Add encore.dev/types/option package

This adds a new `encore.dev/types/option` package for Encore.go,
with a new type option.Option[T] for representing optional values.

This improves Encore's support for representing optional types in APIs.
It's also something that we've internally found to be useful again and again
in large code bases, where it's difficult to keep track of whether a pointer value
*T means the type is nullable or not.

Author: eandre

cli/daemon/run/call.go

@@ -178,16 +178,27 @@ func handleResponse(md *v1.Data, p *ApiCallParams, headers http.Header, body []b
 	members := make([]hujson.ObjectMember, 0)
 	if rpcEncoding.ResponseEncoding != nil {
 		for i, m := range rpcEncoding.ResponseEncoding.HeaderParameters {
-			value := headers.Get(m.Name)
+			values := headers.Values(m.Name)
 
 			var beforeExtra []byte
 			if i == 0 {
 				beforeExtra = []byte("\n    // HTTP Headers\n    ")
 			}
 
+			var val hujson.Value
+			if len(values) == 1 {
+				val = hujson.Value{Value: hujson.String(values[0])}
+			} else {
+				arr := &hujson.Array{}
+				for _, v := range values {
+					arr.Elements = append(arr.Elements, hujson.Value{Value: hujson.String(v)})
+				}
+				val = hujson.Value{Value: arr}
+			}
+
 			members = append(members, hujson.ObjectMember{
 				Name:  hujson.Value{Value: hujson.String(m.Name), BeforeExtra: beforeExtra},
-				Value: hujson.Value{Value: hujson.String(value)},
+				Value: val,
 			})
 		}
 

cli/daemon/schema.go

@@ -49,6 +49,8 @@ func (r *schemaRenderer) renderType(typ *schema.Type) {
 		r.renderNamed(typ.Named)
 	case *schema.Type_Pointer:
 		r.renderType(typ.Pointer.Base)
+	case *schema.Type_Option:
+		r.WriteNil()
 	case *schema.Type_Union:
 		r.renderType(typ.Union.Types[0])
 	case *schema.Type_Literal:

docs/go/primitives/defining-apis.md

@@ -284,22 +284,29 @@ type CreateBlogPost struct {
 }
 ```
 
+### Optional types
+
+Encore supports optional types using the `option.Option[T]` type from the `encore.dev/types/option` package.
+This can be used in request and response schemas to indicate that the value is not always set.
+
+See the [package documentation](https://pkg.go.dev/encore.dev/types/option) for more information on usage.
+
 ### Supported types
 The table below lists the data types supported by each HTTP message location.
 
-| Type            | Header | Path | Query | Body |
-| --------------- | ------ | ---- | ----- | ---- |
-| bool            | X      | X    | X     | X    |
-| numeric         | X      | X    | X     | X    |
-| string          | X      | X    | X     | X    |
-| time.Time       | X      | X    | X     | X    |
-| uuid.UUID       | X      | X    | X     | X    |
-| json.RawMessage | X      | X    | X     | X    |
-| list            |        |      | X     | X    |
-| struct          |        |      |       | X    |
-| map             |        |      |       | X    |
-| pointer         |        |      |       | X    |
-
+| Type             | Header | Path | Query | Body |
+| ---------------- | ------ | ---- | ----- | ---- |
+| bool             | X      | X    | X     | X    |
+| numeric          | X      | X    | X     | X    |
+| string           | X      | X    | X     | X    |
+| time.Time        | X      | X    | X     | X    |
+| uuid.UUID        | X      | X    | X     | X    |
+| json.RawMessage  | X      | X    | X     | X    |
+| option.Option[T] | X      |      | X     | X    |
+| pointer          | X      |      | X     | X    |
+| list             | X      |      | X     | X    |
+| struct           |        |      |       | X    |
+| map              |        |      |       | X    |
 
 ## Sensitive data
 

e2e-tests/testdata/echo/endtoend/endtoend.go

@@ -5,16 +5,19 @@ import (
 	"encoding/json"
 	"fmt"
 	"math/rand"
+
 	// "net/http"
 	// "net/http/httptest"
 	"os"
 	"reflect"
+
 	// "strings"
 	"time"
 
 	"encore.app/test"
 	"encore.dev/beta/errs"
 	"encore.dev/rlog"
+	"encore.dev/types/option"
 	"encore.dev/types/uuid"
 )
 
@@ -92,35 +95,38 @@ func GeneratedWrappersEndToEndTest(ctx context.Context) (err error) {
 	r.Read(queryBytes)
 	r.Read(bodyBytes)
 	params := &test.MarshallerTest[int]{
-		HeaderBoolean: r.Float32() > 0.5,
-		HeaderInt:     r.Int(),
-		HeaderFloat:   r.Float64(),
-		HeaderString:  "header string",
-		HeaderBytes:   headerBytes,
-		HeaderTime:    time.Now().Truncate(time.Second),
-		HeaderJson:    json.RawMessage("{\"hello\":\"world\"}"),
-		HeaderUUID:    newUUID(),
-		HeaderUserID:  "432",
-		QueryBoolean:  r.Float32() > 0.5,
-		QueryInt:      r.Int(),
-		QueryFloat:    r.Float64(),
-		QueryString:   "query string",
-		QueryBytes:    headerBytes,
-		QueryTime:     time.Now().Add(time.Duration(rand.Intn(1024)) * time.Hour).Truncate(time.Second),
-		QueryJson:     json.RawMessage("true"),
-		QueryUUID:     newUUID(),
-		QueryUserID:   "9udfa",
-		QuerySlice:    []int{r.Int(), r.Int(), r.Int(), r.Int()},
-		BodyBoolean:   r.Float32() > 0.5,
-		BodyInt:       r.Int(),
-		BodyFloat:     r.Float64(),
-		BodyString:    "body string",
-		BodyBytes:     bodyBytes,
-		BodyTime:      time.Now().Add(time.Duration(rand.Intn(1024)) * time.Hour).Truncate(time.Second),
-		BodyJson:      json.RawMessage("null"),
-		BodyUUID:      newUUID(),
-		BodyUserID:    "✉️",
-		BodySlice:     []int{r.Int(), r.Int(), r.Int(), r.Int(), r.Int(), r.Int()},
+		HeaderBoolean:     r.Float32() > 0.5,
+		HeaderInt:         r.Int(),
+		HeaderFloat:       r.Float64(),
+		HeaderString:      "header string",
+		HeaderBytes:       headerBytes,
+		HeaderTime:        time.Now().Truncate(time.Second),
+		HeaderJson:        json.RawMessage("{\"hello\":\"world\"}"),
+		HeaderUUID:        newUUID(),
+		HeaderUserID:      "432",
+		HeaderOption:      option.Some("test"),
+		QueryBoolean:      r.Float32() > 0.5,
+		QueryInt:          r.Int(),
+		QueryFloat:        r.Float64(),
+		QueryString:       "query string",
+		QueryBytes:        headerBytes,
+		QueryTime:         time.Now().Add(time.Duration(rand.Intn(1024)) * time.Hour).Truncate(time.Second),
+		QueryJson:         json.RawMessage("true"),
+		QueryUUID:         newUUID(),
+		QueryUserID:       "9udfa",
+		QuerySlice:        []int{r.Int(), r.Int(), r.Int(), r.Int()},
+		QuerySliceOptions: []option.Option[int]{option.Some(r.Int()), option.None[int](), option.Some(r.Int())},
+		BodyBoolean:       r.Float32() > 0.5,
+		BodyInt:           r.Int(),
+		BodyFloat:         r.Float64(),
+		BodyString:        "body string",
+		BodyBytes:         bodyBytes,
+		BodyTime:          time.Now().Add(time.Duration(rand.Intn(1024)) * time.Hour).Truncate(time.Second),
+		BodyJson:          json.RawMessage("null"),
+		BodyUUID:          newUUID(),
+		BodyUserID:        "✉️",
+		BodySlice:         []int{r.Int(), r.Int(), r.Int(), r.Int(), r.Int(), r.Int()},
+		BodyOption:        option.Some(r.Int()),
 	}
 	mResp, err := test.MarshallerTestHandler(ctx, params)
 	assert(err, nil, "Expected no error from the marshaller test")

e2e-tests/testdata/echo/test/endpoints.go

@@ -11,6 +11,7 @@ import (
 	encore "encore.dev"
 	"encore.dev/beta/auth"
 	"encore.dev/beta/errs"
+	"encore.dev/types/option"
 	"encore.dev/types/uuid"
 )
 
@@ -98,35 +99,38 @@ func RestStyleAPI(ctx context.Context, objType int, name string, params *RestPar
 }
 
 type MarshallerTest[A any] struct {
-	HeaderBoolean bool            `header:"x-boolean"`
-	HeaderInt     int             `header:"x-int"`
-	HeaderFloat   float64         `header:"x-float"`
-	HeaderString  string          `header:"x-string"`
-	HeaderBytes   []byte          `header:"x-bytes"`
-	HeaderTime    time.Time       `header:"x-time"`
-	HeaderJson    json.RawMessage `header:"x-json"`
-	HeaderUUID    uuid.UUID       `header:"x-uuid"`
-	HeaderUserID  auth.UID        `header:"x-user-id"`
-	QueryBoolean  bool            `qs:"boolean"`
-	QueryInt      int             `qs:"int"`
-	QueryFloat    float64         `qs:"float"`
-	QueryString   string          `qs:"string"`
-	QueryBytes    []byte          `qs:"bytes"`
-	QueryTime     time.Time       `qs:"time"`
-	QueryJson     json.RawMessage `qs:"json"`
-	QueryUUID     uuid.UUID       `qs:"uuid"`
-	QueryUserID   auth.UID        `qs:"user-id"`
-	QuerySlice    []A             `qs:"slice"`
-	BodyBoolean   bool            `json:"boolean"`
-	BodyInt       int             `json:"int"`
-	BodyFloat     float64         `json:"float"`
-	BodyString    string          `json:"string"`
-	BodyBytes     []byte          `json:"bytes"`
-	BodyTime      time.Time       `json:"time"`
-	BodyJson      json.RawMessage `json:"json"`
-	BodyUUID      uuid.UUID       `json:"uuid"`
-	BodyUserID    auth.UID        `json:"user-id"`
-	BodySlice     []A             `json:"slice"`
+	HeaderBoolean     bool                  `header:"x-boolean"`
+	HeaderInt         int                   `header:"x-int"`
+	HeaderFloat       float64               `header:"x-float"`
+	HeaderString      string                `header:"x-string"`
+	HeaderBytes       []byte                `header:"x-bytes"`
+	HeaderTime        time.Time             `header:"x-time"`
+	HeaderJson        json.RawMessage       `header:"x-json"`
+	HeaderUUID        uuid.UUID             `header:"x-uuid"`
+	HeaderUserID      auth.UID              `header:"x-user-id"`
+	HeaderOption      option.Option[string] `header:"x-option"`
+	QueryBoolean      bool                  `qs:"boolean"`
+	QueryInt          int                   `qs:"int"`
+	QueryFloat        float64               `qs:"float"`
+	QueryString       string                `qs:"string"`
+	QueryBytes        []byte                `qs:"bytes"`
+	QueryTime         time.Time             `qs:"time"`
+	QueryJson         json.RawMessage       `qs:"json"`
+	QueryUUID         uuid.UUID             `qs:"uuid"`
+	QueryUserID       auth.UID              `qs:"user-id"`
+	QuerySlice        []A                   `qs:"slice"`
+	QuerySliceOptions []option.Option[A]    `qs:"slice-options"`
+	BodyBoolean       bool                  `json:"boolean"`
+	BodyInt           int                   `json:"int"`
+	BodyFloat         float64               `json:"float"`
+	BodyString        string                `json:"string"`
+	BodyBytes         []byte                `json:"bytes"`
+	BodyTime          time.Time             `json:"time"`
+	BodyJson          json.RawMessage       `json:"json"`
+	BodyUUID          uuid.UUID             `json:"uuid"`
+	BodyUserID        auth.UID              `json:"user-id"`
+	BodySlice         []A                   `json:"slice"`
+	BodyOption        option.Option[A]      `json:"option"`
 }
 
 // MarshallerTestHandler allows us to test marshalling of all the inbuilt types in all

internal/gocodegen/helpers.go

@@ -79,6 +79,9 @@ func ConvertSchemaToJenType(typ *schema.Type, md *meta.Data) *Statement {
 	case *schema.Type_Pointer:
 		return Op("*").Add(ConvertSchemaToJenType(typ.Pointer.Base, md))
 
+	case *schema.Type_Option:
+		return Qual("encore.dev/types/option", "Option").Types(ConvertSchemaToJenType(typ.Option.Value, md))
+
 	case *schema.Type_TypeParameter:
 		return Id(md.Decls[typ.TypeParameter.DeclId].TypeParams[typ.TypeParameter.ParamIdx].Name)