i am trying to do some queries to my db... but i am new in mongodb and i dont know what operator i have to use, or maybe i just do not know how to do it.
i have a collection like this.
const userSchema= new Schema({
user: { type: String },
object: { type: String }
})
then i receive in my server a query like this
{
users: ['John', 'Michael', 'Peter'],
objects: ['Object1','Object2','Object3','Object4', 'Object5']
}
so.. in my controller i do this to find...
userModel.find({ user: { $in: req.body.users}, object: { $in: req.body.objects})
.then((users)=>{
res.json(users)
})
Ok, this is working... but, in the case that one of the arrays Users or Objects is empty, it doesn't find nothing... so, how i can handle it? there is any operator that can find all if the array is empty or something?
for example.. if the query comes like this.
{
users: ['John', 'Michael', 'Peter'],
objects: []
}
i would like to find the users in my Users array even if i dont receive any object.
Any help? thank you in advance
You have to create custom match criteria
const query = {
fieldName: { $gte: ..., $lte: ... }
}
if (req.body.users.length > 0) {
query.users = req.body.users
}
if (req.body.objects.length > 0) {
query.objects = req.body.objects
}
userModel.find(query).then((users) => {
console.log(users)
})
Related
I have a database like this:
[
{
"universe":"comics",
"saga":[
{
"name":"x-men",
"characters":[
{
"character":"wolverine",
"picture":"618035022351.png"
},
{
"character":"cyclops",
"picture":"618035022352.png"
}
]
}
]
},
{
"universe":"dc",
"saga":[
{
"name":"spiderman",
"characters":[
{
"character":"venom",
"picture":"618035022353.png"
}
]
}
]
}
]
and with this code I manage to update one of the objects in my array. specifically the object where character: wolverine
db.mydb.findOneAndUpdate({
"universe": "comics",
"saga.name": "x-men",
"saga.characters.character": "wolverine"
}, {
$set: {
"saga.$[].characters.$[].character": "lobezno",
"saga.$[].characters.$[].picture": "618035022354.png",
}
}, {
new: false
}
)
it returns all my document, I need ONLY the document matched
I would like to return the object that I have updated without having to make more queries to the database.
Note
I have been told that my code does not work well as it should, apparently my query to update this bad, I would like to know how to fix it and get the object that matches these search criteria.
In other words how can I get this output:
{
"character":"wolverine",
"picture":"618035022351.png"
}
in a single query using filters
{
"universe": "comics",
"saga.name": "x-men",
"saga.characters.character": "wolverine"
}
My MongoDB knowledge prevents me from correcting this.
Use the shell method findAndModify to suit your needs.
But you cannot use the positional character $ more than once while projecting in MongoDb, so you may have to keep track of it yourself at client-side.
Use arrayFilters to update deeply nested sub-document, instead of positional all operator $[].
Below is a working query -
var query = {
universe: 'comics'
};
var update = {
$set: {
'saga.$[outer].characters.$[inner].character': 'lobezno',
'saga.$[outer].characters.$[inner].picture': '618035022354.png',
}
};
var fields = {
'saga.characters': 1
};
var updateFilter = {
arrayFilters: [
{
'outer.name': 'x-men'
},
{
'inner.character': 'wolverine'
}
]
};
db.collection.findAndModify({
query,
update,
fields,
arrayFilters: updateFilter.arrayFilters
new: true
});
If I understand your question correctly, your updating is working as expected and your issue is that it returns the whole document and you don't want to query the database to just to return these two fields.
Why don't you just extract the fields from the document returned from your update? You are not going to the database when doing that.
var extractElementFromResult = null;
if(result != null) {
extractElementFromResult = result.saga
.filter(item => item.name == "x-men")[0]
.characters
.filter(item => item.character == "wolverine")[0];
}
I have a situation where a model changed at some point in time and I am faced with (for argument sake) half my data liks like this
{
_id: OID,
things: [{
_id:OID,
arm: string,
body: string
}],
other: string
}
and the other half of my data look like this
{
_id: OID,
things: [{
_id:OID,
upper_appendage: string,
body: string
}],
other: string
}
I would like to 'correct' half of the data - so that I DON'T have to accommodate both names for 'arm' in my application code.
I have tried a couple different things:
The first errors
db.getCollection('x')
.find({things:{$exists:true}})
.forEach(function (record) {
record.things.arm = record.things.upper_appendage;
db.users.save(record);
});
and this - which destroys all the other data in
db.getCollection('x')
.find({things:{$exists:true}})
.forEach(function (record) {
record.things = {
upper_appendage.arm = record.things.upper_appendage
};
db.users.save(record);
});
Keeping in mind that there is other data I want to maintain...
How can I do this???
the $rename operator should have worked for this job but unfortunately it doesn't seem to support nested array fields (as of mongodb server 4.2). instead you'd need a forEach like the following:
db.items.find({
things: {
$elemMatch: {
arm: {
$exists: true
}
}
}
}).forEach(function(item) {
for (i = 0; i != item.things.length; ++i)
{
item.things[i].upper_appendage = item.things[i].arm;
delete item.things[i].arm; ;
}
db.items.update({
_id: item._id
}, item);
})
note: i've assumed you want to make all records have upper_appendageand get rid of 'arm' field. if it's the other way you want, just switch things around.
I have Mongoose schema like this:
{
......
project: [
{
Name: String,
Criteria:[
{
criteriaName:String,
}
]
}
]
......
}
And I want to remove one of the objects of criteria array which is in the array of project based on the object id
I tried the code following
criteria.findOneAndUpdate({
"_id": uid,
},{ $pull: { "project.Criteria": { _id: cid } } }, (err) => {
......
}
However this cannot work, it said "Cannot use the part (Criteria) of (project.Criteria) to traverse the element"
Do you need to do it in one query to the database? If not, the following solution may work for you:
criteria.findOne({ _id: uid })
.then((obj) => {
// Filter out the criteria you wanted to remove
obj.project.Criteria = obj.project.Criteria.filter(c => c._id !== cid);
// Save the updated object to the database
return obj.save();
})
.then((updatedObj) => {
// This is the updated object
})
.catch((err) => {
// Handle error
});
Sorry if the .then/.catch is confusing. I can rewrite with callbacks if necessary, but I think this looks a lot cleaner. Hope this helps!
I'm trying to project out only the matched element of an array, in the updated version. But I'm getting the error: "MongoError: >1 field in obj: { _id: 0, lotes.$: 1 }"
If I remove 'new: true', it works. But then I have the doc before the update. And I would really like the updated version.
What's wrong? How can I fix it?
The Offer doc is something like:
{
_id
series: [ Serie ]
}
Serie structure is something like:
{
_id
public.available: Number
public.expDate: Date
}
I'm using Mongoose:
var query = {
'_id': offerId,
'series': {
$elemMatch: {
'_id': serieId,
'public.available': {$gt:0},
'public.expDate': {$gt: now}
}
}
};
var update = {
$inc: { 'series.$.public.available' : -1 }
};
var options = { // project out just the element found, updated
new:true,
select: {
'_id': 0,
'series.$': 1
}
};
Offers.findOneAndUpdate(query, update, options)
.then( element => {
...
}
For anyone else experiencing this error, it is also the most common error when trying to perform an illegal action such as trying to update a database element inside of a findOne request.
Making sure your request is correct, such as findOneAndUpdate should be your first port of call when you get this error.
As Anthony Winzlet pointed out in the links, there seems to be an issue with Mongoose, in which if you use 'new:true', you can't project out the $elemMatch.
So my solution was to keep using 'new:true' only, without projections. And reduce the array later on to get the $elemMatch:
.then( (result) => {
var aux = result.series.reduce((acu, serie, index) => {
if (serie._id == req.params.serieId) return index;
});
var element = result.series[aux];
}
I'm trying to update a sub document on an existing collection. I'm getting a MongoDB error message.
"MongoError: The positional operator did not find the match needed from the query. Unexpanded update: articleWords.$ [409]"
From my Articles Simple Schema
"articleWords.$": {
type: Object
},
"articleWords.$.wordId": {
type: String,
label: 'Word ID'
},
"articleWords.$.word": {
type: String,
label: 'Word'
},
Update Function
function updateArticle(_id,wordArr) {
_.each(wordArr,function(elem) {
var ret = Articles.update(
{'_id': _id},
{ $set: { 'articleWords.$': { 'wordId': elem.wordId, 'word': elem.word } }
});
});
return true;
}
As you can see I am passing an array of objects. Is there a better way to do this than _.each ?
CLARIFICATION
Thank you to #corvid for the answer. I think I didn't make my question clear enough. There does exist an article record, but there is no data added to the articleWords attribute. Essentially we are updating a record but insert into the articleWords array.
A second attempt, is also not working
_.each(wordArr,function(elem) {
var ret = Articles.update(
{'_id': _id},
{ $set: { 'articleWords.$.wordId': elem.wordId, 'articleWords.$.word': elem.word } }
);
});
Yes, you need your selector to match something within the subdocument. For example,
Articles.update({
'_id': <someid>,
'words.wordId': <somewordid>
}, {
$set: {
'words.$.word': elem.word,
'words.$.wordId': elem.wordId
}
});
If the array doesn't exist yet then you're going about this in the hardest way possible. You can just set the entire array at one go:
var ret = Articles.update(
{'_id': _id},
{ $set: { articleWords: wordArr }}
);
I can see that wordArr already has the id and string. This will work as long as it doesn't have more content. If it does then you can just make a second version with the parts you want to keep.