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我有这些实体：

  • Golang结构：
type Player struct {
    ID        int
    CreatedAt time.Time
    City      City
    CityID    int
    Team      *Team
    TeamID    *int
    Score     int
}
  • GraphQL 架构：
type Player {
  id: ID!
  createdAt: Time!
  City: City!
  Team: Team
  Score: Int!
}

如你看到的：

  1. City是强制性的

  2. Team（TeamID在 Golang 结构中）不是强制性的，所以我使用的是指针类型 ( *)

我现在不明白的是如何使用dataloaden（一个 GraphQL 数据加载器）。

这里生成的CityById加载器代码，生成go run github.com/vektah/dataloaden CityByIdLoader int *my_project/entities.City：

CityById: CityByIdLoader{
  maxBatch: 100,
  wait:     1 * time.Millisecond,
  fetch: func(keys []int) ([]*entities.City, []error) {
    cities, err := myRepo.CitiesByKeys(keys)
    // directly ordered in DB based on keys` order: it works
    return cities, []error{err}
  },
},

为什么[]*int呢TeamID？

TeamById这是加载程序的生成代码，使用以下代码生成go run github.com/vektah/dataloaden TeamByIdLoader *int *my_project/entities.Team：：

TeamById: TeamByIdLoader{
  maxBatch: 100,
  wait:     1 * time.Millisecond,
  fetch: func(keys []int) ([]*entities.Team, []error) {
    teams, err := myRepo.TeamsByKeys(keys)
    // I cannot order in DB because of `NULL` keys, right?
    // How to order these results?
    return teams, []error{err}
  },
},

如果由于NULL.keys

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