是否可以强制转换MongoDB查询？
是的，可以强制转换MongoDB查询-
db.yourCollectionName.find("this.yourFieldName >yourValue);为了理解这个概念，让我们用文档创建一个集合。使用文档创建集合的查询如下-
> db.castingDemo.insertOne({"Amount":"200"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c947e874cf1f7a64fa4df42")
}
> db.castingDemo.insertOne({"Amount":"100"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c947e8e4cf1f7a64fa4df43")
}
> db.castingDemo.insertOne({"Amount":"110"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c947e944cf1f7a64fa4df44")
}
> db.castingDemo.insertOne({"Amount":"95"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c947e9d4cf1f7a64fa4df45")
}
> db.castingDemo.insertOne({"Amount":"85"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c947ea44cf1f7a64fa4df46")
}
> db.castingDemo.insertOne({"Amount":"75"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c947ebd4cf1f7a64fa4df47")
}在find()method的帮助下显示集合中的所有文档。查询如下-
> db.castingDemo.find().pretty();
以下是输出-
{ "_id" : ObjectId("5c947e874cf1f7a64fa4df42"), "Amount" : "200" }
{ "_id" : ObjectId("5c947e8e4cf1f7a64fa4df43"), "Amount" : "100" }
{ "_id" : ObjectId("5c947e944cf1f7a64fa4df44"), "Amount" : "110" }
{ "_id" : ObjectId("5c947e9d4cf1f7a64fa4df45"), "Amount" : "95" }
{ "_id" : ObjectId("5c947ea44cf1f7a64fa4df46"), "Amount" : "85" }
{ "_id" : ObjectId("5c947ebd4cf1f7a64fa4df47"), "Amount" : "75" }这是自动从字符串转换为数字的查询-
> db.castingDemo.find("this.Amount > 85");以下是输出-
{ "_id" : ObjectId("5c947e874cf1f7a64fa4df42"), "Amount" : "200" }
{ "_id" : ObjectId("5c947e8e4cf1f7a64fa4df43"), "Amount" : "100" }
{ "_id" : ObjectId("5c947e944cf1f7a64fa4df44"), "Amount" : "110" }
{ "_id" : ObjectId("5c947e9d4cf1f7a64fa4df45"), "Amount" : "95" }