I am developing a web platform for people who is learning languages, I have a collection for users like that:
{
"_id" : ObjectId("54a15e7e3453b5741a6c7be0"),
"name" : "Miguel Lopez",
"lng" : [
{
"ES" : 5
},
{
"EN" : 4
},
{
"IT" : 3
}
],
"email" : "miguel#gmail.com",
"password" : "123456"
}
In "lng" field I save the languages that this user is learning, each language have a level between 1 and 5. To get the list of users who are learning "ES" and have level 5, I use this query:
db.users.find({lng : {ES:5}})
And it´s working perfectly, but when I want the get users who have a specific language (for example "EN") with a level less than 5, I use this query:
db.users.find({lng : {EN:{$lt: 5}}})
But this query doesn´t work, and I dont know the reason, when I try to execute this query in Robomongo I get this message: "Script executed succesfully, but there is no results to show"
You need to use $elemMatch or dot notation
db.users.find({lng : {$elemMatch: {EN:{$lt: 5}}}})
db.users.find({ "lng.EN" : { "$lt" : 5 } })
Related
> db.movmodels.findOne()
{
"_id" : ObjectId("55320b0e0e9e0d9d0540593c"),
"username" : "punk",
"favMovies" : [
{
"alternate_ids" : {
"imdb" : "0137523"
},
"abridged_cast" : [
{
"characters" : [
"Tyler"
],
"id" : "162652627",
"name" : "Brad Pitt"
},
{
"characters" : [
"Narrator"
],
"id" : "162660884",
"name" : "Edward Norton"
},
{
"characters" : [
"Robert"
],
"id" : "162676383",
"name" : "Meat Loaf"
},
{
"characters" : [
"Angel Face"
],
"id" : "162653925",
"name" : "Jared Leto"
},
{
"characters" : [
"Boss"
],
"id" : "770706064",
"name" : "Zach Grenier"
}
],
"synopsis" : "",
"ratings" : {
"audience_score" : 96,
"audience_rating" : "Upright",
"critics_score" : 80,
"critics_rating" : "Certified Fresh"
},
"release_dates" : {
"dvd" : "2000-06-06",
"theater" : "1999-10-15"
},
"critics_consensus" : "",
"runtime" : 139,
"mpaa_rating" : "R",
"year" : 1999,
"title" : "Fight Club",
**"id" : "13153"**
}
],
"__v" : 0
}
This is my data in mongodb.
As I am new to mongodb I wanted to know query to get movie with a particular id.
The query that I tried is. I need to get the movie based on id so that I can remove it from my database
db.movmodels.findOne({username:"punk"},{favMovies:{id:13153}})
but this gives me error.
2015-04-18T05:41:26.221-0400 E QUERY Error: error: {
"$err" : "Can't canonicalize query: BadValue ported projection option: favMovies: { id: 13153.0 }",
"code" : 17287
}
at Error (<anonymous>)
at DBQuery.next (src/mongo/shell/query.js:259:15)
at DBCollection.findOne (src/mongo/shell/collection.js:188:22)
at (shell):1:14 at src/mongo/shell/query.js:259
There are several problems with your query:
The second parameter to find() is a projection, not part of the query. What you want is to supply one document for the query that has two properties: {"username" : "punk", favMovies : { ... } }
However, you also don't want to compare the entire sub-document favMovies, but you only want to match on one of its properties, the id, which requires to 'reach into the object' using the dot operator: {username:"punk", "favMovies.id" : 13153}.
However, that will probably not work yet, because 13153 is not the same as "13153", the latter being a string while the former is a number in JSON.
db.movmodels.findOne({username:"punk", "favMovies.id" : "13153"})
Keep in mind, however, that this will find the entire document for the user named "punk". I'm not sure what exactly your data structure should look like, but it appears you'll have to $pull the movie from the user. In general, I'd say you're embedding too much data into the user, but that's hard to tell without knowing the exact use case.
Here you go:
If you just wanted to get first user who has this fav movie:
db.movmodels.findOne({"favMovies.id": 13153});
And, if you want to know if that user has that movie as favorite.
db.movmodels.findOne({"favMovies.id": 13153, username:"punk"});
Second argument in the findOne is used to only return particular field.
You can use also $elemMatch projection operator (not to be confused with the $elemMatch query operator)
db.movmodels.find({username:"punk"},{favMovies:{$elemMatch:{id:"13153"}}});
`
If you want to find a movie that has another movie (with id 13153) in 'favMovies' array, then write the query as below:
db.movmodels.findOne({username:"punk",'favMovies.id':13153})
And if you want to find a movie with _id 55320b0e0e9e0d9d0540593cwrite the following query:
db.movmodels.findOne({username:"punk",'_id':ObjectId("55320b0e0e9e0d9d0540593c")})
I'm trying to get this simple query to just get a subfield out of a collection. So far I just keep getting the entire field so what should I correct to just print out the subfield I'm looking for?
I'm trying to list the titles (only) of all movies with a rank of less than 9.2 and with at least 5 votes, print the titles in alphabetical order.
This is my query so far but its incorrect and just returns the whole object. How can I get it to return just the rank and votes of Jungle Book? Thank you very much in advance.
db.collections.find({"title": {$exists:true}}, {"_id":0, "rank":{$lt : 9.2}})
{ "_id" : ObjectId("10"), "rank" : 6, "votes" : 8.8, "title" : "Jungle Book" }
{ "_id" : ObjectId("11"), "rank" : 8, "votes" : 8.7, "title" : "Spawn" }
You need to have the filter/query all in the first parameter. The second parameter is a set of booleans for which properties it should return.
db.ratings.find({title: {$exists:true}, rank:{$lt : 9.2},
votes: {$gte : 5 } }, {_id:0, title:1}).sort({title:1})
This will return a set that looks like this:
[{"title" : "Jungle Book"}, {"title" : "Spawn"}]
If you want only the titles, and not in object form you could use "distinct" here:
db.ratings.distinct('title', {title: {$exists:true},
rank:{$lt : 9.2}, votes: {$gte : 5 } });
The distinct query should be sorted by default. If you want to sort it a different way you'll need to use an aggregate query.
I've run this EXACT set of code against my local install:
MongoDB shell version: 2.4.8
connecting to: test
rs0:PRIMARY> db.ratings.insert({rank:6, votes:8.8, title:"Jungle Book"});
rs0:PRIMARY> db.ratings.insert({rank:8, votes:8.7, title:"Spawn"});
rs0:PRIMARY> db.ratings.find({title: {$exists:true}, rank:{$lt : 9.2}, votes: {$gte : 5 } }, {_id:0, title:1}).sort({title:1})
{ "title" : "Jungle Book" }
{ "title" : "Spawn" }
rs0:PRIMARY> db.ratings.distinct('title', {title: {$exists:true}, rank:{$lt : 9.2}, votes: {$gte : 5 } });
[ "Jungle Book", "Spawn" ]
rs0:PRIMARY>
I am trying to filter mongo data by using the below query in mongodb version 2.6.1 but getting error.
MongoDB version 2.4.6 (Working):
> db.BC_1839.find({data: {$elemMatch:{$where : "this.First_name.toLowerCase().indexOf('kim') ==0"}}});
output:
{
"_id" : ObjectId("53719a9d5b9e5c8c110001b9"),
"data" : [
{
"First_name" : "Kimberely",
"Last_name" : "Weyman",
"Company_name" : "Scientific Agrcltl Svc Inc",
"Address" : "7721 Harrison St",
"City" : "Kingsway West",
"State" : "NS",
"Post" : "2208",
"Phone1" : "02-7091-8948",
"Phone2" : "0441-151-810",
"Email" : "kweyman#weyman.com.au",
"Web" : "http://www.scientificagrcltlsvcinc.com.au",
"active" : "true"
}
],
"history" : [
{
"timestamp" : "2014-05-13 06:07:55",
"event": "creation",
"createdby" : "Srikesh Infotech",
"creation_data" : [
{
"crm_base_contact_id" : "1839",
"crm_imported_files_id" : "1464"
}
]
},
{
"timestamp" : "2014-05-13 06:09:05",
"event" : "Task",
"createdby" : "Srikesh Infotech",
"Task_data" : [
{
"Campaign ID" : "193",
"Campagin Name" : "Test Campa1"
}
]
}
],
"ref" : [
{ "crm_base_contact_id" : "1839", "crm_imported_files_id" : "1464" }
]
}
MongoDB version 2.6.1(Not Working):
> db.BC_1839.find({data: {$elemMatch:{$where : "this.First_name.toLowerCase().indexOf('kim') ==0"}}});
output:
error: {
"$err" : "Can't canonicalize query: BadValue $elemMatch cannot contain $
where expression",
"code" : 17287
}
Same query executes in mongodb version 2.4.6 but not in mongodb version 2.6.1 Why???
It shouldn't have worked in earlier versions at all, as at the very least you have modified the scoping of this to now refer to "data" as a top level element. In short, this is no longer allowed and you really should not be using JavaScript methods unless you absolutely have to. Even then, there is probably still a better way in most cases.
But in fact this is an un-necessary use of JavaScript matching as it is not required when there are other operators existing that will do this.
You should be using a $regex form instead:
db.docs.find({ "data.First_name": /^kim/i })
Or anywhere within the field, remove the caret ^:
db.docs.find({ "data.First_name": /kim/i })
Which is pretty much as inefficient as JavaScript execution but not as much as there is not the overhead of processing through that interpreter engine. And of course it works everywhere.
Also think about what a query relying on JavaScript to resolve is actually doing:
Invokes a JavaScript interpreter instance
Converts BSON document types per document to JavaScript types
Evaluates JavaScript code in the interpreter per document
Casts JavaScript true|false back as a result per document
Considering that $regex ( but with a case insensitive match which is not optimal ) is doing the same operations but using the "pcre" C library natively without conversion and recasting per document, then it is clearly the sane choice of the two.
I have two collection as bellow products has reference of user. i search product by name & in return i want combine output of product and user using map reduce method
user collection
{
"_id" : ObjectId("52ac5dd1fb670c2007000000"),
"company" : {
"about" : "This is textile machinery dealer",
"contactAddress" : [{
"address" : "abcd",
"city" : "52ac4bc6fb670c1007000000",
"zipcode" : "39as46as80"
},{
"address" : "abcd",
"city" : "52ac4bc6fb670c1007000000",
"zipcode" : "39as46as80"
}],
"fax" : "58784868",
"mainProducts" : "ads,asd,asd",
"mobileNumber" : "9537236588",
"name" : "krishna steels",
}
"user" : ObjectId("52ac4eb7fb670c0c07000000")
}
product colletion
{
"_id" : ObjectId("52ac5722fb670cf806000002"),
"category" : "52a2a9cc48a508b80e00001d",
"deliveryTime" : "10 days after received the ",
"price" : {
"minPrice" : "2000",
"maxPrice" : "3000",
"perUnit" : "5288ac6f7c104203e0976851",
"currency" : "INR"
},
"productName" : "New Mobile Solar Charger with Carabiner",
"rejectReason" : "",
"status" : 1,
"user" : ObjectId("52ac4eb7fb670c0c07000000")
}
This cannot be done. Mongo support Map Reduce only on one collection. You could try to fetch and merge in a java collection. Couple of days back I solved a similar problem using java collection.
Click to see similar response about joins and multi collection not supported in mongo.
This can be done using two map reduces.
You run your first MR and then you reduce out the second MR onto the results of the first.
You shouldn't do this though. JOINs are not designed to be done through MR, in fact it sounds like you are trying to do this MR with inline output which in itself is a very bad idea.
MRs are not designed to run inline to the application.
You would be better off doing the JOIN else where.
I've "users" collection with a "watchlists" field, which have many inner fields too, one of that is "arrangeable_values" (the second field within "watchlists").
I need to find for each user in "users" collection, each "arrangeable_values" within "watchlists".
How can I do that with mongodb shell ?
Here is an example of data model :
> db.users.findOne({'nickname': 'superj'})
{
"_id" : ObjectId("4f6c42f6018a590001000001"),
"nickname" : "superj",
"provider" : "github",
"user_hash" : null,
"watchlists" : [
{
"_id" : ObjectId("4f6c42f7018a590001000002"),
"arrangeable_values" : {
"description" : "My introduction presentation to node.js along with sample code at various stages of building a simple RESTful web service with journey, cradle, winston, optimist, and http-console.",
"tag" : "",
"html_url" : "https://github.com/indexzero/nodejs-intro"
},
"avatar_url" : "https://secure.gravatar.com/avatar/d43e8ea63b61e7669ded5b9d3c2e980f?d=https://a248.e.akamai.net/assets.github.com%2Fimages%2Fgravatars%2Fgravatar-140.png",
"created_at" : ISODate("2011-02-01T10:20:29Z"),
"description" : "My introduction presentation to node.js along with sample code at various stages of building a simple RESTful web service with journey, cradle, winston, optimist, and http-console.",
"fork_" : false,
"forks" : 13,
"html_url" : "https://github.com/indexzero/nodejs-intro",
"pushed_at" : ISODate("2011-09-12T17:54:58Z"),
"searchable_values" : [
"description:my",
"description:introduction",
"description:presentation",
"html_url:indexzero",
"html_url:nodejs",
"html_url:intro"
],
"tags_array" : [ ],
"watchers" : 75
},
{
"_id" : ObjectId("4f6c42f7018a590001000003"),
"arrangeable_values" : {
"description" : "A Backbone alternative idea",
"tag" : "",
"html_url" : "https://github.com/maccman/spine.todos"
},
"avatar_url" : "https://secure.gravatar.com/avatar/baf018e2cc4616e4776d323215c7136c?d=https://a248.e.akamai.net/assets.github.com%2Fimages%2Fgravatars%2Fgravatar-140.png",
"created_at" : ISODate("2011-03-18T11:03:42Z"),
"description" : "A Backbone alternative idea",
"fork_" : false,
"forks" : 31,
"html_url" : "https://github.com/maccman/spine.todos",
"pushed_at" : ISODate("2011-11-20T22:59:45Z"),
"searchable_values" : [
"description:a",
"description:backbone",
"description:alternative",
"description:idea",
"html_url:https",
"html_url:github",
"html_url:com",
"html_url:maccman",
"html_url:spine",
"html_url:todos"
],
"tags_array" : [ ],
"watchers" : 139
}
]
}
For the document above, the following find() query would extract both the "nickname" of the document, and its associated "arrangeable_values" (where the document is in the users collection):
db.users.find({}, { "nickname" : 1, "watchlists.arrangeable_values" : 1 })
The result you get for your single document example would be:
{ "_id" : ObjectId("4f6c42f6018a590001000001"), "nickname" : "superj",
"watchlists" : [
{ "arrangeable_values" : { "description" : "My introduction presentation to node.js along with sample code at various stages of building a simple RESTful web service with journey, cradle, winston, optimist, and http-console.", "tag" : "", "html_url" : "https://github.com/indexzero/nodejs-intro" } },
{ "arrangeable_values" : { "description" : "A Backbone alternative idea", "tag" : "", "html_url" : "https://github.com/maccman/spine.todos" } }
] }
MongoDB queries return entire documents. You are looking for a field inside an array inside of the document and this will break the find().
The problem here is that any basic find() query, will return all matching documents. The find() does have the option to only return specific fields. But that will not work with your array of sub-objects. You could returns watchlists, but not watchlist entries that match.
As it stands you have two options:
Write some client-side code that loops through the documents and does the filtering. Remember that the shell is effectively a javascript driver, so you can write code in there.
Use the new aggregation framework. This will have a learning curve, but it can effectively extract the sub-items you're looking for.