func (v *{{.Type}}) UnmarshalJSON(b []byte) error {
	var firstPass struct{
		*{{.Type}}
        {{range .Fields -}}
		{{.GoName}} json.RawMessage `json:"{{.JSONName}}"`
        {{end}}
	}
	firstPass.{{.Type}} = v

	err := json.Unmarshal(b, &typenames)
    if err != nil {
        return err
    }

    {{range .Fields -}}
	var tn struct { TypeName string `json:"__typename"` }
	err = json.Unmarshal(firstPass.{{.GoName}}, &tn)
    if err != nil {
        return err
    }
	switch tn.TypeName {
    {{with $field := .}}
    {{range $field.ConcreteTypes}}
	case "{{.GraphQLName}}":
		v.{{$field.GoName}} = {{.GoName}}{}
		err = json.Unmarshal(
			firstPass.{{$field.GoName}}, &v.{{$field.GoName}})
    {{end}}
    {{end}}
	}
    if err != nil {
        return err
    }
    {{end}}
}