使用推和切片更新数组 [英] Updating array with push and slice
问题描述
我刚刚开始使用MongoDB，并对我如何更新数据库中的文档有一些疑问.我在数据库中插入两个文档
I have just started to play with MongoDB and have some questions about how I update my documents in the database. I insert two documents in my db with
db.userscores.insert({name: 'John Doe', email: 'john.doe@mail.com', levels : [{level: 1, hiscores: [90, 40, 25], achivements: ['capture the flag', 'it can only be one', 'apple collector', 'level complete']}, {level: 2, hiscores: [30, 25], achivements: ['level complete']}, {level: 3, hiscores: [], achivements: []}]});
db.userscores.insert({name: 'Jane Doe', email: 'jane.doe@mail.com', levels : [{level: 1, hiscores: [150, 90], achivements: ['Master of the universe', 'capture the flag', 'it can only be one', 'apple collector', 'level complete']}]});
我检查插入是否可以使用find()命令，看起来还可以.
I check if my inserting worked with the find() command and it looks ok.
db.userscores.find().pretty();
{
"_id" : ObjectId("5358b47ab826096525d0ec98"),
"name" : "John Doe",
"email" : "john.doe@mail.com",
"levels" : [
{
"level" : 1,
"hiscores" : [
90,
40,
25
],
"achivements" : [
"capture the flag",
"it can only be one",
"apple collector",
"level complete"
]
},
{
"level" : 2,
"hiscores" : [
30,
25
],
"achivements" : [
"level complete"
]
},
{
"level" : 3,
"hiscores" : [ ],
"achivements" : [ ]
}
]
}
{
"_id" : ObjectId("5358b47ab826096525d0ec99"),
"name" : "Jane Doe",
"email" : "jane.doe@mail.com",
"levels" : [
{
"level" : 1,
"hiscores" : [
150,
90
],
"achivements" : [
"Master of the universe",
"capture the flag",
"it can only be one",
"apple collector",
"level complete"
]
}
]
}
如何向我的用户分数添加/更新数据?可以说我想在级别1上向用户John Doe添加一个hiscore.如何插入hiscore 75并仍然对hiscore数组进行排序?我可以限制hiscores的数量，以便数组仅包含3个元素吗?我已经尝试过
How can I add/update data to my userscores? Lets say I want to add a hiscore to user John Doe on level 1. How do I insert the hiscore 75 and still have the hiscore array sorted? Can I limit the number of hiscores so the array only contains 3 elements? I have tried with
db.userscores.aggregate(
// Initial document match (uses name, if a suitable one is available)
{ $match: {
name : 'John Doe'
}},
// Expand the levels array into a stream of documents
{ $unwind: '$levels' },
// Filter to 'level 1' scores
{ $match: {
'levels.level': 1
}},
// Add score 75 with cap/limit of 3 elements
{ $push: {
'levels.hiscore':{$each [75], $slice:-3}
}}
);
但是它不起作用，我得到的错误是"SyntaxError:意外令牌[".
but it wont work, the error I get is "SyntaxError: Unexpected token [".
而且，例如，我如何从1级的所有用户获得10分最高的分数?我的文档方案可以吗，或者我可以使用更好的方案来存储用户游戏中不同级别的分数和成就?使用上述方案在查询或性能方面有不利之处吗?
And also, how do I get the 10 highest score from all users on level 1 for example? Is my document scheme ok or can I use a better scheme for storing users hiscores and achivements on diffrent levels for my game? Is there any downsides on quering or performance using they scheme above?
推荐答案
您可以使用以下语句添加分数:
You can add the score with this statement:
db.userscores.update(
{ "name": "John Doe", "levels.level": 1 },
{ "$push": { "levels.$.hiscores": 75 } } )
这将不对数组进行排序，因为仅当您的数组元素是文档时才支持.
This will not sort the array as this is only supported if your array elements are documents.
在MongoDB 2.6中，您还可以对非文档数组使用排序:
In MongoDB 2.6 you can use sorting also for non-document arrays:
db.userscores.update(
{ "name": "John Doe", "levels.level": 1 },
{ "$push": { "levels.$.hiscores": { $each: [ 75 ], $sort: -1, $slice: 3 } } } )
这篇关于使用推和切片更新数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
