我正在查询一个集合并根据一个属性对结果进行排序.有些文档还没有该属性值,即 null.在排序和限制(asc 或 desc)之后,我想在结果末尾保留具有空值的文档.Mongoose 中是否有一种简单的方法可以使用单个查询来做到这一点?如果没有,我如何分别使用两个查询,因为我必须限制结果以及分页?
I am querying a collection and sorting results based on a property. Some documents don't the that property value yet i.e. null. I want to keep the documents with null values at the end of the results after sorting and limiting (asc or desc). Is there a simple way in Mongoose to do that using a single query? If not, how can I use two queries separately since I have to limit the results as well for pagination?
var dealSchema = new Schema({
// For Presentation Purposes Only
dealId: { type: Number, index: true, unique: true },
// BRAND Info
brand: { type: ObjectId, ref: 'brand', index: true },
brandUser: { type: ObjectId, ref: 'user', index: true, required: true },
campaign: { type: ObjectId, ref: 'campaign', index: true },
metrics: {
totalCost: Number,
totalValue: Number,
roi: { type: Number, index: true },
cpe: { type: Number, index: true }
}
})
我想根据metrics.cpe"按升序排序,但希望 null 或 0 值位于列表末尾.示例:
I want to sort based on 'metrics.cpe' in ascending order, but want null or 0 values to be at the end of the list. Example:
[0.1, 0.4, 0.7, 1.5, 2.5, 0, 0, null, null]
示例文档
{
"_id": "590cdf29c102ae31208fa43a",
"campaign": "587e6a880c844c6c2ea01563",
"brand": "5a4cff5f8eaa1c26ca194acc",
"brandUser": "57fd30cf0df04f1100153e07",
"metrics": {
"roi": 0,
"cpe": 0,
"totalValue": 0,
"totalCost": 6000
}
}
我不确定我要说的解决方案.我无法测试这一点,因为我现在没有设置 mongo db,但我认为你可以使用 <collection>.aggregate
以及 $project
和 $sort
来实现这一点.
Am not sure about the solution am about to say. I cant test this out as I dont have a mongo db set right now, but I think that you can use <collection>.aggregate
along with $project
and $sort
to achieve this.
示例代码:
db.inventory.aggregate(
[
{
$project: {
item: 1,
description: { $ifNull: [ "$amount", -1*(<mimimum value>)* ] }
}
},
{
$sort : {
amount : (-1 or 1 depending on the order you want)
}
}
]
)
希望对你有帮助!!
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