这是我的数据库结构
{
"_id" : ObjectId("576155226d1d298c2cc3edca"),
"questionLibrary" : {
"technologyName" : "CSS",
"questions" : [
{
"correctanswer" : {
"A1" : "CSS1"
},
"answeroption" : {
"A4" : "CSS1",
"A3" : "CSS1",
"A2" : "CSS1",
"A1" : "CSS1"
},
"level" : "Amature",
"tags" : "CSS",
"question" : "CSS1"
},
{
"question" : "CSS2",
"tags" : "CSS",
"answeroption" : {
"A1" : "CSS2",
"A2" : "CSS2",
"A3" : "CSS2",
"A4" : "CSS2"
},
"level" : "Amature",
"correctanswer" : {
"A1" : "CSS2"
}
},
{
"correctanswer" : {
"A1" : "CSS3"
},
"answeroption" : {
"A4" : "CSS3",
"A3" : "CSS3",
"A2" : "CSS3",
"A1" : "CSS3"
},
"level" : "Amature",
"tags" : "CSS",
"question" : "CSS3"
},
{
"correctanswer" : {
"A1" : "CSS4"
},
"answeroption" : {
"A4" : "CSS4",
"A3" : "CSS4",
"A2" : "CSS4",
"A1" : "CSS4"
},
"level" : "Amature",
"tags" : "CSS",
"question" : "CSS4"
},
{
"correctanswer" : {
"A1" : "CSS5"
},
"answeroption" : {
"A4" : "CSS5",
"A3" : "CSS5",
"A2" : "CSS5",
"A1" : "CSS5"
},
"level" : "Amature",
"tags" : "CSS",
"question" : "CSS5"
},
{
"correctanswer" : {
"A1" : "CSS6"
},
"answeroption" : {
"A4" : "CSS6",
"A3" : "CSS6",
"A2" : "CSS6",
"A1" : "CSS6"
},
"level" : "Amature",
"tags" : "CSS",
"question" : "CSS6"
},
{
"correctanswer" : {
"A1" : "CSS7"
},
"answeroption" : {
"A4" : "CSS7",
"A3" : "CSS7",
"A2" : "CSS7",
"A1" : "CSS7"
},
"level" : "Amature",
"tags" : "CSS",
"question" : "CSS7"
},
{
"correctanswer" : {
"A1" : "CSS8"
},
"answeroption" : {
"A4" : "CSS8",
"A3" : "CSS8",
"A2" : "CSS8",
"A1" : "CSS8"
},
"level" : "Amature",
"tags" : "CSS",
"question" : "CSS8"
},
{
"correctanswer" : {
"A1" : "CSS9"
},
"answeroption" : {
"A4" : "CSS9",
"A3" : "CSS9",
"A2" : "CSS9",
"A1" : "CSS9"
},
"level" : "Amature",
"tags" : "CSS",
"question" : "CSS9"
},
{
"correctanswer" : {
"A1" : "CSS10"
},
"answeroption" : {
"A4" : "CSS10",
"A3" : "CSS10",
"A2" : "CSS10",
"A1" : "CSS10"
},
"level" : "Amature",
"tags" : "CSS",
"question" : "CSS10"
}
]
},
"__v" : 3
}
每次触发查询时，我都想从问题数组中获取一个随机对象(随机问题)。
我不想一次收集所有对象并在 Node 中操作它们。是否可以编写一个查询，以便每次都返回一个随机对象？
最佳答案
试试这个逻辑
1) 使用 $unwind在数组 "questions"上，如果使用 includeArrayIndex，它将创建带有索引的文档，请参见 examples在展开文档中
2) 展开数组后，传递一个随机数来检索问题
关于node.js - 从MongoDB中的数组中获取随机元素，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37853003/