MongoDB 无法根据可变父文档查找文档 属性
MongoDB unable to lookup docs based on variable parent document property
我想找到 products 并为每个产品附加 deals。 deal 是来自同一集合的 product，但基于一些共同的属性。
因此，根据我的要求管道应该 return 文档，对于每个文档找到其他产品，这些产品与当前的产品不同，但具有相同的 detail.duration。但是即使我有很多持续时间相同的文档，deals 总是 []。你能找出我管道的问题吗？
以下是我 运行 的聚合管道：
为了清楚起见，我根据下面显示的文档添加了过滤器 _id $in。这不是真实管道 $match 查询的一部分。
db.products
.aggregate([
{
$match: {
_id: {
$in: [
ObjectId("6210fa8746bee3fcbd0ad062"),
ObjectId("6210fa7c46bee3fcbd0acc21"),
],
},
"detail.duration": { $gt: 0 },
},
},
{
$lookup: {
from: "products",
let: { id: "$_id", duration: "$detail.duration" },
as: "deals",
pipeline: [
{
$match: {
_id: { $ne: "$id" },
"detail.duration": "$duration",
},
},
{ $project: { detail: 1 } },
{ $limit: 1 },
],
},
},
{ $limit: 2 },
{ $project: { deals: 1 } },
])
.pretty();
这是结果：
{ "_id" : ObjectId("6210fa7c46bee3fcbd0acc21"), "deals" : [ ] }
{ "_id" : ObjectId("6210fa8746bee3fcbd0ad062"), "deals" : [ ] }
以下是集合中的两个示例文档：
{
"_id" : ObjectId("6210fa8746bee3fcbd0ad062"),
"book" : "https://wegotrip.com/en/paris-d3/muse-d-orsay-and-musee-de-l-orangerie-combined-tour-ticket-p1117/?SUB_ID=336264",
"address" : "Rue de Lille, 62bis",
"countryName" : "France",
"cityName" : "Paris",
"location" : {
"lang" : 48.859886,
"lat" : 2.3254821,
"country" : ObjectId("6210fa7746bee3fcbd0aca20"),
"city" : ObjectId("6210fa7746bee3fcbd0aca1c"),
"location" : "Rue de Lille, 62bis",
"_id" : ObjectId("6210fa8746bee3fcbd0ad063")
},
"includes" : [
{
"value" : "Skip-the-line ticket to Orsay Museum",
"included" : true
},
{
"value" : "Skip-the-line ticket to the Musée de l'Orangerie",
"included" : true
},
{
"value" : "Detailed description of the Nymphéas from Claude Monet",
"included" : true
},
{
"value" : "Interesting stories of many great artists and their lives",
"included" : true
},
{
"value" : "An easy walkthrough of the Musée d'Orsay and the Musée de l'Orangerie and their great collection",
"included" : true
},
{
"value" : "Headphones — you should bring your own",
"included" : false
}
],
"price" : {
"priceConcession" : null,
"priceChild" : null,
"price" : 57,
"currency" : ObjectId("6210fa7746bee3fcbd0aca2f"),
"_id" : ObjectId("6210fa8746bee3fcbd0ad064")
},
"detail" : {
"isPass" : false,
"features" : [
{
"key" : "audio_guide",
"value" : "Audio Guide"
}
],
"highlights" : [
"Admire the masterpieces by Monet, Renoir, Degas, Cézanne, and many more",
"Discover one of the finest collections of Impressionist art in the world",
"Visit the Nymphéas by Monet, one of the greatest pieces of Impressionism",
"Explore the Guillaume and Walter collection and find out what makes it unique"
],
"details" : [ ],
"images" : [
{
"id" : 7270,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/dsc04800/01d0770dcc0cac4c6de0f6eae70742f6.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/dsc04800.jpg"
},
{
"id" : 7269,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/nympheasannees30salle1parisiennephotorogerviolet/e1270aef1c01391290df71d1f83c8abc.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/nympheasannees30salle1parisiennephotorogerviolet.jpg"
},
{
"id" : 7268,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/ob1f7c80dsc02414-large/7712cb29e133ee3acb4b2bffbc2ac654.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/ob1f7c80dsc02414-large.jpg"
},
{
"id" : 7267,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/tuileriesgardensb16dsc00678talrg/47430ab8a257e3ccd2337d7a0d750c57.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/tuileriesgardensb16dsc00678talrg.jpg"
},
{
"id" : 7266,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/009/54223ef27aac5cd94fe5c20893abf2de.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/009.jpg"
},
{
"id" : 7264,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/monet-morning-with-weeping-willow/09bf842cc9a9d7eade8d0739f704699f.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/monet-morning-with-weeping-willow.jpg"
}
],
"duration" : 2,
"_id" : ObjectId("6210fa8746bee3fcbd0ad065")
},
"availability" : null,
"subcategory" : [
{
"id" : 6,
"title" : "Sightseeing Tickets & Passes",
"slug" : "sightseeing-tickets-passes"
}
],
"category" : [
{
"id" : 6,
"title" : "Sightseeing Tickets & Passes",
"slug" : "sightseeing-tickets-passes"
}
],
"type" : "Audio Guide",
"description" : "Visit the famous Musee d'Orsay and Musée de l'Orangerie in Paris with this combined self-guided tour! \r\n\r\nNavigate through the maze of exhibition rooms with mobile app and see a collection of works by the Impressionists and Expressionists – Seurat, Cezanne, Gaugin, Monet, Renoir, Manet, Van Gogh, Degas; sculptors like Rodin, Pompon and others. Check out a mini-version of the Statue of Liberty! \r\n\r\nExplore the Nymphéas paintings by Claude Monet, that is called \"the Sistine chapel of Impressionism\". Admire the great works of Picasso, Soutine, Rousseau, Matisse and many others part of the Paul Guillaume and Jean Walter collection. Learn about the style and private life of the artists.\r\n\r\nThe audio-guide will provide you with all the information on the cultural significance of these paintings. Walking through rooms you will understand how revolutionary for those times Manet’s, Cezanne’s and Degas’ creation really was casting doubts on conservative, academic conceptions of 'true art' and offering new techniques and ideas.",
"thumbnail" : "https://app.wegotrip.com/media/CACHE/images/store/1117/013/c0b8cce52cb61ab1f30872e6e93385b4.jpg",
"name" : "Musée d'Orsay/Musée de l'Orangerie Combined Admission Ticket & Audio Tour",
"attractionDescription" : "",
"attractionName" : "Musée d'Orsay & Musée de l'Orangerie",
"attraction" : ObjectId("6210fa8746bee3fcbd0ad056"),
"provider" : {
"rating" : {
"count" : 0,
"average" : null,
"_id" : ObjectId("6210fa8746bee3fcbd0ad067")
},
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/013/c0b8cce52cb61ab1f30872e6e93385b4.jpg",
"slug" : "muse-d-orsay-and-musee-de-l-orangerie-combined-tour-ticket",
"id" : "1117",
"key" : "1",
"_id" : ObjectId("6210fa8746bee3fcbd0ad066")
},
"__v" : 0
}
{
"_id" : ObjectId("6210fa7c46bee3fcbd0acc21"),
"book" : "https://wegotrip.com/en/barcelona-d1/the-dali-museum-in-figueres-p3/?SUB_ID=336264",
"address" : "Pujada del Castell, 43",
"countryName" : "Spain",
"cityName" : "Barcelona",
"location" : {
"lang" : 42.26829425831263,
"lat" : 2.95884132385254,
"country" : ObjectId("6210fa7746bee3fcbd0aca3e"),
"city" : ObjectId("6210fa7746bee3fcbd0aca3a"),
"location" : "Pujada del Castell, 43",
"_id" : ObjectId("6210fa7c46bee3fcbd0acc22")
},
"includes" : [
{
"value" : "Recommendations of places to visit to understand the life of Dali better",
"included" : true
},
{
"value" : "Skip-the-line ticket to Dali Theatre-Museum",
"included" : true
},
{
"value" : "Headphones — you should bring your own",
"included" : false
}
],
"price" : {
"priceConcession" : null,
"priceChild" : null,
"price" : 33,
"currency" : ObjectId("6210fa7746bee3fcbd0aca2f"),
"_id" : ObjectId("6210fa7c46bee3fcbd0acc23")
},
"detail" : {
"isPass" : false,
"features" : [
{
"key" : "audio_guide",
"value" : "Audio Guide"
}
],
"highlights" : [
"Discover Dali's surrealism starting with the building of the museum — it's definitely one of a kind",
"Inside the museum you'll find the most famous and controversial works of the artist",
"Our tour will provide you with insights and exiting facts about Dali's works"
],
"details" : [ ],
"images" : [
{
"id" : 6916,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/3/figueres-oleguer2/032b55c27bb2cd119bdc7fe6c4b86491.jpeg",
"full" : "https://app.wegotrip.com/media/store/3/figueres-oleguer2.jpeg"
},
{
"id" : 6915,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/3/sky-monument-statue-golden-museum-yellow-1156442-pxherecom/28c645449a9f45ec1e8ede7b7ffbe30f.jpg",
"full" : "https://app.wegotrip.com/media/store/3/sky-monument-statue-golden-museum-yellow-1156442-pxherecom.jpg"
},
{
"id" : 6914,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/3/architecture-window-museum-landmark-surrealism-catalonia-800928-pxherecom/43691ba6aecc2ee084c300c150e32a03.jpg",
"full" : "https://app.wegotrip.com/media/store/3/architecture-window-museum-landmark-surrealism-catalonia-800928-pxherecom.jpg"
},
{
"id" : 831,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/3/figueres-oleguers3k6yoz/b9c3093c79cf50e621e022706af59ad6.jpg",
"full" : "https://app.wegotrip.com/media/store/3/figueres-oleguers3k6yoz.jpg"
},
{
"id" : 832,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/3/shutterstock82210018/2a2450d4f75edf4549d36f2286b6f19b.jpg",
"full" : "https://app.wegotrip.com/media/store/3/shutterstock82210018.jpg"
},
{
"id" : 833,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/3/dali-museum-8983261920/aa0d93e475c7b7388bee88ff14f8d795.jpg",
"full" : "https://app.wegotrip.com/media/store/3/dali-museum-8983261920.jpg"
},
{
"id" : 834,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/3/shutterstock196896461/74fc427d0a27f0aa199ed24f4c51bcc5.jpg",
"full" : "https://app.wegotrip.com/media/store/3/shutterstock196896461.jpg"
}
],
"duration" : 2,
"_id" : ObjectId("6210fa7c46bee3fcbd0acc24")
},
"availability" : null,
"subcategory" : [
{
"id" : 3,
"title" : "Theme Tours",
"slug" : "theme-tours"
},
{
"id" : 1,
"title" : "Culture & History",
"slug" : "culture-and-history"
},
{
"id" : 6,
"title" : "Sightseeing Tickets & Passes",
"slug" : "sightseeing-tickets-passes"
}
],
"category" : [
{
"id" : 3,
"title" : "Theme Tours",
"slug" : "theme-tours"
},
{
"id" : 1,
"title" : "Culture & History",
"slug" : "culture-and-history"
},
{
"id" : 6,
"title" : "Sightseeing Tickets & Passes",
"slug" : "sightseeing-tickets-passes"
}
],
"type" : "Audio Guide",
"description" : "The Dalí Theatre and Museum is a museum of the artist Salvador Dalí in his home town of Figueres, in Catalonia, Spain. Dalí is buried there in a crypt below the stage. \r\n\r\nImmerse yourself in an exciting journey through the world of the genius of surrealism. Reveal the meaning of his ambiguous creations and learn the history of the artist's life. Enjoy the unique world of Dali in this excursion.",
"thumbnail" : "https://app.wegotrip.com/media/CACHE/images/store/001_Ispaniya_Figeras_Teatr-01/783c3a10c34eb40c29f14f704cd9c8d1.jpeg",
"name" : "The Dali Theatre-Museum: Skip-the-Line & Audio Tour",
"attractionDescription" : "",
"attractionName" : "Dali Theatre and Museum",
"attraction" : ObjectId("6210fa7c46bee3fcbd0acc15"),
"provider" : {
"rating" : {
"count" : 0,
"average" : null,
"_id" : ObjectId("6210fa7c46bee3fcbd0acc26")
},
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/001_Ispaniya_Figeras_Teatr-01/783c3a10c34eb40c29f14f704cd9c8d1.jpeg",
"slug" : "the-dali-museum-in-figueres",
"id" : "3",
"key" : "1",
"_id" : ObjectId("6210fa7c46bee3fcbd0acc25")
},
"__v" : 0
}
以上两者都将 detail.duration 设置为 2 并且根据查询，这两个应该被视为交易并在结果文档中找到，但是查询 return s deals: []，一个空数组。我无法找出问题所在。
The $match query syntax is identical to the read operation query syntax; i.e. $match does not accept raw aggregation expressions. To include aggregation expression in $match, use a $expr query expression.
并且需要使用$$获取变量值
To reference variables in pipeline stages, use the "$$" syntax.
将管道中的 $match 阶段更改为：
{
$match: {
_id: {
$ne: "$$id"
},
$expr: {
$eq: [
"$detail.duration",
"$$duration"
]
}
}
}
我想找到 products 并为每个产品附加 deals。 deal 是来自同一集合的 product，但基于一些共同的属性。
因此，根据我的要求管道应该 return 文档，对于每个文档找到其他产品，这些产品与当前的产品不同，但具有相同的 detail.duration。但是即使我有很多持续时间相同的文档，deals 总是 []。你能找出我管道的问题吗？
以下是我 运行 的聚合管道： 为了清楚起见，我根据下面显示的文档添加了过滤器 _id $in。这不是真实管道 $match 查询的一部分。
db.products
.aggregate([
{
$match: {
_id: {
$in: [
ObjectId("6210fa8746bee3fcbd0ad062"),
ObjectId("6210fa7c46bee3fcbd0acc21"),
],
},
"detail.duration": { $gt: 0 },
},
},
{
$lookup: {
from: "products",
let: { id: "$_id", duration: "$detail.duration" },
as: "deals",
pipeline: [
{
$match: {
_id: { $ne: "$id" },
"detail.duration": "$duration",
},
},
{ $project: { detail: 1 } },
{ $limit: 1 },
],
},
},
{ $limit: 2 },
{ $project: { deals: 1 } },
])
.pretty();
这是结果：
{ "_id" : ObjectId("6210fa7c46bee3fcbd0acc21"), "deals" : [ ] }
{ "_id" : ObjectId("6210fa8746bee3fcbd0ad062"), "deals" : [ ] }
以下是集合中的两个示例文档：
{
"_id" : ObjectId("6210fa8746bee3fcbd0ad062"),
"book" : "https://wegotrip.com/en/paris-d3/muse-d-orsay-and-musee-de-l-orangerie-combined-tour-ticket-p1117/?SUB_ID=336264",
"address" : "Rue de Lille, 62bis",
"countryName" : "France",
"cityName" : "Paris",
"location" : {
"lang" : 48.859886,
"lat" : 2.3254821,
"country" : ObjectId("6210fa7746bee3fcbd0aca20"),
"city" : ObjectId("6210fa7746bee3fcbd0aca1c"),
"location" : "Rue de Lille, 62bis",
"_id" : ObjectId("6210fa8746bee3fcbd0ad063")
},
"includes" : [
{
"value" : "Skip-the-line ticket to Orsay Museum",
"included" : true
},
{
"value" : "Skip-the-line ticket to the Musée de l'Orangerie",
"included" : true
},
{
"value" : "Detailed description of the Nymphéas from Claude Monet",
"included" : true
},
{
"value" : "Interesting stories of many great artists and their lives",
"included" : true
},
{
"value" : "An easy walkthrough of the Musée d'Orsay and the Musée de l'Orangerie and their great collection",
"included" : true
},
{
"value" : "Headphones — you should bring your own",
"included" : false
}
],
"price" : {
"priceConcession" : null,
"priceChild" : null,
"price" : 57,
"currency" : ObjectId("6210fa7746bee3fcbd0aca2f"),
"_id" : ObjectId("6210fa8746bee3fcbd0ad064")
},
"detail" : {
"isPass" : false,
"features" : [
{
"key" : "audio_guide",
"value" : "Audio Guide"
}
],
"highlights" : [
"Admire the masterpieces by Monet, Renoir, Degas, Cézanne, and many more",
"Discover one of the finest collections of Impressionist art in the world",
"Visit the Nymphéas by Monet, one of the greatest pieces of Impressionism",
"Explore the Guillaume and Walter collection and find out what makes it unique"
],
"details" : [ ],
"images" : [
{
"id" : 7270,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/dsc04800/01d0770dcc0cac4c6de0f6eae70742f6.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/dsc04800.jpg"
},
{
"id" : 7269,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/nympheasannees30salle1parisiennephotorogerviolet/e1270aef1c01391290df71d1f83c8abc.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/nympheasannees30salle1parisiennephotorogerviolet.jpg"
},
{
"id" : 7268,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/ob1f7c80dsc02414-large/7712cb29e133ee3acb4b2bffbc2ac654.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/ob1f7c80dsc02414-large.jpg"
},
{
"id" : 7267,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/tuileriesgardensb16dsc00678talrg/47430ab8a257e3ccd2337d7a0d750c57.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/tuileriesgardensb16dsc00678talrg.jpg"
},
{
"id" : 7266,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/009/54223ef27aac5cd94fe5c20893abf2de.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/009.jpg"
},
{
"id" : 7264,
"description" : "",
"cover" : false,
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/monet-morning-with-weeping-willow/09bf842cc9a9d7eade8d0739f704699f.jpg",
"full" : "https://app.wegotrip.com/media/store/1117/monet-morning-with-weeping-willow.jpg"
}
],
"duration" : 2,
"_id" : ObjectId("6210fa8746bee3fcbd0ad065")
},
"availability" : null,
"subcategory" : [
{
"id" : 6,
"title" : "Sightseeing Tickets & Passes",
"slug" : "sightseeing-tickets-passes"
}
],
"category" : [
{
"id" : 6,
"title" : "Sightseeing Tickets & Passes",
"slug" : "sightseeing-tickets-passes"
}
],
"type" : "Audio Guide",
"description" : "Visit the famous Musee d'Orsay and Musée de l'Orangerie in Paris with this combined self-guided tour! \r\n\r\nNavigate through the maze of exhibition rooms with mobile app and see a collection of works by the Impressionists and Expressionists – Seurat, Cezanne, Gaugin, Monet, Renoir, Manet, Van Gogh, Degas; sculptors like Rodin, Pompon and others. Check out a mini-version of the Statue of Liberty! \r\n\r\nExplore the Nymphéas paintings by Claude Monet, that is called \"the Sistine chapel of Impressionism\". Admire the great works of Picasso, Soutine, Rousseau, Matisse and many others part of the Paul Guillaume and Jean Walter collection. Learn about the style and private life of the artists.\r\n\r\nThe audio-guide will provide you with all the information on the cultural significance of these paintings. Walking through rooms you will understand how revolutionary for those times Manet’s, Cezanne’s and Degas’ creation really was casting doubts on conservative, academic conceptions of 'true art' and offering new techniques and ideas.",
"thumbnail" : "https://app.wegotrip.com/media/CACHE/images/store/1117/013/c0b8cce52cb61ab1f30872e6e93385b4.jpg",
"name" : "Musée d'Orsay/Musée de l'Orangerie Combined Admission Ticket & Audio Tour",
"attractionDescription" : "",
"attractionName" : "Musée d'Orsay & Musée de l'Orangerie",
"attraction" : ObjectId("6210fa8746bee3fcbd0ad056"),
"provider" : {
"rating" : {
"count" : 0,
"average" : null,
"_id" : ObjectId("6210fa8746bee3fcbd0ad067")
},
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/1117/013/c0b8cce52cb61ab1f30872e6e93385b4.jpg",
"slug" : "muse-d-orsay-and-musee-de-l-orangerie-combined-tour-ticket",
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{
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"address" : "Pujada del Castell, 43",
"countryName" : "Spain",
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"_id" : ObjectId("6210fa7c46bee3fcbd0acc22")
},
"includes" : [
{
"value" : "Recommendations of places to visit to understand the life of Dali better",
"included" : true
},
{
"value" : "Skip-the-line ticket to Dali Theatre-Museum",
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{
"value" : "Headphones — you should bring your own",
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"currency" : ObjectId("6210fa7746bee3fcbd0aca2f"),
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},
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"isPass" : false,
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{
"key" : "audio_guide",
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}
],
"highlights" : [
"Discover Dali's surrealism starting with the building of the museum — it's definitely one of a kind",
"Inside the museum you'll find the most famous and controversial works of the artist",
"Our tour will provide you with insights and exiting facts about Dali's works"
],
"details" : [ ],
"images" : [
{
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{
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{
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}
],
"duration" : 2,
"_id" : ObjectId("6210fa7c46bee3fcbd0acc24")
},
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"subcategory" : [
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"title" : "Theme Tours",
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},
{
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"title" : "Culture & History",
"slug" : "culture-and-history"
},
{
"id" : 6,
"title" : "Sightseeing Tickets & Passes",
"slug" : "sightseeing-tickets-passes"
}
],
"category" : [
{
"id" : 3,
"title" : "Theme Tours",
"slug" : "theme-tours"
},
{
"id" : 1,
"title" : "Culture & History",
"slug" : "culture-and-history"
},
{
"id" : 6,
"title" : "Sightseeing Tickets & Passes",
"slug" : "sightseeing-tickets-passes"
}
],
"type" : "Audio Guide",
"description" : "The Dalí Theatre and Museum is a museum of the artist Salvador Dalí in his home town of Figueres, in Catalonia, Spain. Dalí is buried there in a crypt below the stage. \r\n\r\nImmerse yourself in an exciting journey through the world of the genius of surrealism. Reveal the meaning of his ambiguous creations and learn the history of the artist's life. Enjoy the unique world of Dali in this excursion.",
"thumbnail" : "https://app.wegotrip.com/media/CACHE/images/store/001_Ispaniya_Figeras_Teatr-01/783c3a10c34eb40c29f14f704cd9c8d1.jpeg",
"name" : "The Dali Theatre-Museum: Skip-the-Line & Audio Tour",
"attractionDescription" : "",
"attractionName" : "Dali Theatre and Museum",
"attraction" : ObjectId("6210fa7c46bee3fcbd0acc15"),
"provider" : {
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"_id" : ObjectId("6210fa7c46bee3fcbd0acc26")
},
"preview" : "https://app.wegotrip.com/media/CACHE/images/store/001_Ispaniya_Figeras_Teatr-01/783c3a10c34eb40c29f14f704cd9c8d1.jpeg",
"slug" : "the-dali-museum-in-figueres",
"id" : "3",
"key" : "1",
"_id" : ObjectId("6210fa7c46bee3fcbd0acc25")
},
"__v" : 0
}
以上两者都将 detail.duration 设置为 2 并且根据查询，这两个应该被视为交易并在结果文档中找到，但是查询 return s deals: []，一个空数组。我无法找出问题所在。
The $match query syntax is identical to the read operation query syntax; i.e. $match does not accept raw aggregation expressions. To include aggregation expression in $match, use a $expr query expression.
并且需要使用$$获取变量值
To reference variables in pipeline stages, use the "$$" syntax.
将管道中的 $match 阶段更改为：
{
$match: {
_id: {
$ne: "$$id"
},
$expr: {
$eq: [
"$detail.duration",
"$$duration"
]
}
}
}