如何使用 MongoDB db.coll.find() 根据内部类中的字段进行搜索?
mongodbdatabasebig data analytics
使用点符号 (.) 在 MongoDB 内部类中进行搜索。首先，我们创建一个包含文档的集合。 −
> db.searchInInnerDemo.insertOne(
... {
... "StudentFirstName" : "Robert",
... "StudentTechnicalDetails":
... {
... "StudentBackEndTechnology" : "MongoDB",
... "StudentLanguage" : "Java"
... }
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd2dd89b64f4b851c3a13d2")
}
>
> db.searchInInnerDemo.insertOne(
... {
... "StudentFirstName" : "David",
... "StudentTechnicalDetails":
... {
... "StudentBackEndTechnology" : "MySQL",
... "StudentLanguage" : "PHP"
... }
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd2dda3b64f4b851c3a13d3")
}
以下是使用 find() 方法显示集合中的所有文档的查询 −
> db.searchInInnerDemo.find().pretty();
这将产生以下输出 −
{
"_id" : ObjectId("5cd2dd89b64f4b851c3a13d2"),
"StudentFirstName" : "Robert",
"StudentTechnicalDetails" : {
"StudentBackEndTechnology" : "MongoDB",
"StudentLanguage" : "Java"
}
}
{
"_id" : ObjectId("5cd2dda3b64f4b851c3a13d3"),
"StudentFirstName" : "David",
"StudentTechnicalDetails" : {
"StudentBackEndTechnology" : "MySQL",
"StudentLanguage" : "PHP"
}
}
案例 1 − 在内部类中搜索以仅匹配一个属性的查询 −
>db.searchInInnerDemo.find({"StudentTechnicalDetails.StudentBackEndTechnology":"MongoDB"}).pretty();
这将产生以下输出 −
{
"_id" : ObjectId("5cd2dd89b64f4b851c3a13d2"),
"StudentFirstName" : "Robert",
"StudentTechnicalDetails" : {
"StudentBackEndTechnology" : "MongoDB",
"StudentLanguage" : "Java"
}
}
案例 2 − 查询使用扫描完整字段名称搜索文档 −
>db.searchInInnerDemo.find({"StudentTechnicalDetails":{"StudentBackEndTechnology":"MongoDB","StudentLanguage":"Java"}}).pretty();
这将产生以下输出 −
{
"_id" : ObjectId("5cd2dd89b64f4b851c3a13d2"),
"StudentFirstName" : "Robert",
"StudentTechnicalDetails" : {
"StudentBackEndTechnology" : "MongoDB",
"StudentLanguage" : "Java"
}
}
