[英]How can I merge objects with the same key in an array in mongodb?
I derived the following data using the aggregate of mongodb.我使用 mongodb 的聚合得出以下数据。
{
"first_count": 2,
"second_count": 1,
"third_count": 2,
"test_count": 2,
"sido": "대구",
"guguns": [
{
"gugun": "남시",
"first_count": 1,
"second_count": 1,
"third_count": 1
},
{
"gugun": "부천군",
"first_count": 1,
"second_count": 0,
"third_count": 1
},
{
"gugun": "남시",
"test_count": 1
},
{
"gugun": "부천군",
"test_count": 1
}
]
}
This is the result of merging two facet data.这是合并两个方面数据的结果。 But the result I want is:
但我想要的结果是:
{
"first_count": 2,
"second_count": 1,
"third_count": 2,
"test_count": 2,
"sido": "대구",
"guguns": [
{
"gugun": "남시",
"first_count": 1,
"second_count": 1,
"third_count": 1,
"test_count": 1
},
{
"gugun": "부천군",
"first_count": 1,
"second_count": 0,
"third_count": 1,
"test_count": 1
}
]
}
How does guguns.gugun
combine the same values into one? guguns.gugun
如何将相同的值合并为一个? If possible, I would like to process it using mongodb aggregate.如果可能的话,我想使用 mongodb 聚合来处理它。
$unwind
deconstruct the guguns
array $unwind
解构guguns
数组$mergeObjects
to merge current object of guguns
with other $mergeObjects
合并的当前对象guguns
与其他$group
by _id
and guguns.gugun
property and get required fields first value and guguns
merged object $group
by _id
和guguns.gugun
属性并获取必填字段第一个值和guguns
合并对象$group
by only _id
and get required fields first value and construct the array of guguns
object $group
by only _id
并获取必填字段的第一个值并构造guguns
对象数组db.collection.aggregate([
{ $unwind: "$guguns" },
{
$group: {
_id: {
_id: "$_id",
gugun: "$guguns.gugun"
},
first_count: { $first: "$first_count" },
second_count: { $first: "$second_count" },
third_count: { $first: "$third_count" },
test_count: { $first: "$test_count" },
sido: { $first: "$sido" },
guguns: { $mergeObjects: "$guguns" }
}
},
{
$group: {
_id: "$_id._id",
first_count: { $first: "$first_count" },
second_count: { $first: "$second_count" },
third_count: { $first: "$third_count" },
test_count: { $first: "$test_count" },
sido: { $first: "$sido" },
guguns: { $push: "$guguns" }
}
}
])
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