我正在尝试计算帖子的观看次数，然后按观看次数排序帖子。
这是我尝试计算的代码部分。 Alias.views是一个对象数组。据我了解，alias.viewsCount应该是一个数字。
qb.loadRelationCountAndMap('alias.commentsCount', 'alias.comments');
qb.loadRelationCountAndMap('alias.votesCount', 'alias.voters');
qb.loadRelationCountAndMap('alias.viewsCount', 'alias.views');
qb.loadRelationCountAndMap('alias.sharesCount', 'alias.distributors');
qb.orderBy('alias.viewsCount', 'DESC');
但是我总是得到这个错误（日志）：
query: START TRANSACTION
query: SELECT "category"."id" AS "category_id", "category"."name" AS "category_name", "category"."slug" AS "category_slug" FROM "app_post_category" "category" INNER JOIN "app_post_category_post_type" "category_postTypes" ON "category_postTypes"."post_category_id"="category"."id" INNER JOIN "app_post_type" "postTypes" ON "postTypes"."id"="category_postTypes"."post_type_id" AND ("postTypes"."post_type" IN ($1, $2)) -- PARAMETERS: ["POST","ARTICLE"]
query: ROLLBACK
query: START TRANSACTION
[Nest] 923 - 05/30/2019, 4:47 PM [ExceptionsHandler] Cannot read property 'databaseName' of undefined +21439ms
TypeError: Cannot read property 'databaseName' of undefined
at /usr/src/app/src/query-builder/SelectQueryBuilder.ts:1866:145
at Array.map (<anonymous>)
at SelectQueryBuilder.createOrderByCombinedWithSelectExpression (/usr/src/app/src/query-builder/SelectQueryBuilder.ts:1861:14)
at SelectQueryBuilder.<anonymous> (/usr/src/app/src/query-builder/SelectQueryBuilder.ts:1779:46)
at step (/usr/src/app/node_modules/tslib/tslib.js:133:27)
at Object.next (/usr/src/app/node_modules/tslib/tslib.js:114:57)
at /usr/src/app/node_modules/tslib/tslib.js:107:75
at new Promise (<anonymous>)
at Object.__awaiter (/usr/src/app/node_modules/tslib/tslib.js:103:16)
at SelectQueryBuilder.executeEntitiesAndRawResults (/usr/src/app/node_modules/typeorm/query-builder/SelectQueryBuilder.js:1313:24)
是的，当我尝试按loadRelationCountAndMap的这4个字段中的任意一个进行排序时，就会出现错误
这是PostEntity和我获取帖子的全部功能：
export class PostEntity extends AbstractEntity {
@Column({name: 'title', nullable: true})
public title: string;
@Column('text', {name: 'content', nullable: true})
public content: string;
@Column({name: 'video_url', nullable: true})
public videoUrl: string;
@Column('json', {name: 'media', nullable: true})
public media: string[];
@Column('enum', {enum: PostStatus, name: 'status', default: PostStatus.IN_REVIEW})
public status: PostStatus;
@Column('enum', {enum: PostType, name: 'type', default: PostType.POST})
public type: PostType;
@ManyToOne(() => User, object => object.posts, {nullable: false, onDelete: 'CASCADE'})
@JoinColumn({name: 'author_id'})
public author: User;
@Column({name: 'author_id'})
public authorId: number;
@OneToMany(() => PostComment, object => object.post)
public comments: PostComment[];
@ManyToMany(() => User, object => object.votedPosts)
public voters: User[];
@ManyToMany(() => User, object => object.sharedPosts)
public distributors: User[];
@OneToMany(() => PostReport, postReport => postReport.post)
public reports: PostReport[];
@ManyToMany(() => TagEntity, object => object.posts, {cascade: ['insert', 'update']})
@JoinTable({
name: 'app_post_tags',
joinColumn: {name: 'post_id', referencedColumnName: 'id'},
inverseJoinColumn: {name: 'tag_id', referencedColumnName: 'id'}
})
public tags: TagEntity[];
@ManyToOne(() => PostCategory, object => object.posts, {nullable: true, onDelete: 'SET NULL'})
@JoinColumn({name: 'category_id'})
public category: PostCategory;
@ManyToOne(() => RewardTransfer, {nullable: true, onDelete: 'SET NULL'})
@JoinColumn({name: 'reward_id'})
public reward: RewardTransfer;
@ManyToMany(() => User, {cascade: ['insert', 'update']})
@JoinTable({
name: 'app_post_mentions',
joinColumn: {name: 'post_id', referencedColumnName: 'id'},
inverseJoinColumn: {name: 'user_id', referencedColumnName: 'id'}
})
public mentions: User[];
@OneToMany(() => Account, account => account.user)
public accounts: Account[];
@OneToMany(() => PostView, postView => postView.post)
public views: PostView[];
@OneToOne(() => PinnedPostEntity, object => object.post)
public pinnedPost: PinnedPostEntity;
}
public async findMany(request: Request, userId?: number): Promise<FeedDto[]> {
return getManager().transaction(async entityManager => {
const filter: IPostFeedQuery = request.query;
const qb = entityManager.createQueryBuilder(PostEntity, 'alias');
qb.leftJoin('alias.author', 'author')
.addSelect(['author.id', 'author.firstName', 'author.lastName', 'author.pictureUrl']);
qb.where('alias.status IN (:...statuses)', {
statuses: [PostStatus.PUBLISHED,
...(filter.userId && userId && filter.userId === userId ? [PostStatus.IN_REVIEW] : [])]
});
qb.leftJoinAndSelect('alias.category', 'category');
if (filter.userId) {
qb.andWhere('author.id = :authorId', {authorId: filter.userId});
}
if (filter.category) {
qb.andWhere('category.slug = :category', {category: filter.category});
}
if (filter.type) {
qb.andWhere('alias.type = :type', {type: filter.type});
} else {
qb.andWhere('alias.type <> :ignoredType', {ignoredType: PostType.FORUM_TOPIC});
}
if (filter.tag) {
qb.leftJoin('alias.tags', 'tags')
.andWhere('tags.slug = :tag', {tag: filter.tag});
}
qb.loadRelationCountAndMap('alias.commentsCount', 'alias.comments');
qb.loadRelationCountAndMap('alias.votesCount', 'alias.voters');
qb.loadRelationCountAndMap('alias.viewsCount', 'alias.views');
qb.loadRelationCountAndMap('alias.sharesCount', 'alias.distributors');
qb.orderBy('alias.viewsCount', 'DESC');
if (userId) {
qb.leftJoin(
'alias.voters',
'voters',
'voters.id = :userId', {userId}).addSelect(['voters.id']);
qb.leftJoin(
'alias.reports',
'reports',
'reports.reporter = :userId', {userId}).addSelect(['reports.createdAt']);
qb.leftJoin(
'alias.distributors',
'distributors',
'distributors.id = :userId', {userId}).addSelect(['distributors.id']);
}
const data = await this.apiService.setPagination<PostEntity>(request, qb);
return data.map(value => new FeedDto(value));
});
}
抱歉，代码太多，谢谢您的帮助。