From 3bbc2a342fc7a0839b25e26ebd0aa25d7f498dac Mon Sep 17 00:00:00 2001
From: Daniel Vladco <vladcodaniel@gmail.com>
Date: Mon, 25 Oct 2021 00:17:45 +0300
Subject: [PATCH] feat: generate resolvers for inputs if fields are missing
 (#1404)

Co-authored-by: daniel vladco <daniel.vladco@siriusxm.com>
Co-authored-by: davladco@cisco.com <davladco@cisco.com>
---
 codegen/field.go         | 10 ++++++++++
 codegen/generated!.gotpl | 19 ++++++++++++++++++-
 codegen/input.gotpl      | 28 +++++++++++++++++++++++-----
 3 files changed, 51 insertions(+), 6 deletions(-)

diff --git a/codegen/field.go b/codegen/field.go
index 0833c1ebfba..245632aac02 100644
--- a/codegen/field.go
+++ b/codegen/field.go
@@ -461,6 +461,9 @@ func (f *Field) GoNameUnexported() string {
 }
 
 func (f *Field) ShortInvocation() string {
+	if f.Object.Kind == ast.InputObject {
+		return fmt.Sprintf("%s().%s(ctx, &it, data)", strings.Title(f.Object.Definition.Name), f.GoFieldName)
+	}
 	return fmt.Sprintf("%s().%s(%s)", strings.Title(f.Object.Definition.Name), f.GoFieldName, f.CallArgs())
 }
 
@@ -481,6 +484,13 @@ func (f *Field) ResolverType() string {
 }
 
 func (f *Field) ShortResolverDeclaration() string {
+	if f.Object.Kind == ast.InputObject {
+		return fmt.Sprintf("(ctx context.Context, obj %s, data %s) error",
+			templates.CurrentImports.LookupType(f.Object.Reference()),
+			templates.CurrentImports.LookupType(f.TypeReference.GO),
+		)
+	}
+
 	res := "(ctx context.Context"
 
 	if !f.Object.Root {
diff --git a/codegen/generated!.gotpl b/codegen/generated!.gotpl
index e72fdd08bca..bf59daccef9 100644
--- a/codegen/generated!.gotpl
+++ b/codegen/generated!.gotpl
@@ -36,7 +36,12 @@
 			{{ucFirst $object.Name}}() {{ucFirst $object.Name}}Resolver
 		{{ end }}
 	{{- end }}
-	}
+	{{- range $object := .Inputs -}}
+	{{ if $object.HasResolvers -}}
+		{{ucFirst $object.Name}}() {{ucFirst $object.Name}}Resolver
+	{{ end }}
+{{- end }}
+}
 
 	type DirectiveRoot struct {
 	{{ range $directive := .Directives }}
@@ -72,6 +77,18 @@
 	{{- end }}
 {{- end }}
 
+{{ range $object := .Inputs -}}
+	{{ if $object.HasResolvers }}
+		type {{$object.Name}}Resolver interface {
+		{{ range $field := $object.Fields -}}
+			{{- if $field.IsResolver }}
+				{{- $field.GoFieldName}}{{ $field.ShortResolverDeclaration }}
+			{{- end }}
+		{{ end }}
+		}
+	{{- end }}
+{{- end }}
+
 {{ if eq .Config.Exec.Layout "single-file" }}
 	type executableSchema struct {
 		resolvers  ResolverRoot
diff --git a/codegen/input.gotpl b/codegen/input.gotpl
index 64681b61da3..5694bcd613c 100644
--- a/codegen/input.gotpl
+++ b/codegen/input.gotpl
@@ -29,20 +29,38 @@
 						return it, graphql.ErrorOnPath(ctx, err)
 					}
 					if data, ok := tmp.({{ $field.TypeReference.GO | ref }}) ; ok {
-						it.{{$field.GoFieldName}} = data
+						{{- if $field.IsResolver }}
+							if err = ec.resolvers.{{ $field.ShortInvocation }}; err != nil {
+								return it, err
+							}
+						{{- else }}
+							it.{{$field.GoFieldName}} = data
+						{{- end }}
 					{{- if $field.TypeReference.IsNilable }}
+						{{- if not $field.IsResolver }}
 						} else if tmp == nil {
 							it.{{$field.GoFieldName}} = nil
+						{{- end }}
 					{{- end }}
 					} else {
 						err := fmt.Errorf(`unexpected type %T from directive, should be {{ $field.TypeReference.GO }}`, tmp)
 						return it, graphql.ErrorOnPath(ctx, err)
 					}
 				{{- else }}
-					it.{{$field.GoFieldName}}, err = ec.{{ $field.TypeReference.UnmarshalFunc }}(ctx, v)
-					if err != nil {
-						return it, err
-					}
+					{{- if $field.IsResolver }}
+						data, err := ec.{{ $field.TypeReference.UnmarshalFunc }}(ctx, v)
+						if err != nil {
+							return it, err
+						}
+						if err = ec.resolvers.{{ $field.ShortInvocation }}; err != nil {
+							return it, err
+						}
+					{{- else }}
+						it.{{$field.GoFieldName}}, err = ec.{{ $field.TypeReference.UnmarshalFunc }}(ctx, v)
+						if err != nil {
+							return it, err
+						}
+					{{- end }}
 				{{- end }}
 			{{- end }}
 			}