将元素推入子文档中数组的任何位置 [英] Push element in any position of array in the subdocument

问题描述

在MongoDB 2.6中，我们可以使用$position( http://docs .mongodb.org/master/reference/operator/update/position/)修饰符，用于在文档中更新数组期间指定数组中的位置.但是我想在子文档中的数组中插入.

In MongoDB 2.6 we can use $position (http://docs.mongodb.org/master/reference/operator/update/position/) modifier to specifies the location in the array during update of an array in a document. But I would like to insert in an array in a subdocument.

文档架构:

{
  subdoc: {
    array: ['0', '1', '2', '5', '6']
  }
}

以下更新将元素压入array的末尾.

The following update pushes the elements in the end of array..

db.collection.update(
   { _id: tsId },
   {$push: { 'subdoc.array': { $each:['3', '4'], $position:3 } }});

所以，结果是

{
  subdoc: {
    array: ['0', '1', '2', '5', '6', '3', '4']
  }
}

但是我希望

{
  subdoc: {
    array: ['0', '1', '2', '3', '4', '5', '6']
  }
}

在MongoDB 2.6中可以吗?

Is it possible in MongoDB 2.6?

推荐答案

在您的问题中这是一个很合理的主张，但是您基本上认为这个概念是错误的.

It's a fair proposition in your question, however you basically have the concept wrong.

首先，您错过了以下概念:通常，数组的第一个元素的条目以0的索引开头，因此您的定位"以一个单位 >在这种情况下，应该是:

The first of which is that you have missed the concept that arrays in general have their entries starting at an index of 0 for the first element, so your "positioning" is out by one unit in this case and should have been:

db.collection.update(
   { _id: tsId },
   {$push: { 'subdoc.array': { "$each":["3", "4"], "$position": 3 } }}
)

由于您现在要插入正确的位置，因此元素位于正确的位置.

And since you are now inserting at the correct position, then your elements are in the correct place.

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