這是我正在使用的查找查詢
{
$lookup: {
from: 'weeks',
localField: 'weeks',
foreignField: '_id',
as: 'weeks'
}
}
Result with this query
"weeks": [
{
"_id": "619e87d7b1bd6501c7aae286",
"name": "week-1",
"description": "Commodo in o.",
"course": "619e87d7b1bd6501c7aae281",
"days": [
"619e87dab1bd6501c7aae2a8",
"619e87dab1bd6501c7aae2a9",
"619e87dab1bd6501c7aae2aa",
"619e87dab1bd6501c7aae2ab",
"619e87dab1bd6501c7aae2ac",
"619e87dab1bd6501c7aae2ad"
],
"isCopy": false,
"__v": 0
},
{
"_id": "619e87d7b1bd6501c7aae287",
"name": "week-2",
"description": "Irure e.",
"course": "619e87d7b1bd6501c7aae281",
"days": [
"619e87dab1bd6501c7aae2db",
"619e87dab1bd6501c7aae2dc",
"619e87dab1bd6501c7aae2dd",
"619e87dab1bd6501c7aae2de",
"619e87dab1bd6501c7aae2df",
"619e87dab1bd6501c7aae2e0"
],
"isCopy": false,
"__v": 0
},]
在上面的查找中，localField 周是一個物件 Id 的陣列。當我執行此代碼時，它按預期作業，但我想對管道使用相同的功能。這是我寫的代碼
{
$lookup: {
from: "weeks",
let: { wks: "$weeks" },
pipeline: [
{
$match: {
_id: {
$in: ["$$wks"]
}
}
}
],
as: "weeks"
}
}
Result with this query `weeks:[]`
當我運行它時，我沒有得到任何輸出，我認為原因是周陣列被解釋為字串而不是物件 id。
我現在如何解決它...
uj5u.com熱心網友回復：
這是你需要的嗎？在下面檢查我的 mongoplayground，如果沒有，請制作您自己的示例資料并與我分享一個新鏈接。
db.collection.aggregate([
{
$lookup: {
from: "weeks",
let: {
wks: "$weeks"
},
pipeline: [
{
$match: {
$expr: {
$in: [
"$_id",
"$$wks"
]
}
}
}
],
as: "weeks"
}
}
])
mongoplayground
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