从MongoDB中的数组中删除对象？
要从MongoDB中的数组中删除对象，可以使用$pull运算符。语法如下：
db.yourCollectionName.update( {'_id':ObjectId("5c6ea036a0c51185aefbd14f")},
{$pull:{"yourArrayName":{"yourArrayFieldName":yourValue}}},
false,true);为了理解上述语法，让我们创建一个带有文档的集合。用于创建包含文档的集合的查询如下：
> db.removeObject.insertOne({"CustomerName":"Maxwell","CustomerAge":23,
... "CustomerDetails":[
... {
... "CustomerId":100,
... "CustomerProduct":"Product-1"
... },
... {
... "CustomerId":150,
... "CustomerProduct":"Product-2"
... },
... {
... "CustomerId":200,
... "CustomerProduct":"Product-3"
... }
... ]
... });
{
"acknowledged" : true,
"insertedId" : ObjectId("5c6ea036a0c51185aefbd14f")
}在find()method的帮助下显示集合中的所有文档。查询如下：
> db.removeObject.find().pretty();
以下是输出：
{
"_id" : ObjectId("5c6ea036a0c51185aefbd14f"),
"CustomerName" : "Maxwell",
"CustomerAge" : 23,
"CustomerDetails" : [
{
"CustomerId" : 100,
"CustomerProduct" : "Product-1"
},
{
"CustomerId" : 150,
"CustomerProduct" : "Product-2"
},
{
"CustomerId" : 200,
"CustomerProduct" : "Product-3"
}
]
}这是从MongoDB中的数组中删除对象的查询：
> db.removeObject.update( {'_id':ObjectId("5c6ea036a0c51185aefbd14f")},
... {$pull:{"CustomerDetails":{"CustomerId":150}}},
... false,true);
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })上面，我们从数组中删除了对象。让我们显示集合中的文档。查询如下：
> db.removeObject.find().pretty();
以下是输出：
{
"_id" : ObjectId("5c6ea036a0c51185aefbd14f"),
"CustomerName" : "Maxwell",
"CustomerAge" : 23,
"CustomerDetails" : [
{
"CustomerId" : 100,
"CustomerProduct" : "Product-1"
},
{
"CustomerId" : 200,
"CustomerProduct" : "Product-3"
}
]
}