我有这个示例 mongodb 文档 -
{
_id: 5db85ee97d9fb13ead4fc54c
applId: 5d48f34f7d9fb10ce171f905
fileId: "dd386cf7-4139-45c2-9853-cbb126621b51"
job: Object
country: "US"
fullName: "abcd xyz"
htmlWordCount: 2766
textWordCount: 1867
rchilliTextWordCount: 2840
deleted: 0
dateEntered: 2019-10-29 15:46:49.237
dateModified: 2019-10-29 15:46:49.237
}
我想在指南针中构建一个查询,以便在输出中包含以下字段 -
{
_id: 5db85ee97d9fb13ead4fc54c
country: "US"
fullName: "abcd xyz"
htmlWordCount: 2766
textWordCount: 1867
rchilliTextWordCount: 2840
winner: "rchilliTextWordCount"
}
请注意,它有一个名为“winner”的新字段,该字段始终返回具有最大字数的列(共 3 个“htmlWordCount”、“textWordCount”、“rchilliTextWordCount”
列)。这个新列“winner”
将在运行时查询时生成。此查询还会根据country = "US"
进行过滤。
如何在 MongoDB Compass 中执行此操作或者聚合管道应该是什么样子?
最佳答案
db.collection.aggregate([
{
$match: {
country: "US"
}
},
{
$project: {
country: 1,
fullName: 1,
htmlWordCount: 1,
textWordCount: 1,
rchilliTextWordCount: 1,
winner: {
$switch: {
branches: [
{
case: {
$and: [
{
$gt: [
"$htmlWordCount",
"$textWordCount"
]
},
{
$gt: [
"$htmlWordCount",
"$rchilliTextWordCount"
]
}
]
},
then: "htmlWordCount"
},
{
case: {
$and: [
{
$gt: [
"$textWordCount",
"$htmlWordCount"
]
},
{
$gt: [
"$textWordCount",
"$rchilliTextWordCount"
]
}
]
},
then: "textWordCount"
},
{
case: {
$and: [
{
$gt: [
"$rchilliTextWordCount",
"$htmlWordCount"
]
},
{
$gt: [
"$rchilliTextWordCount",
"$textWordCount"
]
}
]
},
then: "rchilliTextWordCount"
}
],
default: "No winners"
}
}
}
}
])
关于MongoDB compass - 从文档中的 3 个字段及其值中获取具有最大值的字段名称(键),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58614899/