update code generation for pointer-to-pointer updating

fixes 99designs#1587

codegen/config/binder.go

@@ -212,6 +212,16 @@ func (t *TypeReference) IsPtr() bool {
 	return isPtr
 }
 
+// fix for https://github.com/golang/go/issues/31103 may make it possible to remove this (may still be useful)
+//
+func (t *TypeReference) IsPtrToPtr() bool {
+	if p, isPtr := t.GO.(*types.Pointer); isPtr {
+		_, isPtr := p.Elem().(*types.Pointer)
+		return isPtr
+	}
+	return false
+}
+
 func (t *TypeReference) IsNilable() bool {
 	return IsNilable(t.GO)
 }

codegen/type.go

@@ -26,7 +26,7 @@ func processType(ret map[string]*config.TypeReference, ref *config.TypeReference
 	}
 	ret[key] = ref
 
-	if ref.IsSlice() || ref.IsPtrToSlice() {
+	if ref.IsSlice() || ref.IsPtrToSlice() || ref.IsPtrToPtr() {
 		processType(ret, ref.Elem())
 	}
 }

codegen/type.gotpl

@@ -1,7 +1,7 @@
 {{- range $type := .ReferencedTypes }}
 	{{ with $type.UnmarshalFunc }}
 		func (ec *executionContext) {{ . }}(ctx context.Context, v interface{}) ({{ $type.GO | ref }}, error) {
-			{{- if and $type.IsNilable (not $type.GQL.NonNull) }}
+			{{- if and $type.IsNilable (not $type.GQL.NonNull) (not $type.IsPtrToPtr) }}
 				if v == nil { return nil, nil }
 			{{- end }}
 			{{- if $type.IsPtrToSlice }}
@@ -26,6 +26,16 @@
 					}
 				}
 				return res, nil
+			{{- else if and $type.IsPtrToPtr (not $type.Unmarshaler) (not $type.IsMarshaler) }}
+				var pres {{ $type.Elem.GO | ref }}
+				if v != nil {
+					res, err := ec.{{ $type.Elem.UnmarshalFunc }}(ctx, v)
+					if err != nil {
+						return nil, graphql.ErrorOnPath(ctx, err)
+					}
+					pres = res
+				}
+				return &pres, nil
 			{{- else }}
 				{{- if $type.Unmarshaler }}
 					{{- if $type.CastType }}
@@ -123,6 +133,11 @@
 					}
 				{{ end }}
 				return ret
+			{{- else if and $type.IsPtrToPtr (not $type.Unmarshaler) (not $type.IsMarshaler) }}
+				if v == nil {
+					return graphql.Null
+				}
+				return ec.{{ $type.Elem.MarshalFunc }}(ctx, sel, *v)
 			{{- else }}
 				{{- if $type.IsNilable }}
 					if v == nil {