使用find()在MongoDB中搜索嵌套键？
要find()在MongoDB中搜索嵌套键，可以使用点（。）表示法。以下是语法
db.yourCollectionName.find({"yourOuterFieldName.yourInnerFieldName":"yourValue"}).pretty();让我们首先创建一个包含文档的集合：
>db.searchForNestedKeysDemo.insertOne({"ClientName":"Larry","ClientAge":28,"ClientExtra
Details":{"isEducated":true,"CountryName":"US"}});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ca20e8b66324ffac2a7dc64")
}
>db.searchForNestedKeysDemo.insertOne({"ClientName":"Chris","ClientAge":29,"ClientExtra
Details":{"isEducated":false,"CountryName":"UK"}});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ca20ea366324ffac2a7dc65")
}
>db.searchForNestedKeysDemo.insertOne({"ClientName":"David","ClientAge":39,"ClientExtra
Details":{"isEducated":true,"CountryName":"AUS"}});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ca20eba66324ffac2a7dc66")
}以下是在find()方法的帮助下显示集合中所有文档的查询
> db.searchForNestedKeysDemo.find().pretty();
这将产生以下输出
{
"_id" : ObjectId("5ca20e8b66324ffac2a7dc64"),
"ClientName" : "Larry",
"ClientAge" : 28,
"ClientExtraDetails" : {
"isEducated" : true,
"CountryName" : "US"
}
}
{
"_id" : ObjectId("5ca20ea366324ffac2a7dc65"),
"ClientName" : "Chris",
"ClientAge" : 29,
"ClientExtraDetails" : {
"isEducated" : false,
"CountryName" : "UK"
}
}
{
"_id" : ObjectId("5ca20eba66324ffac2a7dc66"),
"ClientName" : "David",
"ClientAge" : 39,
"ClientExtraDetails" : {
"isEducated" : true,
"CountryName" : "AUS"
}
}以下是在MongoDB中搜索嵌套键的查询
> db.searchForNestedKeysDemo.find({"ClientExtraDetails.CountryName":"UK"}).pretty();这将产生以下输出
{
"_id" : ObjectId("5ca20ea366324ffac2a7dc65"),
"ClientName" : "Chris",
"ClientAge" : 29,
"ClientExtraDetails" : {
"isEducated" : false,
"CountryName" : "UK"
}
}