I'm working on mongo, in this time in need to remove a specific element from array nested in another one, the structure is like the following:
{
"_id" : ObjectId("5e616314946b6d3ac4ed8252"),
"uid" : "5db069478556622b4a0adca5",
"areas" : [
{
"name" : "mexico",
"elements" : [
"23452345",
"24454675"
],
},
{
"name" : "usa",
"elemets" : [
"123123123",
"1234334"
],
}
]
}
So I need a query that lets me remove any element in "elements" property.
I tried with this query but I couldn't reach it.
db.areas.update(
{ },
{ $pull:
{ areas: {
$elemMatch: {
elements: { $eq : "123123123" }
}
}
}
},
{ multi:false }
);
This just said
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })
Here is the update for removing the specific array element in a sub-array (elements).
Note that to remove (pull) the specified element (elements value "24454675"), you need to specify the outer-array's element matching condition (note that there are two elements in the outer-array field areas).
db.areas.update(
{ "areas.name": "mexico" },
{ $pull: { "areas.$.elements": "24454675" } }
)
NOTE: If you don't specify the { "areas.name": "mexico" } condition, the whole sub-document of the areas array will be removed.
Related
I have the following document structure in a MongoDB collection :
{
"A" : [ {
"B" : [ { ... } ]
} ]
}
I'd like to update this to :
{
"A" : [ {
"B" : [ { ... } ],
"x" : [],
"y" : { ... }
} ]
}
In other words, I want the "x" and "y" fields to be added to the first element of the "A" array without loosing "B".
Ok as there is only one object in A array you could simply do as below :
Sample Collection Data :
{
"_id" : ObjectId("5e7c3cadc16b5679b4aeec26"),
A:[
{
B: [{ abc: 1 }]
}
]
}
Query :
/** Insert new fields into 'A' array's first object by index 0 */
db.collection.updateOne(
{ "_id" : ObjectId("5e7c3f77c16b5679b4af4caf") },
{ $set: { "A.0.x": [] , "A.0.y" : {abcInY :1 }} }
)
Output :
{
"_id" : ObjectId("5e7c3cadc16b5679b4aeec26"),
"A" : [
{
"B" : [
{
"abc" : 1
}
],
"x" : [],
"y" : {
"abcInY" : 1.0
}
}
]
}
Or Using positional operator $ :
db.collection.updateOne(
{ _id: ObjectId("5e7c3cadc16b5679b4aeec26") , 'A': {$exists : true}},
{ $set: { "A.$.x": [] , "A.$.y" : {abcInY :1 }} }
)
Note : Result will be the same, but functionally when positional operator is used fields x & y are inserted to first object of A array only when A field exists in that documents, if not this positional query would not insert anything (Optionally you can check A is an array condition as well if needed). But when you do updates using index 0 as like in first query if A doesn't exist in document then update would create an A field which is an object & insert fields inside it (Which might cause data inconsistency across docs with two types of A field) - Check below result of 1st query when A doesn't exists.
{
"_id" : ObjectId("5e7c3f77c16b5679b4af4caf"),
"noA" : 1,
"A" : {
"0" : {
"x" : [],
"y" : {
"abcInY" : 1.0
}
}
}
}
However, I think I was able to get anothe#whoami Thanks for the suggestion, I think your first solution should work. However, I think I was able to get another solution to this though I'm not sure if its better or worse (performance wise?) than what you have here. My solution is:
db.coll.update( { "_id" : ObjectId("5e7c4eb3a74cce7fd94a3fe7") }, [ { "$addFields" : { "A" : { "x" : [ 1, 2, 3 ], "y" : { "abc" } } } } ] )
The issue with this is that if "A" has more than one array entry then this will update all elements under "A" which is not something I want. Just out of curiosity is there a way of limiting this solution to only the first entry in "A"?
Here is my news document structure
{
"_id" : ObjectId("5bff0903bd9a221229c7c9b2"),
"title" : "Test Page",
"desc" : "efdfr",
"mediaset_list" : [
{
"_id" : ObjectId("5bfeff94bd9a221229c7c9ae"),
"medias" : [
{
"_id" : ObjectId("5bfeff83bd9a221229c7c9ac"),
"file_type" : "png",
"file" : "https://aws.com/gg.jpg",
"file_name" : "edf.jpg"
},
{
"_id" : ObjectId("5bfeff83bd9a221229c7c9ad"),
"file_type" : "mov",
"file" : "https://aws.com/gg.mov",
"file_name" : "abcd.mov"
}
]
}
]}
The queries that i've tried are given below
Approach 1
db.news.find_and_modify({},{'$pull': {"mediaset_list": {"medias": {"$elemMatch" : {"_id": ObjectId('5bfeff83bd9a221229c7c9ac')}} }}})
Approach 2
db.news.update({},{'$pull': {"mediaset_list.$.medias": {"_id": ObjectId('5bfeff83bd9a221229c7c9ac')}} })
Issue we are facing
The above queries are removing entire elements inside 'mediaset_list' . But i only want to remove the element inside 'medias' matching object ID.
Since you have two nested arrays you have to use arrayFilters to indicate which element of outer array should be modified, try:
db.news.update({ _id: ObjectId("5bff0903bd9a221229c7c9b2") },
{ $pull: { "mediaset_list.$[item].medias": { _id: ObjectId("5bfeff83bd9a221229c7c9ad") } } },
{ arrayFilters: [ { "item._id": ObjectId("5bfeff94bd9a221229c7c9ae") } ] })
So item is used here as a placeholder which will be used by MongoDB to determine which element of mediaset_list needs to be modified and the condition for this placeholder is defined inside arrayFilters. Then you can use $pull and specify another condition for inner array to determine which element should be removed.
From #micki's mongo shell query (Answer above) , This is the pymongo syntax which will update all news document with that media id .
db.news.update_many({},
{
"$pull":
{ "mediaset_list.$[item].medias": { "_id": ObjectId("5bfeff83bd9a221229c7c9ad") } } ,
},
array_filters=[{ "item._id": ObjectId("5bfeff94bd9a221229c7c9ae")}],
upsert=True)
I'm able to decrease a value in a nested array, but I want to check that the value is greater than zero (so never go to the negative numbers). For example, I have this:
{
"_id" : ObjectId("5a3b0bd69c0000c2a1d839af"),
"slots" : [
{
"id" : "V2qlAEk7Wp0tWwlyWSfX7KRZ",
"number" : 5.0
},
.......
.......
{
"id" : "VfB4f8G1KcgRA8qx0aby5nI0",
"number" : 0.0
}]
}
{
"_id" : ObjectId("5a3b0bd69c0000c2a1d839ag"),
"slots" : [
{
"id" : "V2qlAEEESbrEB4bwberbResbd",
"number" : 10.0
},
.......
.......
{
"id" : "DFwseEb5enRbfsbre54rtFfds",
"number" : 1.0
}]
}
If I want to decrease the number value of the first document [id=5a3b0bd69c0000c2a1d839af] of the slots.id = V2qlAEk7Wp0tWwlyWSfX7KRZ, I use:
db.getCollection('schedulers').update(
{
"_id" : ObjectId("5a3b0bd69c0000c2a1d839af"),
"slots.id" :"V2qlAEk7Wp0tWwlyWSfX7KRZ"
},
{
"$inc":{"slots.$.number":-1}
})
But I don't know how to check if the number is greater than 0 before decrease the value. I tried to use The filtered positional operator $[<identifier>], but I have an error:
db.getCollection('schedulers').update(
{
"_id" : ObjectId("5a3b0bd69c0000c2a1d839af"),
"slots.id" :"V2qlAEk7Wp0tWwlyWSfX7KRZ"
},
{
"$inc":{"slots.$[elm].number":-1}
},
{
arrayFilters: [ { "elm.number": {"$gt" : 0}} ]
})
The error is:
cannot use the part (slots of slots.$[elm].number) to traverse the element....
Also, apply the condition in the first part of the query doesn't fix the problem, cause mongo traverses all the array, so also if the number is zero it simply move to another element in the array until it finds number > 0 and when it finds it, it starts to decrease the number value of another element completely ignoring the two id conditions [because now the $ then point to another element of the array]:
db.getCollection('schedulers').update(
{
"_id" : ObjectId("5a3b0bd69c0000c2a1d839af"),
"slots.id" :"V2qlAEk7Wp0tWwlyWSfX7KRZ",
"slots.number":{"$gt" : 0}
},
{
"$inc":{"slots.$.number":-1}
})
I think the correct way to obtain what I want is to use the arrayFilters but I don't understand where is the problem.
Fixed using:
db.getCollection('schedulers').update(
{
"_id" : ObjectId("5a3b0bd69c0000c2a1d839af"),
"slots" :
{
"$elemMatch":
{
"id":"V2qlAEk7Wp0tWwlyWSfX7KRZ",
"number":
{
"$gt" : 0
}
}
}
},
{
"$inc":
{
"slots.$.number":-1
}
})
Thanks
There is an bson document:
{
"_id" : ObjectId("5718441f5116a60b08000b8c"),
"mails" : [
{
"id" : 2,
"a" : [
{
"a" : 1
},
{
"a" : 2
}
]
},
{
"id" : 1,
"a" : [
{
"a" : 1
},
{
"a" : 2
}
]
}
]
}
I need to return and clear the array "a" which belong to "mails.id == x" for given document. So I use findAndModify like:
db.mail.findAndModify({query: {"_id":ObjectId("5718441f5116a60b08000b8c")}, update: {$set:{"mails.$.a":[]}}, new: false, fields:{"mails":{$elemMatch:{"id":1}}}})
However this don't work. The problem is the $set should apply on one document in array rather than the whole document. So I need a projection to project it out.
If I left update to blank, it will return the desired part:
{
"_id" : ObjectId("5718441f5116a60b08000b8c"),
"mails" : [
{
"id" : 1,
"a" : [
{
"a" : 1
},
{
"a" : 2
}
]
}
]
}
But I don't know how to clear the array 'a' in 'mails'
You have to specify array element match in the query:
db.mail.findAndModify({query: {"_id":ObjectId("5718441f5116a60b08000b8c"), "mails":{$elemMatch:{"id":1}}}, update: {$set:{"mails.$.a":[]}}, new: false, fields:{"mails":{$elemMatch:{"id":1}}}})
mails.$ in you update matches the first matched element in the doc, so you have to match it in the query. Also, this query will update the doc, but it will return the old version, since you use new: false, if you want to get the updated version set it to true.
In MongoDB, I'm trying to write a query to add elements from an array to an existing document, but instead of adding the elements as objects:
property: ObjectID(xxx)
the elements are getting added as just
ObjectID(xxx)
Forgive me if I get the terminology wrong. I'm completely new to MongoDB; I normally only work with relational databases. How do I properly add these new elements?
I have a collection called auctions which has two fields: ID and properties. Properties is an array of objects named property. Here's an example with two auction documents:
** I changed the object IDs to make them easier to reference in our discussion
Collection db.auctions
{
"_id" : ObjectId("abc"),
"properties" : [
{
"property" : ObjectId("prop1")
},
{
"property" : ObjectId("prop2")
},
{
"property" : ObjectId("prop3")
}]
}
{
"_id" : ObjectId("def"),
"properties" : [
{
"property" : ObjectId("prop97")
},
{
"property" : ObjectId("prop98")
}]
}
I want to add 3 new properties to auction "abc". How do I do this?
Here's is what I tried:
I have an array of properties that looks like this:
Array PropsToAdd
[
ObjectId("prop4"),
ObjectId("prop5"),
ObjectId("prop6")
]
I wrote an update query to push these properties into the properties array in auctions:
db.auctions.update(
{"_id": "abc"}
,
{ $push: { properties: { $each: PropsToAdd } } }
);
This query gave the result below. Notice that instead of adding elements named property with a value from my array, it's just added my values from my array. I obviously need to add that "property" part, but how do I do that?
Collection db.auctions (_id "abc" only)
{
"_id" : ObjectId("abc"),
"properties" : [
{
"property" : ObjectId("prop1")
},
{
"property" : ObjectId("prop2")
},
{
"property" : ObjectId("prop3")
},
ObjectId("prop4"),
ObjectId("prop5"),
ObjectId("prop6"),
ObjectId("prop7")]
}
The result I'm looking for is this:
Collection db.auctions (_id "abc" only)
{
"_id" : ObjectId("abc"),
"properties" : [
{
"property" : ObjectId("prop1")
},
{
"property" : ObjectId("prop2")
},
{
"property" : ObjectId("prop3")
},
{
"property" : ObjectId("prop4")
},
{
"property" : ObjectId("prop5")
},
{
"property" : ObjectId("prop6")
}
}
Here is some further information on that array of properties I'm adding. I get it from running these queries. Perhaps one of them needs changed?
This query gets an array of current properties:
var oldActiveProperties = db.properties.distinct( "saleNumber", { "active": true, "auction": ObjectId("abc") } );
Then those results are used to find properties in the new file that weren't in the old file:
var PropsToAdd = db.newProperties.distinct(
"_id"
, { "saleNumber": { "$nin": oldActiveProperties }, "active": true}
);
The resulting array is what I need to add to the auctions collection.
Use the JavaScript's native map() method to map the array into an array of documents. The following shows this:
var PropsToAdd = db.newProperties.distinct("_id",
{ "saleNumber": { "$nin": oldActiveProperties }, "active": true}
).map(function (p) { return { property: p }; });
db.auctions.update(
{"_id": "abc"},
{ $push: { "properties": { "$each": PropsToAdd } } }
);