Annotated optional fields with omitempty by using new optional config value

docs/CHANGELOG.md

@@ -25,6 +25,7 @@ When releasing a new version:
 ### New features:
 
 - The new `optional: generic` allows using a generic type to represent optionality. See the [documentation](genqlient.yaml) for details.
+- The new `optional: pointer_omitempty` allows using a pointer that is also annotated with `omitempty`. See the [documentation](genqlient.yaml) for details.
 - For schemas with enum values that differ only in casing, it's now possible to disable smart-casing in genqlient.yaml; see the [documentation](genqlient.yaml) for `casing` for details.
 
 ### Bug fixes:

docs/genqlient.yaml

@@ -108,6 +108,9 @@ use_extensions: boolean
 #   pointers-to-slices, so the GraphQL type `[String]` will map to the Go
 #   type `[]*string`, not `*[]*string`; GraphQL null and empty list simply
 #   map to Go nil- and empty-slice.
+# - pointer_omitempty: optional fields are generated as pointers, as described above.
+#   Additionally, the fields are annotated with omitempty. Fields that are not defined,
+#   will not be exposed.
 # - generic: optional fields are generated as type parameters to a generic type
 #   specified by `optional_generic_type`. E.g. fields with GraphQL type `String`
 #   will map to the Go type `generic.Type[string]`. This is useful if you have a

generate/config.go

@@ -157,8 +157,8 @@ func (c *Config) ValidateAndFillDefaults(baseDir string) error {
 		c.ContextType = "context.Context"
 	}
 
-	if c.Optional != "" && c.Optional != "value" && c.Optional != "pointer" && c.Optional != "generic" {
-		return errorf(nil, "optional must be one of: 'value' (default), 'pointer', or 'generic'")
+	if c.Optional != "" && c.Optional != "value" && c.Optional != "pointer" && c.Optional != "pointer_omitempty" && c.Optional != "generic" {
+		return errorf(nil, "optional must be one of: 'value' (default), 'pointer', 'pointer_omitempty' or 'generic'")
 	}
 
 	if c.Optional == "generic" && c.OptionalGenericType == "" {

generate/convert.go

@@ -262,6 +262,13 @@ func (g *generator) convertType(
 		// options work, recursing here isn't as connvenient.)
 		// Note this does []*T or [][]*T, not e.g. *[][]T.  See #16.
 		goTyp = &goPointerType{goTyp}
+	} else if !options.PointerIsFalse() && (options.GetPointer() || (!typ.NonNull && g.Config.Optional == "pointer_omitempty")) {
+		goTyp = &goPointerType{Elem: goTyp}
+
+		if options.Omitempty == nil {
+			oe := true
+			options.Omitempty = &oe
+		}
 	} else if !typ.NonNull && g.Config.Optional == "generic" {
 		var genericRef string
 		genericRef, err = g.ref(g.Config.OptionalGenericType)

generate/generate_test.go

@@ -9,8 +9,9 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/Khan/genqlient/internal/testutil"
 	"gopkg.in/yaml.v2"
+
+	"github.com/Khan/genqlient/internal/testutil"
 )
 
 const (
@@ -240,6 +241,26 @@ func TestGenerateWithConfig(t *testing.T) {
 				Enums: map[string]CasingAlgorithm{"Role": CasingRaw},
 			},
 		}},
+		{"OptionalPointerOmitEmpty", "", []string{
+			"InputObject.graphql",
+			"Pointers.graphql",
+			"Omitempty.graphql",
+			"ListInput.graphql",
+		}, &Config{
+			Optional: "pointer_omitempty",
+			Bindings: map[string]*TypeBinding{
+				"Date": {
+					Type:        "time.Time",
+					Marshaler:   "github.com/Khan/genqlient/internal/testutil.MarshalDate",
+					Unmarshaler: "github.com/Khan/genqlient/internal/testutil.UnmarshalDate",
+				},
+				"DateTime": {
+					Type:        "time.Time",
+					Marshaler:   "github.com/Khan/genqlient/internal/testutil.MarshalDate",
+					Unmarshaler: "github.com/Khan/genqlient/internal/testutil.UnmarshalDate",
+				},
+			},
+		}},
 	}
 
 	sourceFilename := "SimpleQuery.graphql"