gqlserver2: dataloaders10

dataloaders.go

func newAgentByAuthorID(ctx context.Context, repo pg.Repository) *AgentLoader {
	return NewAgentLoader(AgentLoaderConfig{
		MaxBatch: 100,
		Wait:     5 * time.Millisecond,
		Fetch: func(authorIDs []int64) ([]*pg.Agent, []error) {
			// db query
			res, err := repo.ListAgentsByAuthorIDs(ctx, authorIDs)
			if err != nil {
				return nil, []error{err}
			}
			// map
			groupByAuthorID := make(map[int64]*pg.Agent, len(authorIDs))
			for _, r := range res {
				groupByAuthorID[r.AuthorID] = &pg.Agent{
					ID:    r.ID,
					Name:  r.Name,
					Email: r.Email,
				}
			}
			// order
			result := make([]*pg.Agent, len(authorIDs))
			for i, authorID := range authorIDs {
				result[i] = groupByAuthorID[authorID]
			}
			return result, nil
		},
	})
}