Allow underscore only fields and naming collisions to be aliased explicitly

codegen/config/config_test.go

@@ -87,7 +87,7 @@ func TestConfigCheck(t *testing.T) {
 		err = config.normalize()
 		require.NoError(t, err)
 
-		err = config.check()
+		err = config.Check()
 		require.EqualError(t, err, "filenames exec.go and models.go are in the same directory but have different package definitions")
 	})
 }

codegen/field.go

@@ -98,10 +98,10 @@ func (b *builder) bindField(obj *Object, f *Field) error {
 	case obj.Type == config.MapType:
 		return nil
 	case b.Config.Models[obj.Name].Fields[f.Name].FieldName != "":
-		f.Name = b.Config.Models[obj.Name].Fields[f.Name].FieldName
+		f.GoFieldName = b.Config.Models[obj.Name].Fields[f.Name].FieldName
 	}
 
-	target, err := b.findBindTarget(obj.Type.(*types.Named), f.Name)
+	target, err := b.findBindTarget(obj.Type.(*types.Named), f.GoFieldName)
 	if err != nil {
 		return err
 	}

codegen/generated!.gotpl

@@ -48,7 +48,7 @@ type ComplexityRoot struct {
 		{{ $object.Name|toCamel }} struct {
 		{{ range $field := $object.Fields -}}
 			{{ if not $field.IsReserved -}}
-				{{ $field.Name|toCamel }} {{ $field.ComplexitySignature }}
+				{{ $field.GoFieldName }} {{ $field.ComplexitySignature }}
 			{{ end }}
 		{{- end }}
 		}
@@ -86,8 +86,8 @@ func (e *executableSchema) Complexity(typeName, field string, childComplexity in
 		{{ if not $object.IsReserved }}
 			{{ range $field := $object.Fields }}
 				{{ if not $field.IsReserved }}
-					case "{{$object.Name}}.{{$field.Name}}":
-						if e.complexity.{{$object.Name|toCamel}}.{{$field.Name|toCamel}} == nil {
+					case "{{$object.Name}}.{{$field.GoFieldName}}":
+						if e.complexity.{{$object.Name|toCamel}}.{{$field.GoFieldName}} == nil {
 							break
 						}
 						{{ if $field.Args }}
@@ -96,7 +96,7 @@ func (e *executableSchema) Complexity(typeName, field string, childComplexity in
 								return 0, false
 							}
 						{{ end }}
-						return e.complexity.{{$object.Name|toCamel}}.{{$field.Name|toCamel}}(childComplexity{{if $field.Args}}, {{$field.ComplexityArgs}} {{end}}), true
+						return e.complexity.{{$object.Name|toCamel}}.{{$field.GoFieldName}}(childComplexity{{if $field.Args}}, {{$field.ComplexityArgs}} {{end}}), true
 				{{ end }}
 			{{ end }}
 		{{ end }}

codegen/templates/templates.go

@@ -229,6 +229,9 @@ func Call(p *types.Func) string {
 }
 
 func ToCamel(s string) string {
+	if s == "_" {
+		return "_"
+	}
 	buffer := make([]rune, 0, len(s))
 	upper := true
 	lastWasUpper := false
@@ -288,6 +291,7 @@ var keywords = []string{
 	"import",
 	"return",
 	"var",
+	"_",
 }
 
 // sanitizeKeywords prevents collisions with go keywords for arguments to resolver functions