fix missing return in model plugin getObject;

refactor to use `getObject` to create the base struct to be used in embedding;
add test for embedded structs;
update models.gotpl to not create the `` for tags when there are no tags

Author: Adrian Lungu

plugin/modelgen/models.go

@@ -117,6 +117,19 @@ func (m *Plugin) MutateConfig(cfg *config.Config) error {
 				return err
 			}
 
+			if !cfg.OmitEmbeddedStructs {
+				ob, err := m.getObject(cfg, schemaType, b)
+				if err != nil {
+					return err
+				}
+				if ob == nil {
+					continue
+				}
+
+				ob.Name = fmt.Sprintf("%s%s", cfg.EmbeddedStructsPrefix, ob.Name)
+				b.Models = append(b.Models, ob)
+			}
+
 			b.Interfaces = append(b.Interfaces, it)
 		}
 	}
@@ -131,6 +144,9 @@ func (m *Plugin) MutateConfig(cfg *config.Config) error {
 			if err != nil {
 				return err
 			}
+			if it == nil {
+				continue
+			}
 
 			b.Models = append(b.Models, it)
 		case ast.Enum:
@@ -739,17 +755,6 @@ func (m *Plugin) getInterface(cfg *config.Config, schemaType *ast.Definition, b
 		}
 	}
 
-	if !cfg.OmitEmbeddedStructs {
-		it := &Object{
-			Description: schemaType.Description,
-			// To not conflict with the interface name, we prefix the struct name with "Base"
-			Name:   fmt.Sprintf("%s%s", cfg.EmbeddedStructsPrefix, schemaType.Name),
-			Fields: fields,
-		}
-
-		b.Models = append(b.Models, it)
-	}
-
 	it := &Interface{
 		Description: schemaType.Description,
 		Name:        schemaType.Name,
@@ -774,6 +779,8 @@ func (m *Plugin) getObject(cfg *config.Config, schemaType *ast.Definition, b *Mo
 				Name:        schemaType.Name,
 			}, nil
 		}
+
+		return nil, nil
 	}
 
 	fields, err := m.generateFields(cfg, schemaType, b)

plugin/modelgen/models.gotpl

@@ -37,7 +37,7 @@
 			{{- with .Description }}
 				{{.|prefixLines "// "}}
 			{{- end}}
-			{{ $field.GoName }} {{$field.Type | ref}} `{{$field.Tag}}`
+			{{ $field.GoName }} {{$field.Type | ref}} {{if $field.Tag}}`{{end}}{{$field.Tag}}{{if $field.Tag}}`{{end}}
 		{{- end }}
 	}
 

plugin/modelgen/models_test.go

@@ -315,6 +315,32 @@ func TestModelGenerationOmitRootModels(t *testing.T) {
 	require.NotContains(t, string(generated), "type Subscription struct")
 }
 
+func TestModelGenerationDontOmitEmbeddedStructs(t *testing.T) {
+	cfg, err := config.LoadConfig("testdata/gqlgen_embedded_structs_models.yml")
+	require.NoError(t, err)
+	require.NoError(t, cfg.Init())
+	p := Plugin{
+		FieldHook: DefaultFieldMutateHook,
+	}
+	require.NoError(t, p.MutateConfig(cfg))
+	require.NoError(t, goBuild(t, "./out_embedded_structs_models/"))
+	generated, err := os.ReadFile("./out_embedded_structs_models/generated_embedded_structs_models.go")
+	require.NoError(t, err)
+	require.Contains(t, string(generated), "type BaseElement")
+
+	carbonStr := getStringInBetween(string(generated), "type Carbon struct {", "}")
+	require.NotEqual(t, carbonStr, "")
+	require.Contains(t, carbonStr, "BaseElement")
+
+	magnesiumStr := getStringInBetween(string(generated), "type Magnesium struct {", "}")
+	require.NotEqual(t, magnesiumStr, "")
+	require.Contains(t, magnesiumStr, "BaseElement")
+
+	potassiumStr := getStringInBetween(string(generated), "type Potassium struct {", "}")
+	require.NotEqual(t, potassiumStr, "")
+	require.Contains(t, potassiumStr, "BaseElement")
+}
+
 func TestModelGenerationOmitResolverFields(t *testing.T) {
 	cfg, err := config.LoadConfig("testdata/gqlgen_omit_resolver_fields.yml")
 	require.NoError(t, err)
@@ -699,3 +725,18 @@ func TestCustomTemplate(t *testing.T) {
 	}
 	require.NoError(t, p.MutateConfig(cfg))
 }
+
+func getStringInBetween(str string, start string, end string) string {
+	startIndex := strings.Index(str, start)
+	if startIndex == -1 {
+		return ""
+	}
+
+	newStr := str[startIndex+len(start):]
+	e := strings.Index(newStr, end)
+	if e == -1 {
+		return ""
+	}
+
+	return newStr[:e]
+}

plugin/modelgen/out_embedded_structs_models/generated_embedded_structs_models.go

@@ -0,0 +1,7 @@
+schema:
+  - "testdata/schema_embedded_structs_models.graphql"
+
+model:
+  filename: out_embedded_structs_models/generated_embedded_structs_models.go
+
+omit_embedded_structs: false

plugin/modelgen/testdata/gqlgen_embedded_structs_models.yml

@@ -0,0 +1,26 @@
+interface Node {
+    id: ID!
+}
+
+interface Element implements Node {
+    id: ID!
+    name: String!
+}
+
+type Magnesium implements Element & Node {
+    id: ID!
+    name: String!
+    types: Int!
+}
+
+type Potassium implements Element & Node {
+    id: ID!
+    name: String!
+    price: Float!
+}
+
+type Carbon implements Element & Node {
+    id: ID!
+    name: String!
+    footprint: String!
+}