Meteor/Mongo 嵌套数组更新 | 嵌套数组更新

本文介绍了Meteor/Mongo 嵌套数组更新的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我是流星/mongo/js 作为堆栈的新手，我在 JSON 数组中迷失并引用它们.基于另一个SO答案(和文档)，我想我很接近...

I'm new to meteor/mongo/js as a stack and I'm getting lost in JSON arrays and referencing them. Based another SO answer ( and the docs) I think I am close...

Orders 集合中的一个文档，该文档具有嵌套数组.

A document in the Orders collection, the document has nested arrays.

Order -> orderLines -> lineItems:

示例文档:

{
"_id" : "27tGpRtMWYqPpFkDN",
"orderLines" : [
    {
        "lineId" : 1,
        "name" : "Cheese & Pickle",
        "instructions" : "",
        "lineItems" : [
            {
                "name" : "Cheddar Cheese",
                "quantity" : 1
            },
            {
                "name" : "Branston Pickle",
                "quantity" : 1
            },
            {
                "name" : "Focaccia Roll",
                "quantity" : 1
            }
        ]
    }
  ]
}

我试图从流星/mongo shell 做的事情:

What I'm trying to do from the meteor/mongo shell:

将foo"的指令"添加到 lineId = 1 的 orderLines
在 lineItems 数组上放置一个新项目

这似乎挂了...

meteor:PRIMARY> db.orders.update({_id:"27tGpRtMWYqPpFkDN","orderLines.lineId":"1", {$set: {"orderLines.$.instructions":"foo"}})
...

这不喜欢查询中的标识符

This doesn't like the identifier in the query

meteor:PRIMARY> db.orders.update({_id:"27tGpRtMWYqPpFkDN", "orderLines.lineId":"1"}, {$push:{"orderLines.$.lineItems":" { "name" : "butter", "quantity" : 1}"}});
2015-10-27T16:09:54.489+0100 SyntaxError: Unexpected identifier

推荐答案

感谢大家的意见...不过我找到了一些答案，贴出来供参考

Thanks all for your comments... but I found out some answers, posted for reference

项目 1 - 对数组中的值使用 $set

由于两个拼写错误而失败，一个在查询结束时缺少结束 }，第二个是在查询中引用 itemId 的值1".

This was failing due to two typos, one missing closing } at the end of the query, second was quoting the value "1" for itemId in the query.

这有效:

 db.orders.update({_id:"27tGpRtMWYqPpFkDN", orderLines.lineId":1},
 {$set: {"orderLines.$.instructions":"foo"}})

我还意识到，当我说它似乎挂起"时，是 cli 正在等待有效语句，因此提示缺少 } 或 )！

I also realised that when I said "It appears to hang" it is the cli waiting for a valid statement, so hints at a missing } or )!

项目 2 - 使用 $push 将数据添加到数组 - 2 层嵌套

由于引用数组数据而失败

This was failing due to quoting around the array data

db.orders.update({_id:"27tGpRtMWYqPpFkDN", "orderLines.lineId":1 },
{$push:{"orderLines.$.lineItems": { "name" : "butter", "quantity" : 1} }})

嵌套数组:可以使用 $ 位置运算符

我接下来要做的是在二级数组中的一个项目上使用 $set，这需要使用 $ 位置运算符两次:

What I want to do next is use $set on an item in the second level array, and this would require using the $ positional operator twice:

db.orders.update({"orderLines.lineId":1, lineItems.name:"Cheddar Cheese"},
{$set: {"orderLines.$.lineItems.$.quantity": 2}})

这会引发错误:

Too many positional (i.e. '$') elements found in path

有一个开放的 MongoDB 增强请求，但它自 2010 年以来一直开放

There is an open MongoDB enhancement request for this but it's been open since 2010

这篇关于Meteor/Mongo 嵌套数组更新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！