server/graph/loaders/activityloader.go

package loaders

import (
	"context"
	"git.aiterp.net/stufflog/server/database/repositories"
	"git.aiterp.net/stufflog/server/internal/slerrors"
	"git.aiterp.net/stufflog/server/models"
	"time"
)

// go run github.com/vektah/dataloaden ActivityLoader string \*git.aiterp.net/stufflog/server/models.Activity

var activityLoaderCtxKey = "ctx.stufflog.ActivityLoader"

func ActivityLoaderFromContext(ctx context.Context) *ActivityLoader {
	return ctx.Value(activityLoaderCtxKey).(*ActivityLoader)
}

func NewActivityLoader(ctx context.Context, activityRepo repositories.ActivityRepository) *ActivityLoader {
	return &ActivityLoader{
		fetch: func(keys []string) ([]*models.Activity, []error) {
			results := make([]*models.Activity, len(keys))
			errors := make([]error, len(keys))

			activities, err := activityRepo.List(ctx, models.ActivityFilter{ActivityIDs: keys})
			if err != nil {
				for i := range errors {
					errors[i] = err
				}

				return results, errors
			}

			for i, key := range keys {
				found := false
				for j, activity := range activities {
					if activity.ID == key {
						found = true
						results[i] = activity

						activities[j] = activities[len(activities)-1]
						activities = activities[:len(activities)-1]

						break
					}
				}

				if !found {
					errors[i] = slerrors.NotFound("Activity")
				}
			}

			return results, errors
		},
		wait:     time.Millisecond / 2,
		maxBatch: 16,
	}
}