I have an abccollection collection whose documents look like:
{
id:123
focusPoint:89652.33
}
I want to retrieve all focusPoint values so that output looks like:
[89652.33, 89999.223, 99666.45, ...]
If you want to get a list without duplicates:
db.abccollection.distinct("focusPoint")
Otherwise, keeping duplicates:
db.abccollection.find({}, { _id: 0, focusPoint: 1 }).map((doc) => doc.focusPoint)
With that you will retrieve all the documents in the abccollection collection and project just the focusPoint field. The raw output of that query (before the map) will be an array of documents with a single field:
[{ focusPoint: 89652.33 }, { focusPoint: 89999.223 }, ...]
If you don't want MongoDB to do the .map in MongoDB, you can also do it in your application.
Related
Suppose I have this collection:
{
"_id":{
"$oid":"5fc2950883c843a134980620"
},
"name":"Legs",
"url":"https://www.youtube.com/watch?v=yXH-_hMf_Vs&t=527s",
"tags":[
{
"$oid":"5fc82b4969562b1584bed619"
},
{
"$oid":"5fcbe6846674f842d41c6bf1"
}
],
"exercises":[
{
"$oid":"5fc29042d8afdc3aec64e8f1"
},
{
"$oid":"5fce7025371a883f08e51239"
}
],
"date":{
"$date":{
"$numberLong":"1602277200000"
}
}
}
I want my query to return to the full data, which means that in each time I encounter object id I want to go to that collection and get the whole object. For example when I am in the tags array I want for each tag id to be replaced with the whole object from the tags collection.
How can that be achieved with a mongo query? I don't want to store all the objects in the same collection, i.e. the tags ids for example are foreign keys in this collection and primary keys in the tags collection.
Exactly the same should be applied for each array that contains ids, like exercises in this example.
I have multiple documents(3 documents in this example) in one collection that looks like this:
{
_id:123,
bizs:[{_id:'',name:'a'},{_id:'',name:'b'}]
},
{
_id:456,
bizs:[{_id:'',name:'e'},{_id:'',name:'f'}]
}
{
_id:789,
bizs:[{_id:'',name:'x'},{_id:'',name:'y'}]
}
Now, I want to update the bizs subdocument by matching with my array of ids.
That is to say, my array filter for update query is [123,789], which will match against the _id fields of each document.
I have tried using findByIdAndUpdate() but that doesn't allow an array for the update query
How can I update the 2 matching documents (like my example above) without having to put findByIdAndUpdate inside a forloop to match the array element with the _id?
You can not use findByIdAndUpdate when updating multiple documents, findByIdAndUpdate is from mongoose which is a wrapper to native MongoDB's findOneAndUpdate. When you pass a single string as a filter to findByIdAndUpdate like : Collection.findByIdAndUpdate({'5e179dac627ef7823643cd97'}, {}) - then mongoose will internally convert string to ObjectId() & form it as a filter like :_id : ObjectId('5e179dac627ef7823643cd97') to execute findOneAndUpdate. So it means you can only update one document at a time, So if you've multiple documents to be updated use update with option {multi : true} or updateMany.
Assume if you wanted to push a new object to bizs, this is how query looks like :
collection.updateMany({ _id: { $in: [123, 456] } }, {
$push: {
bizs: {
"_id": "",
"name": "new"
}
}
})
Note : Update operations doesn't return the documents in response rather they will return write result which has information about n docs matched & n docs modified.
I am trying to update items in an array with unique ObjectIds (meaning add an object ID to array object that are missing them)
If I have an array of shirt objects in my collection and I try this:
db.people.update({
$and : [
_id: ObjectId('5eeb44c6a042791d28a8641f'),
{
$or: [
{ 'shirts._id': { $eq:null } },
{ 'shirts._id':{ $exists:false } }
]
}
]
},{
$set: { 'shirts.$[]._id': new ObjectId() }
},{
"multi" : true
}
);
It generates IDENTICAL ObjectsIDs for each array element, I would put an unique index on this however, the use case probably wont see more then 2-3 items in the array with edge cases hitting 5-6, which seems like an abuse of an index
How can I update multiple records or multiple array objects with a unique ObjectId?
When you use $set you're telling mongo to set that value to all matching elements. If the elements in the array are already defined as schemas, mongo will issue new ObjectIds for each one of them automatically.
Alternatively, you can use forEach and iterate over each matching element creating a new ObjectId.
I have Generating the Dynamic Report from mongodb Collections. I fetch Data from one Collection and e.g client and take all client id in Array e.g ["5b7869dff0be71721f53d2e3","5b7869dff0be71721f53d2e4","5b7869dff0be71721f53d2e3"] When i I fetch data from other collection using In Array e.g {"clientId": { $in: inArray } } it give me empty result. because in array work if i put { "clientId": { $in: [ObjectId('5b785f243cc6c746af635dc8')] } } "ObjectId" word before the id. My Question is how i Put this ObjectId work in the array.
you can use map to map the array to an array of ObjectId
inArray = inArray.map( value => ObjectId(value) );
Say you have an document saved like this:
{
_id: "1",
thingy: {
moreStuff: [
{
_id:"a",
moreComplicated: [
{
_id:"a1",
info: "test"
},
... // More similar elements
]
},
... // More similar elements
]
}
}
Suppose you already have a way to get the query of the document:
db.getCollection("thingies").find({"_id": 1});
Now you're looking for a way to update the "info" section inside the "a1" object nested within all those other objects and arrays. The only catch to this is that "moreStuff" and "moreComplicated" arrays are being updated constantly, so aiming by array location (like thingy.morestuff.0.moreComplicated.0.info) won't work. The only way to do it is by looking up the unique mongoID of each object.
How would you query the arrays by matching an element to value instead of an index? Bonus points if you can have a "find" query return a similar object.