From 6f0e5fdf0dba155ad404d9a47c179de2c2699b1e Mon Sep 17 00:00:00 2001
From: Ben Kraft <benkraft@khanacademy.org>
Date: Wed, 15 Jul 2020 12:32:21 -0700
Subject: [PATCH] unions are easy too, sorta

---
 README.md                                         |  1 -
 generate/testdata/InterfaceNoFragments.graphql.go | 14 ++++++--------
 generate/testdata/UnionNoFragments.graphql        |  5 +++++
 generate/testdata/UnionNoFragments.graphql.go     |  5 +++++
 generate/testdata/schema.graphql                  |  3 +++
 generate/types.go                                 |  7 +++----
 6 files changed, 22 insertions(+), 13 deletions(-)
 create mode 100644 generate/testdata/UnionNoFragments.graphql
 create mode 100644 generate/testdata/UnionNoFragments.graphql.go

diff --git a/README.md b/README.md
index ea4bb94..a197aa2 100644
--- a/README.md
+++ b/README.md
@@ -60,7 +60,6 @@ TODO(benkraft): Figure out how to get GitHub Actions to run the example -- it ne
 ## Major TODOs
 
 Query structures to support:
-- unions
 - fragments
 
 Config options:
diff --git a/generate/testdata/InterfaceNoFragments.graphql.go b/generate/testdata/InterfaceNoFragments.graphql.go
index 8cc38b1..cf9dc73 100644
--- a/generate/testdata/InterfaceNoFragments.graphql.go
+++ b/generate/testdata/InterfaceNoFragments.graphql.go
@@ -1,12 +1,10 @@
 type Response struct {
 	Root struct {
-		Id       string    `json:"id"`
-		Name     string    `json:"name"`
-		Children []content `json:"children"`
+		Id       string `json:"id"`
+		Name     string `json:"name"`
+		Children []struct {
+			Id   string `json:"id"`
+			Name string `json:"name"`
+		} `json:"children"`
 	} `json:"root"`
-}
-
-type content struct {
-	Id   string `json:"id"`
-	Name string `json:"name"`
 }
\ No newline at end of file
diff --git a/generate/testdata/UnionNoFragments.graphql b/generate/testdata/UnionNoFragments.graphql
new file mode 100644
index 0000000..0f4336b
--- /dev/null
+++ b/generate/testdata/UnionNoFragments.graphql
@@ -0,0 +1,5 @@
+{
+  randomLeaf {
+    __typename
+  }
+}
diff --git a/generate/testdata/UnionNoFragments.graphql.go b/generate/testdata/UnionNoFragments.graphql.go
new file mode 100644
index 0000000..d737f74
--- /dev/null
+++ b/generate/testdata/UnionNoFragments.graphql.go
@@ -0,0 +1,5 @@
+type Response struct {
+	RandomLeaf struct {
+		Typename *string `json:"__typename"`
+	} `json:"randomLeaf"`
+}
\ No newline at end of file
diff --git a/generate/testdata/schema.graphql b/generate/testdata/schema.graphql
index 6f6a136..a3b1e9f 100644
--- a/generate/testdata/schema.graphql
+++ b/generate/testdata/schema.graphql
@@ -32,6 +32,8 @@ interface Content {
   parent: Topic
 }
 
+union LeafContent = Article | Video
+
 type Article implements Content {
   id: ID!
   name: String!
@@ -56,4 +58,5 @@ type Topic implements Content {
 type Query {
   user(query: UserQueryInput): User
   root: Topic!
+  randomLeaf: LeafContent!
 }
diff --git a/generate/types.go b/generate/types.go
index d84d076..3923892 100644
--- a/generate/types.go
+++ b/generate/types.go
@@ -200,9 +200,8 @@ func (builder *typeBuilder) writeType(typ *ast.Type, selectionSet []selection, i
 	}
 
 	def := builder.schema.Types[typ.Name()]
-	// TODO: set inline = false for nested types
 	switch def.Kind {
-	case ast.Scalar, ast.Enum, ast.Union, ast.Interface:
+	case ast.Scalar, ast.Enum:
 		inline = false
 	}
 
@@ -222,7 +221,7 @@ func (builder *typeBuilder) writeType(typ *ast.Type, selectionSet []selection, i
 
 func (builder *typeBuilder) writeTypedef(typedef *ast.Definition, selectionSet []selection) error {
 	switch typedef.Kind {
-	case ast.Object, ast.InputObject, ast.Interface:
+	case ast.Object, ast.InputObject, ast.Interface, ast.Union:
 		builder.WriteString("struct {\n")
 		for _, field := range selectionSet {
 			err := builder.writeField(field)
@@ -244,7 +243,7 @@ func (builder *typeBuilder) writeTypedef(typedef *ast.Definition, selectionSet [
 		}
 		builder.WriteString(")\n")
 		return nil
-	case ast.Scalar, ast.Union:
+	case ast.Scalar:
 		// TODO(benkraft): Handle custom scalars, unions, and interfaces.
 		return fmt.Errorf("not implemented: %v", typedef.Kind)
 	default: