json&cue: integrate ParsingDuration

Integrate the new jsontypes.ParsingDuration type into the cue and json
decoders via the `SingleTypeSubstitutionMangler`.

decoders/cue/cue.go

@@ -4,18 +4,32 @@ import (
 	"fmt"
 	"io"
 	"reflect"
+	"time"
 
 	"cuelang.org/go/cue/cuecontext"
 
 	"github.com/vimeo/dials"
 	"github.com/vimeo/dials/common"
+	"github.com/vimeo/dials/decoders/json/jsontypes"
 	"github.com/vimeo/dials/tagformat"
 	"github.com/vimeo/dials/transform"
 )
 
 // Decoder is a decoder that knows how to work with configs written in Cue
 type Decoder struct{}
 
+func must[T any](v T, err error) T {
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+// pre-declare the time.Duration -> jsontypes.ParsingDuration mangler at
+// package-scope, so we don't have to construct a new one every time Decode is
+// called.
+var parsingDurMangler = must(transform.NewSingleTypeSubstitutionMangler[time.Duration, jsontypes.ParsingDuration]())
+
 // Decode is a decoder that decodes the Cue config from an io.Reader into the
 // appropriate struct.
 func (d *Decoder) Decode(r io.Reader, t *dials.Type) (reflect.Value, error) {
@@ -27,7 +41,9 @@ func (d *Decoder) Decode(r io.Reader, t *dials.Type) (reflect.Value, error) {
 	const jsonTagName = "json"
 
 	// If there aren't any json tags, copy over from any dials tags.
+	// Also, convert any time.Duration fields to jsontypes.ParsingDuration so we can decode those values as strings.
 	tfmr := transform.NewTransformer(t.Type(),
+		parsingDurMangler,
 		&tagformat.TagCopyingMangler{
 			SrcTag: common.DialsTagName, NewTag: jsonTagName})
 	reflVal, tfmErr := tfmr.Translate()
@@ -43,5 +59,11 @@ func (d *Decoder) Decode(r io.Reader, t *dials.Type) (reflect.Value, error) {
 	if decErr := val.Decode(reflVal.Addr().Interface()); decErr != nil {
 		return reflect.Value{}, fmt.Errorf("failed to decode cue value into dials struct: %w", decErr)
 	}
-	return reflVal, nil
+
+	unmangledVal, unmangleErr := tfmr.ReverseTranslate(reflVal)
+	if unmangleErr != nil {
+		return reflect.Value{}, unmangleErr
+	}
+
+	return unmangledVal, nil
 }

decoders/cue/cue_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"net"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -82,8 +83,9 @@ func TestDeeplyNestedCueJSON(t *testing.T) {
 			Username   string `dials:"username"`
 			Password   string `dials:"password"`
 			OtherStuff struct {
-				Something string `dials:"something"`
-				IPAddress net.IP `dials:"ip_address"`
+				Something   string        `dials:"something"`
+				IPAddress   net.IP        `dials:"ip_address"`
+				SomeTimeout time.Duration `dials:"some_timeout"`
 			} `dials:"other_stuff"`
 		} `dials:"database_user"`
 	}
@@ -97,6 +99,7 @@ func TestDeeplyNestedCueJSON(t *testing.T) {
 			"other_stuff": {
 				"something": "asdf",
 				"ip_address": "123.10.11.121"
+				"some_timeout": "13s"
 			}
 		}
 	}`
@@ -115,6 +118,7 @@ func TestDeeplyNestedCueJSON(t *testing.T) {
 	assert.Equal(t, "test", c.DatabaseUser.Username)
 	assert.Equal(t, "password", c.DatabaseUser.Password)
 	assert.Equal(t, "asdf", c.DatabaseUser.OtherStuff.Something)
+	assert.Equal(t, time.Second*13, c.DatabaseUser.OtherStuff.SomeTimeout)
 	assert.Equal(t, net.IPv4(123, 10, 11, 121), c.DatabaseUser.OtherStuff.IPAddress)
 
 }

decoders/json/json.go

@@ -5,9 +5,11 @@ import (
 	"fmt"
 	"io"
 	"reflect"
+	"time"
 
 	"github.com/vimeo/dials"
 	"github.com/vimeo/dials/common"
+	"github.com/vimeo/dials/decoders/json/jsontypes"
 	"github.com/vimeo/dials/tagformat"
 	"github.com/vimeo/dials/transform"
 )
@@ -18,6 +20,18 @@ const JSONTagName = "json"
 // Decoder is a decoder that knows how to work with text encoded in JSON
 type Decoder struct{}
 
+func must[T any](v T, err error) T {
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+// pre-declare the time.Duration -> jsontypes.ParsingDuration mangler at
+// package-scope, so we don't have to construct a new one every time Decode is
+// called.
+var parsingDurMangler = must(transform.NewSingleTypeSubstitutionMangler[time.Duration, jsontypes.ParsingDuration]())
+
 // Decode is a decoder that decodes the JSON from an io.Reader into the
 // appropriate struct.
 func (d *Decoder) Decode(r io.Reader, t *dials.Type) (reflect.Value, error) {
@@ -28,6 +42,7 @@ func (d *Decoder) Decode(r io.Reader, t *dials.Type) (reflect.Value, error) {
 
 	// If there aren't any json tags, copy over from any dials tags.
 	tfmr := transform.NewTransformer(t.Type(),
+		parsingDurMangler,
 		&tagformat.TagCopyingMangler{
 			SrcTag: common.DialsTagName, NewTag: JSONTagName})
 	val, tfmErr := tfmr.Translate()

decoders/json/json_test.go

@@ -4,9 +4,11 @@ import (
 	"context"
 	"net"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
 	"github.com/vimeo/dials"
 	"github.com/vimeo/dials/sources/static"
 )
@@ -81,8 +83,9 @@ func TestDeeplyNestedJSON(t *testing.T) {
 			Username   string `dials:"username"`
 			Password   string `dials:"password"`
 			OtherStuff struct {
-				Something string `dials:"something"`
-				IPAddress net.IP `dials:"ip_address"`
+				Something   string        `dials:"something"`
+				IPAddress   net.IP        `dials:"ip_address"`
+				SomeTimeout time.Duration `dials:"some_timeout"`
 			} `dials:"other_stuff"`
 		} `dials:"database_user"`
 	}
@@ -95,7 +98,8 @@ func TestDeeplyNestedJSON(t *testing.T) {
 			"password": "password",
 			"other_stuff": {
 				"something": "asdf",
-				"ip_address": "123.10.11.121"
+				"ip_address": "123.10.11.121",
+				"some_timeout": "13s"
 			}
 		}
 	}`
@@ -114,6 +118,7 @@ func TestDeeplyNestedJSON(t *testing.T) {
 	assert.Equal(t, "test", c.DatabaseUser.Username)
 	assert.Equal(t, "password", c.DatabaseUser.Password)
 	assert.Equal(t, "asdf", c.DatabaseUser.OtherStuff.Something)
+	assert.Equal(t, time.Second*13, c.DatabaseUser.OtherStuff.SomeTimeout)
 	assert.Equal(t, net.IPv4(123, 10, 11, 121), c.DatabaseUser.OtherStuff.IPAddress)
 
 }