用mongoose/mongoDB查询嵌套文档
用mongoose/mongoDB查询嵌套文档
提问于 2015-01-20 21:17:46
我有一个汽车模型，如下所示
{
"_id": "54b8a71843286774060b8bed",
"name": "Car1",
"active": true,
"model": [
{
"name": "Model1",
"active": true,
"_id": "54b8a71843286774060b8bee",
"available": [
{
"Day": "Mon",
"quantity": "6"
},
{
"Day": "Tue",
"quantity": "6"
},
{
"Day": "Wed",
"quantity": "6"
},
{
"Day": "Thurs",
"quantity": "6"
},
{
"Day": "Fri",
"quantity": "0"
}
]
},
{
"name": "Model2",
"active": true,
"_id": "54b8a71843286774060b8bef",
"available": [
{
"Day": "Mon",
"quantity": "6"
},
{
"Day": "Tue",
"quantity": "6"
},
{
"Day": "Wed",
"quantity": "6"
},
{
"Day": "Thurs",
"quantity": "6"
},
{
"Day": "Fri",
"quantity": "6"
}
]
},
{
"name": "Model3",
"active": true,
"_id": "54b8a71843286774060b8beg",
"available": [
{
"Day": "Mon",
"quantity": "6"
},
{
"Day": "Tue",
"quantity": "6"
},
{
"Day": "Wed",
"quantity": "6"
},
{
"Day": "Thurs",
"quantity": "6"
},
{
"Day": "Fri",
"quantity": "0"
}
]
}
]
}
我正在尝试搜索汽车在给定日期的可用性。例如，如果我选择星期五，那么它应该在星期五返回数量超过0的汽车，但目前它也返回数量为0的所有汽车。
我已经写了如下的问题
Car.find({ 'active'：真，'model.available'：{ $elemMatch：{$gte : 1 } )
但它也会返回数量为0的文档。
回答 1
Stack Overflow用户
发布于 2015-01-20 22:34:18
为此，您需要aggregation pipeline。
下面的代码片段实现了这一点：
- 查找至少具有一个匹配模型的所有文档。
- 拆分文档:其中包含3个模型数组的文档将转换为三个文档，每个文档具有一个模型：
{name: "Car1": 1, models: [{name: "Model1"}, {name: "Model2"}, {name: "Model3"}]}
变成：
对拆分的文档(再次)按数量进行筛选，然后day.
- Optionally，将文档重新粘合在一起。
{name: "Car1", models: {name: "Model1"}}&{name: "Car1", models: {name: "Model2"}}&{name: "Car1", models: {name: "Model2"}}拆分文档。你可能不需要在你的application.
中使用它
db.cars.aggregate([
// First, we do your query, which will return
// every document that has _at least one_
// model that is available.
{$match: {
'active': true,
'model.available': {$elemMatch: {
'quantity': {$gte: 1},
'Day': 'Fri'
}}
}},
// We split up the found documents,
// every document will now have exactly
// one 'model' in it.
{$unwind: "$model"},
// We now filter the split documents.
{$match: {
'model.available': {$elemMatch: {
'quantity': {$gte: 1},
'Day': 'Fri'
}}
}},
// If you want, you can now glue the
// models back together again.
{$group: {
_id: "$_id", // Group all documents with the same _id
name: {$first: "$name"},
active: {$first: "$active"},
model: {$push: "$model"} // Make an array of models
}}
])重要提示：要使$gte正常工作，您需要将数量存储为数字，而不是字符串。由于您的示例将数字存储为字符串，因此您可能需要在数据库中仔细检查它们。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/28046335
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