paginas/Index.aspx) format.
 - [GOBL to CFDI (Mexico)](https://github.com/invopop/gobl.cfdi) - convert into the Mexican CFDI format.
 - [GOBL to FatturaPA (Italy)](https://github.com/invopop/gobl.fatturapa) - convert into the [Italian FatturaPA](https://www.fatturapa.gov.it/it/index.html) format.
@@ -139,3 +140,11 @@ if err := env.Insert(inv); err != nil {
 	panic(err)
 }
 ```
+
+## Development
+
+GOBL uses the `go generate` command to automatically generate JSON schemas, definitions, and some Go code output. After any changes, be sure to run:
+
+```bash
+go generate .
+```

currency/README.md

@@ -1,8 +1,7 @@
 # Currency Reference Data
 
-Data sourced from ISO website and providers.
+Currency support in GOBL aims to cover most of the currencies in the world and provide methods to format and work with them.
 
-## ISO 4217
-
-Currency code data sourced from: https://www.iso.org/iso-4217-currency-codes.html
+Much of the inspiration for this package and source data in the `/data/currency` directory originally came from the excellent and widely used [money gem in ruby](https://rubymoney.github.io/money/). A few alterations to source data have been made.
 
+Currencies around the world change more often than expected, please [send a PR](https://github.com/invopop/gobl/pulls) if you spot anything that is out of date, along with a link that references the source of the change.

currency/code.go

@@ -1,9 +1,9 @@
 package currency
 
 import (
-	"github.com/invopop/gobl/num"
+	"fmt"
+
 	"github.com/invopop/jsonschema"
-	"github.com/invopop/validation"
 )
 
 // Code is the ISO currency code
@@ -12,72 +12,38 @@ type Code string
 // CodeEmpty is used when there is no code.
 const CodeEmpty Code = ""
 
-// Def provides a structure for the currencies
-type Def struct {
-	Code  Code   `json:"code"`  // three-letter currency code
-	Name  string `json:"name"`  // name of the currency
-	Num   string `json:"num"`   // three-digit currency code
-	Units uint32 `json:"units"` // how many cents are used for the currency
-}
-
-func validCodes() []interface{} {
-	list := make([]interface{}, len(CodeDefinitions))
-	for i, d := range CodeDefinitions {
-		list[i] = string(d.Code)
-	}
-	return list
-}
-
-var isValidCode = validation.In(validCodes()...)
-
 // Validate ensures the currency code is valid according
 // to the ISO 4217 three-letter list.
 func (c Code) Validate() error {
-	return validation.Validate(string(c), isValidCode)
+	return inDefinitions(c)
 }
 
-// Def provides the currency definition for the code.
-func (c Code) Def() Def {
-	d, _ := Get(c)
-	return d
-}
-
-// Get provides the code's currency definition, or
-// false if none is found.
-func Get(c Code) (Def, bool) {
-	for _, d := range CodeDefinitions {
-		if d.Code == c {
-			return d, true
-		}
+func inDefinitions(code Code) error {
+	if code == CodeEmpty {
+		return nil
 	}
-	return Def{}, false
-}
-
-// Zero provides the currency's zero amount which is pre-set with the
-// minimum precision for the currency.
-func (d Def) Zero() num.Amount {
-	return num.MakeAmount(0, d.Units)
+	if d := Get(code); d == nil {
+		return fmt.Errorf("currency code %s not defined", code)
+	}
+	return nil
 }
 
-// BaseAmount provides a definition's zero amount with the correct decimal
-// places so that it can be used as a base for calculating totals.
-//
-// Deprecated: please now use the Zero method instead.
-func (d Def) BaseAmount() num.Amount {
-	return num.MakeAmount(0, d.Units)
+// Def provides the currency definition for the code.
+func (c Code) Def() *Def {
+	return Get(c)
 }
 
 // JSONSchema provides a representation of the struct for usage in Schema.
 func (Code) JSONSchema() *jsonschema.Schema {
 	s := &jsonschema.Schema{
 		Title:       "Currency Code",
 		Type:        "string",
-		OneOf:       make([]*jsonschema.Schema, len(CodeDefinitions)),
-		Description: "ISO Currency Code",
+		OneOf:       make([]*jsonschema.Schema, len(Definitions())),
+		Description: "Currency Code as defined in the GOBL source which is expected to be ISO or commonly used alternative.",
 	}
-	for i, v := range CodeDefinitions {
+	for i, v := range Definitions() {
 		s.OneOf[i] = &jsonschema.Schema{
-			Const: v.Code,
+			Const: v.ISOCode,
 			Title: v.Name,
 		}
 	}

currency/code_test.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/invopop/gobl/currency"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestCode(t *testing.T) {
@@ -13,4 +14,12 @@ func TestCode(t *testing.T) {
 
 	d := c.Def()
 	assert.Equal(t, d.Name, "Euro")
+
+	c = currency.CodeEmpty
+	assert.NoError(t, c.Validate())
+
+	c = currency.Code("FOOO")
+	err := c.Validate()
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "currency code FOOO not defined")
 }