While building an API, I need to match documents that contain pending or active values for the key status.
When trying
args.status = {
$or: [
'active',
'pending'
]
}
I get an error: cannot use $or with string
However,
args.status = {
$in: [
'active',
'pending'
]
}
works just fine.
I would expect $or to work here. Can someone provide context on the differences between the two and why Strings require $in?
$or performs the logical OR operation on an ARRAY with more than two expressions e.g. {$or:[{name:"a"},{name:"b"}]} This query will return the record which are having either name 'a' or 'b'.
$in works on the array and return the documents which are which contains any of the field from your specified array e.g.{name:{$in:['a','b']}} This query will return the documents where name is either 'a' or 'b'.
Ideally both are doing same but just having the syntax difference.
In your case you have to modify your OR query syntax and add the condition expessions in an ARRAY.
{ $or: [
{
"args.status": "active"
},
{
"args.status": "pending"
}
]
}
Thats because $or expects array of objects. Objects that defines some filters out of which at least one needs to be match to return the result. For your particular scenario $in is the best option. Still if you wanna go with $or, the query will be like:
{
$or: [
{'args.status' : {$eq: 'active'}},
{'args.status' : {$eq: 'pending'}}
]
}
I'd suggest you stick with $in as it is the best fit for your requirement.
You can check the official docs for more details on $or
Hope this helps :)
Related
I am trying to update a value in the nested array but can't get it to work.
My object is like this
{
"_id": {
"$oid": "1"
},
"array1": [
{
"_id": "12",
"array2": [
{
"_id": "123",
"answeredBy": [], // need to push "success"
},
{
"_id": "124",
"answeredBy": [],
}
],
}
]
}
I need to push a value to "answeredBy" array.
In the below example, I tried pushing "success" string to the "answeredBy" array of the "123 _id" object but it does not work.
callback = function(err,value){
if(err){
res.send(err);
}else{
res.send(value);
}
};
conditions = {
"_id": 1,
"array1._id": 12,
"array2._id": 123
};
updates = {
$push: {
"array2.$.answeredBy": "success"
}
};
options = {
upsert: true
};
Model.update(conditions, updates, options, callback);
I found this link, but its answer only says I should use object like structure instead of array's. This cannot be applied in my situation. I really need my object to be nested in arrays
It would be great if you can help me out here. I've been spending hours to figure this out.
Thank you in advance!
General Scope and Explanation
There are a few things wrong with what you are doing here. Firstly your query conditions. You are referring to several _id values where you should not need to, and at least one of which is not on the top level.
In order to get into a "nested" value and also presuming that _id value is unique and would not appear in any other document, you query form should be like this:
Model.update(
{ "array1.array2._id": "123" },
{ "$push": { "array1.0.array2.$.answeredBy": "success" } },
function(err,numAffected) {
// something with the result in here
}
);
Now that would actually work, but really it is only a fluke that it does as there are very good reasons why it should not work for you.
The important reading is in the official documentation for the positional $ operator under the subject of "Nested Arrays". What this says is:
The positional $ operator cannot be used for queries which traverse more than one array, such as queries that traverse arrays nested within other arrays, because the replacement for the $ placeholder is a single value
Specifically what that means is the element that will be matched and returned in the positional placeholder is the value of the index from the first matching array. This means in your case the matching index on the "top" level array.
So if you look at the query notation as shown, we have "hardcoded" the first ( or 0 index ) position in the top level array, and it just so happens that the matching element within "array2" is also the zero index entry.
To demonstrate this you can change the matching _id value to "124" and the result will $push an new entry onto the element with _id "123" as they are both in the zero index entry of "array1" and that is the value returned to the placeholder.
So that is the general problem with nesting arrays. You could remove one of the levels and you would still be able to $push to the correct element in your "top" array, but there would still be multiple levels.
Try to avoid nesting arrays as you will run into update problems as is shown.
The general case is to "flatten" the things you "think" are "levels" and actually make theses "attributes" on the final detail items. For example, the "flattened" form of the structure in the question should be something like:
{
"answers": [
{ "by": "success", "type2": "123", "type1": "12" }
]
}
Or even when accepting the inner array is $push only, and never updated:
{
"array": [
{ "type1": "12", "type2": "123", "answeredBy": ["success"] },
{ "type1": "12", "type2": "124", "answeredBy": [] }
]
}
Which both lend themselves to atomic updates within the scope of the positional $ operator
MongoDB 3.6 and Above
From MongoDB 3.6 there are new features available to work with nested arrays. This uses the positional filtered $[<identifier>] syntax in order to match the specific elements and apply different conditions through arrayFilters in the update statement:
Model.update(
{
"_id": 1,
"array1": {
"$elemMatch": {
"_id": "12","array2._id": "123"
}
}
},
{
"$push": { "array1.$[outer].array2.$[inner].answeredBy": "success" }
},
{
"arrayFilters": [{ "outer._id": "12" },{ "inner._id": "123" }]
}
)
The "arrayFilters" as passed to the options for .update() or even
.updateOne(), .updateMany(), .findOneAndUpdate() or .bulkWrite() method specifies the conditions to match on the identifier given in the update statement. Any elements that match the condition given will be updated.
Because the structure is "nested", we actually use "multiple filters" as is specified with an "array" of filter definitions as shown. The marked "identifier" is used in matching against the positional filtered $[<identifier>] syntax actually used in the update block of the statement. In this case inner and outer are the identifiers used for each condition as specified with the nested chain.
This new expansion makes the update of nested array content possible, but it does not really help with the practicality of "querying" such data, so the same caveats apply as explained earlier.
You typically really "mean" to express as "attributes", even if your brain initially thinks "nesting", it's just usually a reaction to how you believe the "previous relational parts" come together. In reality you really need more denormalization.
Also see How to Update Multiple Array Elements in mongodb, since these new update operators actually match and update "multiple array elements" rather than just the first, which has been the previous action of positional updates.
NOTE Somewhat ironically, since this is specified in the "options" argument for .update() and like methods, the syntax is generally compatible with all recent release driver versions.
However this is not true of the mongo shell, since the way the method is implemented there ( "ironically for backward compatibility" ) the arrayFilters argument is not recognized and removed by an internal method that parses the options in order to deliver "backward compatibility" with prior MongoDB server versions and a "legacy" .update() API call syntax.
So if you want to use the command in the mongo shell or other "shell based" products ( notably Robo 3T ) you need a latest version from either the development branch or production release as of 3.6 or greater.
See also positional all $[] which also updates "multiple array elements" but without applying to specified conditions and applies to all elements in the array where that is the desired action.
I know this is a very old question, but I just struggled with this problem myself, and found, what I believe to be, a better answer.
A way to solve this problem is to use Sub-Documents. This is done by nesting schemas within your schemas
MainSchema = new mongoose.Schema({
array1: [Array1Schema]
})
Array1Schema = new mongoose.Schema({
array2: [Array2Schema]
})
Array2Schema = new mongoose.Schema({
answeredBy": [...]
})
This way the object will look like the one you show, but now each array are filled with sub-documents. This makes it possible to dot your way into the sub-document you want. Instead of using a .update you then use a .find or .findOne to get the document you want to update.
Main.findOne((
{
_id: 1
}
)
.exec(
function(err, result){
result.array1.id(12).array2.id(123).answeredBy.push('success')
result.save(function(err){
console.log(result)
});
}
)
Haven't used the .push() function this way myself, so the syntax might not be right, but I have used both .set() and .remove(), and both works perfectly fine.
I'm having issues with mongoose queries.
I am trying to check if a object with an Id is in an array of objects.
So my query is like
db.getCollection('adunits').find(
{_id: ObjectId("5bd9bc1ca4efae39d0b5a58e")},
{$in : ["5bf510156c154934150ef006","5bf5309e6c154934150f00a6","5bd9b874a4efae39d0b5a58d","5bf52a876c154934150efe4a"]}
)
As you can see, my ObjectId("5bd9...") IS NOT in the array. But my query returns the document with ObjectId("5bd9...").
Isn't the $in operator supposed to check if the _id in parameter is IN the array?
I wish it could return me a "0 fetched documents" because the id passed isn't in the array.
Thanks in advance
Your query is not right.
You can either find by id like so:
db.getCollection('adunits')
.find({_id: ObjectId("5bd9bc1ca4efae39d0b5a58e")})
to get a single document or use $in operator like so
db.getCollection('adunits')
.find({_id: { $in: ["5bf510156c154934150ef006","5bf5309e6c154934150f00a6",...]})
which will return documents which have one of the ids provided in the array.
You query condition finds adunits where _id = ObjectId("5bd9bc1ca4efae39d0b5a58e"), it returns the value that matches given condition. While $in operator should applied on a filed. Are you trying to achieve some thing like, find the documents that matches ids in given array.if yes , change your code to following. Visit mongodb official https://docs.mongodb.com/manual/reference/operator/query/in/.
db.getCollection('adunits').find(
{ "_id":
{ $in:
[ "5bf510156c154934150ef006",
"5bf5309e6c154934150f00a6",
"5bd9b874a4efae39d0b5a58d",
"5bf52a876c154934150efe4a"
]
}
});
I have a MongoDB collection with records having a "name" field, I am trying to perform a find query where the name field appears twice in the query. I want to exclude certain names, via $nin, and perform regex search for other names. It doesn't seem to be working, as it returns all records. If I just have the regex search or the $nin search, it works as expected.
db.users.find({name:{$nin:[current_user]}).cb(array) - works
db.users.find({name:new RegExp(/query/)}).cb(array) - works
db.users.find({name:{$nin:[current_user]}, name:new RegExp(/query/)}).cb(array) - does NOT work, the current_user is NOT excluded from the find result.
I have a feeling, the find command takes the last query for multiple occurrences of the same field, is that so? And how do I get around it?
Thanks for help,
Gary
Your query JSON object contains name field two times, and it breaks the query. Pay attention to the $and mongo query operator. There are two ways to construct correct query:
1) db.users.find({ $and: [{ name: { $nin: [current_user] } }, { name: { $regex: new RegExp(/query/) } }] })
2) db.users.find({ name: { $nin: [current_user], $regex: new RegExp(/query/) } })
Also, if you exclude only one user, you can use $ne operator instead of $nin.
I have a MongoDB collection with records having a "name" field, I am trying to perform a find query where the name field appears twice in the query. I want to exclude certain names, via $nin, and perform regex search for other names. It doesn't seem to be working, as it returns all records. If I just have the regex search or the $nin search, it works as expected.
db.users.find({name:{$nin:[current_user]}).cb(array) - works
db.users.find({name:new RegExp(/query/)}).cb(array) - works
db.users.find({name:{$nin:[current_user]}, name:new RegExp(/query/)}).cb(array) - does NOT work, the current_user is NOT excluded from the find result.
I have a feeling, the find command takes the last query for multiple occurrences of the same field, is that so? And how do I get around it?
Thanks for help,
Gary
Your query JSON object contains name field two times, and it breaks the query. Pay attention to the $and mongo query operator. There are two ways to construct correct query:
1) db.users.find({ $and: [{ name: { $nin: [current_user] } }, { name: { $regex: new RegExp(/query/) } }] })
2) db.users.find({ name: { $nin: [current_user], $regex: new RegExp(/query/) } })
Also, if you exclude only one user, you can use $ne operator instead of $nin.
Here's the sample document I'm trying to query
{
"_id":"asdf0-002f-42d6-b111-ade91df09249",
"user":[
{
"_id":"14bfgdsfg0-3708-46ee-8164-7ee1d029a507",
"n":"aaa"
},
{
"_id":"aasdfa89-5cfe-4861-8a9a-f77428158ca9",
"n":"bbb"
}
]
}
The document has 2 user references and contains the user _id and other misc information. I have the 2 user ids and am trying to get this document via only the user ids. I also don't know the order of the 2 ids. Is this a possible query?
col.findOne({
user:{
$all:[
{
_id:"14bfgdsfg0-3708-46ee-8164-7ee1d029a507"
},
{
_id:"aasdfa89-5cfe-4861-8a9a-f77428158ca9"
}
]
}
})
^^ Something that I've tried that doesn't work.
You are close with your $all attempt.
col.findOne({
"user._id":{
$all : [ "14bfgdsfg0-3708-46ee-8164-7ee1d029a507",
"aasdfa89-5cfe-4861-8a9a-f77428158ca9" ]
}
}
You can query a sub-document by wrapping it quotes. From there $all works against the values you are looking for.
Mongodb find a document with all subdocuments satisfying a condition shows a variation on this type of query.
ElemMatch should do the trick.
col.findOne({user:{$elemMatch:{"_id":"14bfgdsfg0-3708-46ee-8164-7ee1d029a507", "_id":"aasdfa89-5cfe-4861-8a9a-f77428158ca9" }}})