精简后的项目：仅保留 api/ui 源码、文档、构建依赖

api/dataloader/mediaURLLoader.go

@@ -0,0 +1,82 @@
+package dataloader
+
+import (
+	"time"
+
+	"github.com/photoview/photoview/api/graphql/models"
+	"github.com/photoview/photoview/api/scanner/media_type"
+	"github.com/pkg/errors"
+
+	"gorm.io/gorm"
+)
+
+func makeMediaURLLoader(db *gorm.DB, filter func(query *gorm.DB) *gorm.DB) func(keys []int) ([]*models.MediaURL, []error) {
+	return func(mediaIDs []int) ([]*models.MediaURL, []error) {
+
+		var urls []*models.MediaURL
+		query := db.Where("media_id IN (?)", mediaIDs)
+
+		query = filter(query)
+
+		if err := query.Find(&urls).Error; err != nil {
+			return nil, []error{errors.Wrap(err, "media url loader database query")}
+		}
+
+		resultMap := make(map[int]*models.MediaURL, len(mediaIDs))
+		for _, url := range urls {
+			resultMap[url.MediaID] = url
+		}
+
+		result := make([]*models.MediaURL, len(mediaIDs))
+		for i, mediaID := range mediaIDs {
+			mediaURL, found := resultMap[mediaID]
+			if found {
+				result[i] = mediaURL
+			} else {
+				result[i] = nil
+			}
+		}
+
+		return result, nil
+	}
+}
+
+func NewThumbnailMediaURLLoader(db *gorm.DB) *MediaURLLoader {
+	return &MediaURLLoader{
+		maxBatch: 100,
+		wait:     5 * time.Millisecond,
+		fetch: makeMediaURLLoader(db, func(query *gorm.DB) *gorm.DB {
+			return query.Where("purpose IN ?", []string{string(models.PhotoThumbnail), string(models.VideoThumbnail)})
+		}),
+	}
+}
+
+func NewHighresMediaURLLoader(db *gorm.DB) *MediaURLLoader {
+	return &MediaURLLoader{
+		maxBatch: 100,
+		wait:     5 * time.Millisecond,
+		fetch: makeMediaURLLoader(db, func(query *gorm.DB) *gorm.DB {
+			return query.
+				Where("(purpose = ? OR (purpose = ? AND content_type IN ?))", models.PhotoHighRes, models.MediaOriginal, media_type.WebMimetypes).
+				//PhotoHighRes consistently wins ordering when both exist, which is preferred for web delivery
+				Order("media_id ASC, CASE purpose WHEN '" +
+					string(models.MediaOriginal) + "' THEN 0 WHEN '" +
+					string(models.PhotoHighRes) + "' THEN 1 END ASC")
+		}),
+	}
+}
+
+func NewVideoWebMediaURLLoader(db *gorm.DB) *MediaURLLoader {
+	return &MediaURLLoader{
+		maxBatch: 100,
+		wait:     5 * time.Millisecond,
+		fetch: makeMediaURLLoader(db, func(query *gorm.DB) *gorm.DB {
+			return query.
+				Where("purpose IN ?", []string{string(models.VideoWeb), string(models.MediaOriginal)}).
+				//VideoWeb consistently wins ordering when both exist, which is preferred for web delivery
+				Order("media_id ASC, CASE purpose WHEN '" +
+					string(models.MediaOriginal) + "' THEN 0 WHEN '" +
+					string(models.VideoWeb) + "' THEN 1 END ASC")
+		}),
+	}
+}