切片与投影与C＃ [英] Slice with Projection with C#

问题描述

有没有什么方法使用c＃驱动程序在一个查询中实现切片和投影？
下面是我想用c＃实现的，但是我坚持，任何人都可以帮助我吗？

Is there any way to implement a slice along with a projection in just one query using the c# driver? Below is what i am trying to achieve using c#, but im stuck, can anyone help me out wit it?

db.employee.find({"employeeId": "999"}, { "empActivity" : { "$slice": -1 } }, {"employeeId": 1, "empActivity.transId": 1, _id: 0})

注意：empActivity是一个包含嵌套文档的数组，

Note : empActivity is a an array containing nested documents, my query above works perfectly via the mongo shell but i am not able to figure out its equivalent in C#.

推荐答案

有一种方法可以做到这一点与C＃驱动程序。方法可以在构建器上进行，因此所有 .Slice（）和 .Include（）和 .Exclude（）

There is a way to do this with the C# driver. Methods can be chanined on builders, so all of .Slice() and .Include()and .Exclude()

var fields = Fields.Slice("empActivity", -1)
    .Include("employeeId", "empActivity.transId")
    .Exclude("_id");

var cursor = collection.Find(query).SetFields(fields); 

这篇关于切片与投影与C＃的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！