add omitempty

generate/testdata/queries/Omitempty.graphql

@@ -0,0 +1,11 @@
+# @genqlient(omitempty: true)
+query OmitEmptyQuery(
+  $query: UserQueryInput,
+  $dt: DateTime,
+  $tz: String,
+) {
+  user(query: $query) {
+    id
+  }
+  maybeConvert(dt: $dt, tz: $tz)
+}

generate/testdata/queries/Omitempty.graphql.go

@@ -0,0 +1,79 @@
+package test
+
+// Code generated by github.com/Khan/genqlient, DO NOT EDIT.
+
+import (
+	"time"
+
+	"github.com/Khan/genqlient/graphql"
+	"github.com/me/mypkg"
+)
+
+type OmitEmptyQueryResponse struct {
+	User         OmitEmptyQueryUser `json:"user"`
+	MaybeConvert time.Time          `json:"maybeConvert"`
+}
+
+type OmitEmptyQueryUser struct {
+	Id mypkg.ID `json:"id"`
+}
+
+type Role string
+
+const (
+	RoleStudent Role = "STUDENT"
+	RoleTeacher Role = "TEACHER"
+)
+
+type UserQueryInput struct {
+	Email string   `json:"email"`
+	Name  string   `json:"name"`
+	Id    mypkg.ID `json:"id"`
+	Role  Role     `json:"role"`
+	Names []string `json:"names"`
+}
+
+func OmitEmptyQuery(
+	client graphql.Client,
+	query UserQueryInput,
+	dt time.Time,
+	tz string,
+) (*OmitEmptyQueryResponse, error) {
+	variables := map[string]interface{}{
+		"query": nil,
+		"dt":    nil,
+		"tz":    nil,
+	}
+
+	var zero_query UserQueryInput
+	if query != zero_query {
+		variables["query"] = query
+	}
+
+	var zero_dt time.Time
+	if dt != zero_dt {
+		variables["dt"] = dt
+	}
+
+	var zero_tz string
+	if tz != zero_tz {
+		variables["tz"] = tz
+	}
+
+	var retval OmitEmptyQueryResponse
+	err := client.MakeRequest(
+		nil,
+		"OmitEmptyQuery",
+		`
+query OmitEmptyQuery ($query: UserQueryInput, $dt: DateTime, $tz: String) {
+	user(query: $query) {
+		id
+	}
+	maybeConvert(dt: $dt, tz: $tz)
+}
+`,
+		&retval,
+		variables,
+	)
+	return &retval, err
+}

generate/testdata/queries/Omitempty.graphql.json

@@ -0,0 +1,9 @@
+{
+  "operations": [
+    {
+      "operationName": "OmitEmptyQuery",
+      "query": "\nquery OmitEmptyQuery ($query: UserQueryInput, $dt: DateTime, $tz: String) {\n\tuser(query: $query) {\n\t\tid\n\t}\n\tmaybeConvert(dt: $dt, tz: $tz)\n}\n",
+      "sourceLocation": "testdata/queries/Omitempty.graphql"
+    }
+  ]
+}

generate/testdata/queries/schema.graphql

@@ -63,6 +63,7 @@ type Query {
   root: Topic!
   randomLeaf: LeafContent!
   convert(dt: DateTime!, tz: String): DateTime!
+  maybeConvert(dt: DateTime, tz: String): DateTime
 }
 
 type Mutation {