Here is how data are inserted in a "Products" MongoDB collection (using Meteor):
Products.insert(
{
productOne:
{
publicData:
{
pricePerUnit : 1,
label : "The first product"
},
privateData:
{
test1: "xxxxx",
test2: "xxxxx"
}
},
productTwo:
{
publicData:
{
pricePerUnit : 2,
label : "The second product"
},
privateData:
{
test1: "yyyyy",
test2: "yyyyy"
}
}
}
);
I would like to retrieve all the products, but without the "privateData" subdocuments, to get this:
{
productOne:
{
publicData:
{
pricePerUnit : 1,
label : "The first product"
}
},
productTwo:
{
publicData:
{
pricePerUnit : 2,
label : "The second product"
}
}
}
I tried several things with "$elemMatch" but honnestly I didn't succeed in anything, I have trouble understanding how I am even supposed to do that.
Would anyone have a suggestion? Any help would be greatly appreciated.
Thanks!
Your Query would be something Similar to this
Products.find({},{
fields: {
privateData: 0
}
}
privateData:0 will make sure that the field is omitted.
please Refer https://docs.mongodb.org/manual/tutorial/project-fields-from-query-results/ for more info
if you can use the aggregation framework you can use the $project operator:
db.<colletion_name>.aggregate( { $project: { publicData: 1} } );
And you will get back all of your documents with only the publicData field
Related
so i am struggling for 2 weeks on why does not my indexes get picked when i “explain” my queries.
i have this query:
{ “$and”: [
{ "extraProperties.class": "Residential" }, { "extraProperties.type": "Sale" }, { "extraProperties.propertyType": "Condo Apartment" }, { "extraProperties.propertyTypeStyle": "Apartment" } ] }
the above query wont pick this index :
{ “extraProperties.class”:1 , “extraProperties.type” : 1, “extraProperties.propertyType”:1,“extraProperties.propertyTypeStyle”:1}
i have been testing everything these days and finally i decided to flatten the hierarchy and now my query looks like this:
{ “$and”: [
{ “class”: “Residential” }, { “type”: “Sale” }, { “propertyType”: “Condo Apartment” }, { “propertyTypeStyle”: “Apartment” }
] }
now the above query will pick this index :
{ “class”:1 , “type” : 1, “propertyType”:1,“propertyTypeStyle”:1}
could someone explain what the hell is going on there?!?!
explain result:
https://drive.google.com/file/d/1bs_mqO-1FEBHQ_FsBWgP2TQ2jeiQz4q_/view?usp=sharing
I have a tricky mongoDB problem that I have never encountered.
The Documents:
The documents in my collection have a search object containing named keys and array values. The keys are named after one of eight categorys and the corresponding value is an array containing items from that category.
{
_id: "bRtjhGNQ3eNqTiKWa",
/* */
search :{
usage: ["accounting"],
test: ["knowledgetest", "feedback"]
},
test: {
type:"list",
vals: [
{name:'knowledgetest', showName: 'Wissenstest'},
{name:'feedback', showName: '360 Feedback'},
]
},
usage: {
type:"list",
vals: [
{name:'accounting', showName: 'Accounting'},
]
}
},
{
_id: "7bgvegeKZNXkKzuXs",
/* */
search :{
usage: ["recruiting"],
test: ["intelligence", "feedback"]
},
test: {
type:"list",
vals: [
{name:'intelligence', showName: 'Intelligenztest'},
{name:'feedback', showName: '360 Feedback'},
]
},
usage: {
type:"list",
vals: [
{name:'recruiting', showName: 'Recruiting'},
]
}
},
The Query
The query is an object containing the same category - keys and array - values.
{
usage: ["accounting", "assessment"],
test : ["feedback"]
}
The desired outcome
If the query is empty, I want all documents.
If the query has one category and any number of items, I want all the documents that have all of the items in the specified category.
If the query has more then one category, I want all the documents that have all of the items in all of the specified categorys.
My tries
I tried all kinds of variations of:
XX.find({
'search': {
"$elemMatch": {
'tool': {
"$in" : ['feedback']
}
}
}
No success.
EDIT
Tried: 'search.test': {$all: (query.test ? query.test : [])} which gives me no results if I have nothing selected; the right documents when I am only looking inside the test category; and nothing when I additionally look inside the usage category.
This is at the heart of my app, thus I historically put up a bounty.
let tools = []
const search = {}
for (var q in query) {
if (query.hasOwnProperty(q)) {
if (query[q]) {
search['search.'+q] = {$all: query[q] }
}
}
}
if (Object.keys(query).length > 0) {
tools = ToolsCollection.find(search).fetch()
} else {
tools = ToolsCollection.find({}).fetch()
}
Works like a charm
What I already hinted at in the comment: your document structure does not support efficient and simple searching. I can only guess the reason, but I suspect that you stick to some relational ideas like "schemas" or "normalization" which just don't make sense for a document database.
Without digging deeper into the problem of modeling, I could imagine something like this for your case:
{
_id: "bRtjhGNQ3eNqTiKWa",
/* */
search :{
usage: ["accounting"],
test: ["knowledgetest", "feedback"]
},
test: {
"knowledgetest" : {
"showName": "Wissenstest"
},
"feedback" : {
"showName": "360 Feedback"
}
},
usage: {
"accounting" : {
"values" : [ "knowledgetest", "feedback" ],
"showName" : "Accounting"
}
}
},
{
_id: "7bgvegeKZNXkKzuXs",
/* */
search : {
usage: ["recruiting"],
test: ["intelligence", "feedback"]
},
test: {
"intelligence" : {
showName: 'Intelligenztest'
},
"feedback" : {
showName: '360 Feedback'
}
},
usage: {
"recruiting" : {
"values" : [ "intelligence", "feedback" ],
"showName" : "Recruiting"
}
}
}
Then, a search for "knowledgetest" and "feedback" in "accounting" would be a simple
{ "usage.accounting.values" : { $all : [ "knowledgetest", "feedback"] } }
which can easily be used multiple times in an and condition:
{
{ "usage.accounting.values" : { $all : [ "knowledgetest", "feedback"] } },
{ "usage.anothercategory.values" : { $all [ "knowledgetest", "assessment" ] } }
}
Even the zero-times-case matches your search requirements, because an and-filter with none of these criteria yields {} which is the find-everything filter expression.
Once more, to make it absolutely clear: when using mongo, forget everything you know as "best practice" from the relational world. What you need to consider is: what are your queries, and how can my document model support these queries in an ideal way.
In mongo I store object that have field "titleComposite". This field contains array of title object, like this:
"titleComposite": [
"0": {
"titleType": "01",
"titleText": "Test cover uploading"
}
]
I'm perfoming query and I would like to receive only "titleText" value for the returned values. Here is an example of my query:
db.onix_feed.find({"addedBy":201, "mediaFileComposite":{$exists:false}}, {"isbn13":1,"titleComposite.titleText":1})
In the results I see values like
{
"_id" : ObjectId("559ab286fa4634f309826385"),
"titleComposite" : [ { "titleText" : "The Nonprofit World" } ],
"isbn13" : "9781565495296"
}
Is there any way to get rid of "titleComposite" wrapper object and receive only titleText? For example, take titleText of the first element only?
Would appreciate any help
You can mongodb aggregation to achieve your expected result. Re-arrange your query as following...
db.onix_feed.aggregate([
{
$match: {
$and: [
{"addedBy":201},
{"mediaFileComposite":{$exists:false}}
]
}
},
{
$project : { titleText: "$titleComposite.titleText",
"isbn13" : 1 }
}
])
I have a MongoDB document structured like this:
{
"_id": ObjectId("50cf904a07ef604c8cc3d091"),
"lessons": {
"0": {
"lesson_name": "View and Edit Lists",
"release_time": ISODate("2012-12-17T00:00:00Z"),
"requires_anim": false,
"requires_qq": true
},
"1": {
"lesson_name": "Leave a Tip",
"release_time": ISODate("2012-12-18T00:00:00Z"),
"requires_anim": false,
"requires_qq": true
}
}
}
I have a number of such documents. I'd like to get all documents for which the release time of a lesson is greater than or equal to a given time. Here's the query I wrote:
db.lessons.find({"lessons.release_time":{"$gte": ISODate("2012-12-16")}});
But this is not returning any documents. Any ideas on what I'm doing wrong and how to correct it. Thanks.
Here's the result of my testing:
> db.testc.insert( { lessons: [
{release_time: ISODate("2012-12-17T00:00:00Z")},
{release_time: ISODate("2012-12-18T00:00:00Z")}
] } )
> db.testc.find({"lessons.release_time":{"$gte": ISODate("2012-12-16")}})
{ "_id" : ObjectId("50cfa093ab08a4592c73f927"),
"lessons" : [
{ "release_time" : ISODate("2012-12-17T00:00:00Z") },
{ "release_time" : ISODate("2012-12-18T00:00:00Z") }
] }
Your query is fine but, as others have pointed out, most likely your data is not structured as an array.
I am currently evaluating the efficiency of different databases for a use case. In Mongodb, would like to store around 1 million objects with the following structure. Each object will have between 5 and 10 objects in the foo array.
{
name:"my name",
foos:[
{
foo:"...",
bar:"..."
},
{
foo:"...",
bar:"..."
},
{
foo:"...",
bar:"..."
}
]
}
I often need to search for objects which where the foos collection contains an object with a specific property, e.g.:
// mongo collection
[
{
name:'my name',
foos:[
{
foo:'one_foo',
bar:'a_bar'
},
{
foo:'two_foo',
bar:'b_bar'
}
]
},
{
name:'another name',
foos:[
{
foo:'another foo',
bar:'a_bar'
},
{
foo:'just another foo',
bar:'c_bar'
}
]
}
]
// search (pseudo code)
{ foos: {$elemMatch: {bar: 'c_bar'}} }
// returns
{
name:'another name',
foos:[
{
foo:'another foo',
bar:'a_bar'
},
{
foo:'just another foo',
bar:'c_bar'
}
]
}
Can this efficiently be done with mongo and how should the indexes be set?
I don't want you to evaluate performance for me, just an idea how mongo performs for my use case or how optimization could look like.
MongoDB has documentation explaining how to create indexes on embedded documents, through dot notation:
Dot Notation (Reaching into Objects)
> db.blogposts.findOne()
{ title : "My First Post", author: "Jane",
comments : [{ by: "Abe", text: "First" },
{ by : "Ada", text : "Good post" } ]
}
> db.blogposts.find( { "comments.by" : "Ada" } )
> db.blogposts.ensureIndex( { "comments.by" : 1 } );
As for the performance characteristic... just test it with your dataset.