[英]add item to array if it doesn't exist mongodb
I'm running a simple application with mongoDB
+ nodejs
, I'm trying to achieve the following:我正在使用
mongoDB
+ nodejs
运行一个简单的应用程序,我正在尝试实现以下目标:
The unit belongs to a company , the classroom belongs to a unit and the user belongs to a classroom .单位属于公司,教室属于单位,用户属于教室。
In certain moment, I want to add the user to another unit or/and classroom, then he'll belong to 2 or more units/classrooms.在某个时刻,我想将用户添加到另一个单元或/和教室,然后他将属于 2 个或更多单元/教室。
My form will sent only one unit/classroom per time, in this case, I want to add it to the user model unit:[string]
and classroom:[string]
only if he doesn't previously belong to it.我的表格每次只发送一个单元/教室,在这种情况下,我想将其添加到用户 model
unit:[string]
和classroom:[string]
],前提是他以前不属于它。 So I need to check if the arrays already have the sent data, if don't, add to it.所以我需要检查arrays是否已经有发送的数据,如果没有,添加它。
Mongo has the $addToSet
property, and the $ne
to do it, but I can't seem to make it work. Mongo 有
$addToSet
属性和$ne
来做这件事,但我似乎无法让它工作。
Here's my code:这是我的代码:
User.findById(req.body._id)
.select("-__v")
.exec((err: Error, user: any) => {
if (err) {
// display error
}
if (!user) {
// display error
}
user.update({
unit: {
$ne: user.unit
},
classroom: {
$ne: user.classroom
}
}, {
$addToSet: {
unit: req.body.unit,
classroom: req.body.classroom
}
}).exec((err: Error) => {
if (err) {
// Display error
}
res.status(200).json({
status: "OK",
response: response,
})
return
})
It belongs to "Academy one" and the classroom id reference, I will add him to another unit like "Academy 2" and add another classroom reference, but if I add him to another classroom of "Academy One", I don't want a duplicate item in it's unit array.它属于“Academy one”和classic id reference,我会将他添加到“Academy 2”这样的另一个单元并添加另一个教室引用,但是如果我将他添加到“Academy One”的另一个教室,我不想要其单位数组中的重复项。
When I post the following through postman
, it gives me the error:当我通过
postman
发布以下内容时,它给了我错误:
{
"_id":"5d8ba151248ecb4df8803657", // user id
"unit":"Test", // another unit
"classroom":"5d8a709f44f55e4a785e2c50" // another classroom
}
Response:回复:
{ "status": "NOK", "response": "Cast to [string] failed for value \"[{\"$ne\":[\"Academy One\"]}]\" at path \"unit\"" }
{ "status": "NOK", "response": "Cast to [string] failed for value \"[{\"$ne\":[\"Academy One\"]}]\" at path \"unit \"" }
What am I missing?我错过了什么?
Actually, I didn't needed the $ne
operator, I just needed to use the $addToSet
directly实际上,我不需要
$ne
运算符,我只需要直接使用$addToSet
user.updateOne({
$addToSet: { unit: req.body.unit, classroom: req.body.classroom }
}).exec((err: Error) => {
Thanks!谢谢!
You need to use $nin
instead of $ne
, https://docs.mongodb.com/manual/reference/operator/query/nin/您需要使用
$nin
而不是$ne
, https://docs.mongodb.com/manual/reference/operator/query/nin/
unit: {$nin: [user.unit]}
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