strings: support for parsing multiple string values (#18)

Author: shoenig

README.md

@@ -24,13 +24,19 @@ import "cattlecloud.net/go/forms"
 
 ```go
 var (
-  name string
-  age  int
+  name     string
+  age      int
+  aliases  []string
+  worth    float64
+  password *conceal.Text
 )
 
 err := forms.Parse(request, forms.Schema{
-  "NAME": forms.String(&name),
-  "AGE":  forms.Int(&age),
+  "name":     forms.String(&name),
+  "age":      forms.Int(&age),
+  "aliases":  forms.Strings(&aliases),
+  "worth":    forms.Float64(&worth),
+  "password": forms.Secret(&pword),
 })
 ```
 

forms.go

@@ -13,6 +13,7 @@ import (
 	"strconv"
 
 	"github.com/shoenig/go-conceal"
+	"github.com/shoenig/lang"
 )
 
 var (
@@ -104,6 +105,31 @@ func StringOr[T StringType](s *T, alt T) Parser {
 	}
 }
 
+type stringsParser[T StringType] struct {
+	required    bool
+	destination *[]T
+}
+
+func (p *stringsParser[T]) Parse(values []string) error {
+	switch {
+	case len(values) == 0 && p.required:
+		return ErrNoValue
+	case len(values) == 0:
+		return nil
+	default:
+		*p.destination = lang.Map(values, func(s string) T { return T(s) })
+	}
+	return nil
+}
+
+// Strings is used to extract a form data value into a slice of Go strings.
+func Strings[T StringType](s *[]T) Parser {
+	return &stringsParser[T]{
+		required:    true,
+		destination: s,
+	}
+}
+
 // Secret is used to extract a form data value into a Go conceal.Text. If the
 // value is missing then an error is returned during parsing.
 func Secret(s **conceal.Text) Parser {

forms_test.go

@@ -363,3 +363,19 @@ func Test_Parse_IntType_IntOr(t *testing.T) {
 	must.NoError(t, err)
 	must.Eq(t, 100, age)
 }
+
+func Test_Parse_StringType_Strings(t *testing.T) {
+	t.Parallel()
+
+	data := url.Values{
+		"names": []string{"alice", "bob", "carol"},
+	}
+
+	var names []string
+
+	err := ParseValues(data, Schema{
+		"names": Strings(&names),
+	})
+	must.NoError(t, err)
+	must.Eq(t, []string{"alice", "bob", "carol"}, names)
+}

go.mod

@@ -4,6 +4,7 @@ go 1.23
 
 require (
 	github.com/shoenig/go-conceal v0.5.4
+	github.com/shoenig/lang v0.0.6
 	github.com/shoenig/test v1.12.2
 )
 

go.sum

@@ -2,5 +2,7 @@ github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/shoenig/go-conceal v0.5.4 h1:xLzarDUw3vUJjz+DirzO58yijkX4I9F1KA+RPZMLGLY=
 github.com/shoenig/go-conceal v0.5.4/go.mod h1:LXmjZn/bO1Nrtvfex4VNbKViVE+aMhVvskZx8o7HBfs=
+github.com/shoenig/lang v0.0.6 h1:i8NVe+fNQLUGXk+KPP6lB6Jcfmcrmc9nCEYknHsBbVQ=
+github.com/shoenig/lang v0.0.6/go.mod h1:DStvcG5yPYr/xBBcTEaousm+Pqjn9ozAKfyqWwfhj34=
 github.com/shoenig/test v1.12.2 h1:ZVT8NeIUwGWpZcKaepPmFMoNQ3sVpxvqUh/MAqwFiJI=
 github.com/shoenig/test v1.12.2/go.mod h1:UxJ6u/x2v/TNs/LoLxBNJRV9DiwBBKYxXSyczsBHFoI=