Mongdb操作嵌套文档

1、一个文档如下

db.posts.find()

{
    "_id" : ObjectId("5388162dfc164ee1f39be37f"),
    "title" : "Java Example",
    "content" : "This is a example for Java!",
    "comments" : []
}

2、往_id等于"5388162dfc164ee1f39be37f"的文档中的comments插入数据

db.posts.update({"_id":ObjectId("5388162dfc164ee1f39be37f")},{$push:{"comments":{"content":"Good Article!","author":"Luxh"}}

　再插入一条

db.posts.update({"_id":ObjectId("5388162dfc164ee1f39be37f")},{$push:{"comments":{"content":"Not bad!","author":"Chuliuxiang"}}})

　结果如下

db.posts.find()

{
    "_id" : ObjectId("5388162dfc164ee1f39be37f"),
    "title" : "Java Example",
    "content" : "This is a example for Java!",
    "comments" : [
        {
            "content" : "Good Article!",
            "author" : "Luxh"
        },
        {
            "content" : "Not bad!",
            "author" : "Chuliuxiang"
        }
    ]
}

3、根据内嵌文档查询

　　1）查询出Luxh评论过的文章

db.posts.find({"comments.author":"Luxh"})

结果如下：
{
    "_id" : ObjectId("5388162dfc164ee1f39be37f"),
    "title" : "Java Example",
    "content" : "This is a example for Java!",
    "comments" : [
        {
            "content" : "Good Article!",
            "author" : "Luxh"
        },
        {
            "content" : "Not bad!",
            "author" : "Chuliuxiang"
        }
    ]
}

　　2）查询Luxh评论过的文章，返回指定的键

db.posts.find({"comments.author":"Luxh"},{"title":1,"content":1})

结果如下：

{
    "_id" : ObjectId("5388162dfc164ee1f39be37f"),
    "title" : "Java Example",
    "content" : "This is a example for Java!"
}

　　_id默认会返回。取消可设置"_id":0

4、修改

　　将author=Luxh评论的内容content修改为"I like it!"

db.posts.update({"comments.author":"Luxh"},{$set:{"comments.$.content":"I like it!"}})

结果如下：
{
    "_id" : ObjectId("5388162dfc164ee1f39be37f"),
    "title" : "Java Example",
    "content" : "This is a example for Java!",
    "comments" : [
        {
            "content" : "I like it!",
            "author" : "Luxh"
        },
        {
            "content" : "Not bad!",
            "author" : "Chuliuxiang"
        }
    ]
}

5、删除

　　删除comments中author=Luxh的记录

db.posts.update({},{$pull:{"comments":{"author":"Luxh"}}})

结果如下：

{
    "_id" : ObjectId("5388162dfc164ee1f39be37f"),
    "title" : "Java Example",
    "content" : "This is a example for Java!",
    "comments" : [
        {
            "content" : "Not bad!",
            "author" : "Chuliuxiang"
        }
    ]
}