MongoDB 架构设计 - 查找按用户过滤的所有博客文章中的最后 X 条评论
我正在尝试使用 Morphia 和 Play 框架重现一个 Post 到许多 Comment 的经典博客模式。
我在 Mongo 中的架构是：
{ "_id" : ObjectId("4d941c960c68c4e20d6a9abf"),
"className" : "models.Post",
"title" : "An amazing blog post",
"comments" : [
{
"commentDate" : NumberLong("1301552278491"),
"commenter" : {
"$ref" : "SiteUser",
"$id" : ObjectId("4d941c960c68c4e20c6a9abf")
},
"comment" : "What a blog post!"
},
{
"commentDate" : NumberLong("1301552278492"),
"commenter" : {
"$ref" : "SiteUser",
"$id" : ObjectId("4d941c960c68c4e20c6a9abf")
},
"comment" : "This is another comment"
}
]}
我正在尝试向博客引入社交网络方面，因此我希望能够在 SiteUser 的主页上提供该 的最后 X 条评论SiteUser 的所有帖子中的好友。
我的模型如下：
@Entity
public class Post extends Model {
public String title;
@Embedded
public List<Comment> comments;
}
@Embedded
public class Comment extends Model {
public long commentDate;
public String comment;
@Reference
public SiteUser commenter;
}
根据我在其他地方读到的内容，我我认为我需要对数据库运行以下命令（其中 [a, b, c] 代表 SiteUser）：
db.posts.find( { "comments.commenter" : {$in: [a, b, c]}} )
我有一个 List
- 在 Morphia 中为
Comments.commenter在Post上设置索引， - 实际上构建了以上查询
I am trying to reproduce the classic blog schema of one Post to many Comments using Morphia and the Play Framework.
My schema in Mongo is:
{ "_id" : ObjectId("4d941c960c68c4e20d6a9abf"),
"className" : "models.Post",
"title" : "An amazing blog post",
"comments" : [
{
"commentDate" : NumberLong("1301552278491"),
"commenter" : {
"$ref" : "SiteUser",
"$id" : ObjectId("4d941c960c68c4e20c6a9abf")
},
"comment" : "What a blog post!"
},
{
"commentDate" : NumberLong("1301552278492"),
"commenter" : {
"$ref" : "SiteUser",
"$id" : ObjectId("4d941c960c68c4e20c6a9abf")
},
"comment" : "This is another comment"
}
]}
I am trying to introduce a social networking aspect to the blog, so I would like to be able to provide on a SiteUser's homepage the last X comments by that SiteUser's friends, across all posts.
My models are as follows:
@Entity
public class Post extends Model {
public String title;
@Embedded
public List<Comment> comments;
}
@Embedded
public class Comment extends Model {
public long commentDate;
public String comment;
@Reference
public SiteUser commenter;
}
From what I have read elsewhere, I think I need to run the following against the database (where [a, b, c] represents the SiteUsers) :
db.posts.find( { "comments.commenter" : {$in: [a, b, c]}} )
I have a List<SiteUser> to pass in to Morphia for the filtering, but I don't know how to
- set up an index on
PostforComments.commenterfrom within Morphia - actually build the above query
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评论（1）
将
@Indexes(@Index("comments.commenter"))放在Post类上，或将@Indexed放在 <Comment类的 code>commenter 字段（Morphia 的Datastore.ensureIndexes()将在类中递归并正确创建comments.commentercode> Post 集合上的索引）我认为
ds.find(Post.class, "comments. “，用户）中的评论者可以工作，ds是一个数据存储，而用户是您的Listcode> （不过我不使用@Reference，所以我无法确认；你可能必须首先提取他们的Key列表。Either put
@Indexes(@Index("comments.commenter"))on thePostclass, or@Indexedon thecommenterfield of theCommentclass (Morphia'sDatastore.ensureIndexes()will recurse in the classes and correctly create thecomments.commenterindex on thePostcollection)I think
ds.find(Post.class, "comments.commenter in", users)would work,dsbeing aDatastoreandusersyourList<SiteUser>(I don't use@Referencethough, so I can't confirm; you might have to first extract the list of theirKeys).