MongoDB的更新查询基于所述值未设置特定阵列成员
问题描述：
我有子文档的阵列像下面MongoDB的更新查询基于所述值未设置特定阵列成员
/* record 1 */
{
"_id" : "462044",
"program" : [
{
"name" : "Business Services"
},
{
"name" : "Homeland Security"
},
{
"title" : [
"associate"
],
"name" : "Engineering"
},
{
"title" : [
"associate"
],
"name" : "Computer Software"
}
]
}
/* record 2 */
{
"_id" : "462045",
"program" : [
{
"name" : "Business Services"
},
{
"name" : "Homeland Security"
},
{
"title" : [
"associate"
],
"name" : "Engineering"
},
{
"title" : [
"associate"
],
"name" : "Computer Software"
}
]
}
[我想删除不具有“标题”的子构件阵列成员]
我怎么能写蒙戈更新查询或函数的NodeJS得到以下文件集
/* record 1 */
{
"_id" : "462044",
"program" : [
{
"title" : [
"associate"
],
"name" : "Engineering"
},
{
"title" : [
"associate"
],
"name" : "Computer Software"
}
]
}
/* record 2 */
{
"_id" : "462045",
"program [
{
"title" : [
"associate"
],
"name" : "Engineering"
},
{
"title" : [
"associate"
],
"name" : "Computer Software"
}
]
}
答
那么，首先所有的文档结构看起来很奇怪。每个记录都有一个不同的字段，表示基本上相同的信息，在您的案例中school1和school2。
如果您将这些字段重命名为school，可以轻松修复。
如果您修复了文档结构，您可以借助聚合框架和普通更新查询轻松地删除所需的子文档。
例子：
db.collection.aggregate([
{
$project: {
school: {
$filter: {
input: "$school.program",
as: "prog",
cond: {
$ne: [
{
$ifNull: [
"$$prog.title",
true
]
},
true
]
}
}
}
}
}
]).forEach(function(o){
db.collection.updateOne({
_id: o._id
},
{
$set: {
school: o.school
}
});
})
这将会把你的旧文件（删除所有的子域形成不包含title程序：
{
"_id" : ObjectId("57371cdf81e9959ba1a5fab0"),
"school" : [
{
"title" : [
"associate"
],
"name" : "Engineering"
},
{
"title" : [
"associate"
],
"name" : "Computer Software"
}
]
}
{
"_id" : ObjectId("57371cdf81e9959ba1a5fab1"),
"school" : [
{
"title" : [
"associate"
],
"name" : "Engineering"
},
{
"title" : [
"associate"
],
"name" : "Computer Software"
}
]
}