Ember关联关系 #

// app/models/user.js
import Model, { attr, hasOne } from '@ember-data/model';

export default class UserModel extends Model {
  @attr('string') name;
  @hasOne('profile') profile;
}

// app/models/profile.js
import Model, { attr, belongsTo } from '@ember-data/model';

export default class ProfileModel extends Model {
  @attr('string') bio;
  @belongsTo('user') user;
}

// 获取关联
const profile = await user.profile;

// 设置关联
user.profile = newProfile;
await user.save();

// app/models/post.js
import Model, { attr, hasMany } from '@ember-data/model';

export default class PostModel extends Model {
  @attr('string') title;
  @hasMany('comment') comments;
}

// app/models/comment.js
import Model, { attr, belongsTo } from '@ember-data/model';

export default class CommentModel extends Model {
  @attr('string') body;
  @belongsTo('post') post;
}

// 获取所有评论
const comments = await post.comments;

// 添加评论
const comment = this.store.createRecord('comment', {
  body: 'Great post!',
  post: post,
});
await comment.save();

// 遍历评论
for (const comment of comments) {
  console.log(comment.body);
}

// app/models/post.js
export default class PostModel extends Model {
  @hasMany('comment', { inverse: 'post' }) comments;
}

// app/models/comment.js
export default class CommentModel extends Model {
  @belongsTo('post', { inverse: 'comments' }) post;
}

// app/models/post.js
import Model, { attr, hasMany } from '@ember-data/model';

export default class PostModel extends Model {
  @attr('string') title;
  @hasMany('tag') tags;
}

// app/models/tag.js
import Model, { attr, hasMany } from '@ember-data/model';

export default class TagModel extends Model {
  @attr('string') name;
  @hasMany('post') posts;
}

// 添加标签
post.tags.pushObject(tag);
await post.save();

// 移除标签
post.tags.removeObject(tag);
await post.save();

// 获取所有标签
const tags = await post.tags;

export default class PostModel extends Model {
  @belongsTo('user', { async: true }) author;
  @hasMany('comment', { async: true }) comments;
}

{{! 使用await}}
<p>作者：{{await @post.author.name}}</p>

{{#each (await @post.comments) as |comment|}}
  <p>{{comment.body}}</p>
{{/each}}

const author = await post.author;
const comments = await post.comments;

// 异步加载（默认）
@belongsTo('user', { async: true }) author;

// 同步加载
@belongsTo('user', { async: false }) author;

// 显式指定反向关联
@hasMany('comment', { inverse: 'post' }) comments;

// 禁用反向关联
@hasMany('comment', { inverse: null }) comments;

// 多态关联
export default class CommentModel extends Model {
  @attr('string') body;
  @belongsTo('commentable', { polymorphic: true }) commentable;
}

// 被关联的模型
export default class PostModel extends Model {
  @hasMany('comment', { as: 'commentable' }) comments;
}

export default class PhotoModel extends Model {
  @hasMany('comment', { as: 'commentable' }) comments;
}

// 获取关联ID（不加载）
const authorId = post.belongsTo('author').id();

// 检查关联是否存在
const hasAuthor = post.belongsTo('author').value() !== null;

// 加载关联
const author = await post.author;

// 设置belongsTo
post.author = newUser;

// 添加hasMany
post.comments.pushObject(newComment);

// 移除hasMany
post.comments.removeObject(comment);

// 清空hasMany
post.comments.clear();

// 检查是否已加载
const isLoaded = post.hasMany('comments').value() !== null;

// 检查是否正在加载
const isLoading = post.hasMany('comments').isLoading();

// 检查是否有未保存更改
const hasChanged = post.hasMany('comments').hasBeenFetched();

// app/routes/posts/show.js
model(params) {
  return this.store.findRecord('post', params.post_id, {
    include: 'author,comments',
  });
}

model(params) {
  return this.store.findRecord('post', params.post_id, {
    include: 'author,comments.author,comments.likes',
  });
}

// app/models/category.js
import Model, { attr, belongsTo, hasMany } from '@ember-data/model';

export default class CategoryModel extends Model {
  @attr('string') name;
  @belongsTo('category', { inverse: 'children' }) parent;
  @hasMany('category', { inverse: 'parent' }) children;
}

// 获取父分类
const parent = await category.parent;

// 获取子分类
const children = await category.children;

// 设置父分类
category.parent = parentCategory;
await category.save();

// 推荐 - 异步关联
@belongsTo('user', { async: true }) author;

// 仅在必要时使用同步关联
@belongsTo('user', { async: false }) author;

// 好的做法 - 明确指定
@hasMany('comment', { inverse: 'post' }) comments;
@belongsTo('post', { inverse: 'comments' }) post;

// 避免 - 依赖隐式推断
@hasMany('comment') comments;
@belongsTo('post') post;

// 好的做法 - 预加载
model(params) {
  return this.store.findRecord('post', params.post_id, {
    include: 'author,comments',
  });
}

// 避免 - N+1查询
model(params) {
  return this.store.findRecord('post', params.post_id);
  // 然后在模板中逐个加载关联
}