如何在MongoDB中的子文档数组中添加子文档？
使用$push运算符添加子文档。首先让我们创建一个包含文档的集合-
> db.subDocumentToSubDocumentDemo.insertOne(
{
"_id" :101,
"StudentName" : "Larry",
"StudentAge" : 21,
"StudentDetails" : [
{
"StudentCountryName" : "US",
"StudentFavouriteSubjectList" : [ ]
}
]
}
);
{ "acknowledged" : true, "insertedId" : 101 }以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.subDocumentToSubDocumentDemo.find().pretty();
这将产生以下输出-
{
"_id" : 101,
"StudentName" : "Larry",
"StudentAge" : 21,
"StudentDetails" : [
{
"StudentCountryName" : "US",
"StudentFavouriteSubjectList" : [ ]
}
]
}以下是将子文档添加到MongoDB中的子文档数组的查询-
> db.subDocumentToSubDocumentDemo.update(
{ "_id": 101 },
{
"$push": {
"StudentDetails": {
"StudentCountryName" : "UK",
"StudentFavouriteSubjectList" : ["MongoDB","Java" ]
}
}
}
);
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })让我们再次检查所有文件-
> db.subDocumentToSubDocumentDemo.find().pretty();
这将产生以下输出-
{
"_id" : 101,
"StudentName" : "Larry",
"StudentAge" : 21,
"StudentDetails" : [
{
"StudentCountryName" : "US",
"StudentFavouriteSubjectList" : [ ]
},
{
"StudentCountryName" : "UK",
"StudentFavouriteSubjectList" : [
"MongoDB",
"Java"
]
}
]
}