My mongodb document looks like this,
{'finance_pl':
{'S':
{
'** 200903': {'reported_eps': '19.48'},
'200806': {'reported_eps': '18.8'}
}
}
}
** 200903 ==> year 2009 month 03.
Simple way to fetch reported_eps is this
db.collection.find(
{},
{'finance_pl.S.200803.reported_eps':1}
)
but the problem is i only have the year 2008 or 2009 the month part need to generate dynamically.
I need something like this
db.collection.find(
{},
{'finance_pl.S.2008[0-9]{2}.reported_eps':1}
)
[0-9]{2} --> python regex, to match two digits.
All the example I found in the documentation and in other places have not used $regex in projection part.
I am using pymongo. How should I solve this.
You cannot currently use dynamic field names in projection like this using regex or another operator.
I am unsure if there will ever be the ability to, I am unable to find anything meaningful on the JIRA.
At the moment the best way is to restructure for your queries.
Related
Is it possible to query documents where a specific field is contained in a given string?
for example if I have these documents:
{a: 'test blabla'},
{a: 'test not'}
I would like to find all documents that field a is fully included in the string "test blabla test", so only the first document would be returned.
I know I can do it with aggregation using $indexOfCP and it is also possible with $where and mapReduce. I was wandering if it's possible to do it in find query using the standard MongoDB operators (e.g., $gt, $in).
thanks.
I can think of 2 ways you could do this:
Option 1
Using $where:
db.someCol.find( { $where: function() { return "test blabla test".indexOf(this.a) > -1; } }
Explained: Find all documents whose value of field "a" is found WITHIN some given string.
This approach is universal, as you can run any code you like, but less recommended from a performance perspective. For instance, it cannot take advantage of indexes. Read full $where considerations here: https://docs.mongodb.com/manual/reference/operator/query/where/#considerations
Option 2
Using regex matching trickery, ONLY under certain circumstances; below is an example that only works with matching that the field value is found as a starting substring of the given string:
db.someCol.find( { a : /^(t(e(s(t( (b(l(a(b(l(a( (t(e(s(t)?)?)?)?)?)?)?)?)?)?)?)?)?)?)?)?$/ } )
Explained: Break up the components of your "should-be-contained-within" string and match against all sub-possibilities of that with regex.
For your case, this option is pretty much insane, but it's worth noting as there may be specific cases (such as limited namespace matching), where you would not have to break up each letter, but some very finite set of predetermined parts. And in that case, this option could still make use of indexes, and not suffer the $where performance pentalties (as long as the complexity of the regex doesn't outweigh that benefit :)
You can use regex to search .
db.company.findOne({"companyname" : {$regex : ".*hello.*"}});
If you are using Mongo v3.6+, you can use $expr.
As you mentioned $indexOfCP can be used to get index, here it will be
{
"$expr": {
{$ne : [{$indexOfCP: ["test blabla test", "$a"]}, -1]}
}
}
The field name should be prefixed with a dollar sign ($), as $expr allows filters from aggregation pipeline.
My application has the following stack:
Sinatra on Ruby -> MongoMapper -> MongoDB
The application puts several entries in the database. In order to crosslink to other pages, I've added some sort of syntax. e.g.:
Coffee is a black, caffeinated liquid made from beans. {Tea} is made from leaves. Both drinks are sometimes enjoyed with {milk}
In this example {Tea} will link to another DB entry about tea.
I'm trying to query my mongoDB about all 'linked terms'. Usually in ruby I would do something like this: /{([a-zA-Z0-9])+}/ where the () will return a matched string. In mongo however I get the whole record.
How can I get mongo to return me only the matched parts of the record I'm looking for. So for the example above it would return:
["Tea", "milk"]
I'm trying to avoid pulling the entire record into Ruby and processing them there
I don't know if I understand.
db.yourColl.aggregate([
{
$match:{"yourKey":{$regex:'[a-zA-Z0-9]', "$options" : "i"}}
},
{
$group:{
_id:null,
tot:{$push:"$yourKey"}
}
}])
If you don't want to have duplicate in totuse $addToSet
The way I solved this problem is using the string aggregation commands to extract the StartingIndexCP, ending indexCP and substrCP commands to extract the string I wanted. Since you could have multiple of these {} you need to have a projection to identify these CP indices in one shot and have another projection to extract the words you need. Hope this helps.
I want to be able to search for my objects by searching for the last 4 characters of the id. How can I do that?
Book.where(_id: params[:q])
Where the param would be something like a3f4, and in this case the actual id for the object that I want to be found would be:
bc313c1f5053b66121a8a3f4
Notice the last for characters are what we searched for. How can I search for just "part" of my objects id? instead of having my user search manually by typing in the entire id?
I found in MongoDB's help docs, that I can provide a regex:
db.x.find({someId : {$regex : "123\\[456\\]"}}) // use "\\" to escape
Is there a way for me to search using the regular mongo ruby driver and not using Mongoid?
Usually, in Mongoid you can search with a regexp like you normally would with a string in your call to where() ie:
Book.where(:title => /^Alice/) # returns all books with titles starting with 'Alice'
However this doesn't work in your case, because the _id field is not stored as a string, but as an ObjectID. However, you could add (and index) a field on your models which could provide this functionality for you, which you can populate in an after_create callback.
<shameless_plug>
Alternatively, if you're just looking for a shorter solution to the default Mongoid IDs, I could suggest something like mongoid_token which makes it pretty easy to add shorter tokens/ids to your Mongoid documents.
</shameless_plug>
What is the best strategy for selecting mongodb entries in which a string value contains a set of words or phrases? I'm thinking of something equivalent to mysql's LIKE function, e.g.
WHERE (TEXT LIKE "% apple %") or (TEXT LIKE "% banana %")
I've seen options that involve tokenizing the string, but this would involve building unigrams for all the text, which would be huge no?
Mongo now supports text search since 2.4.
My experience has been pretty positive
http://docs.mongodb.org/manual/applications/text-search/
You start the server with setParameter text search enabled
Then enable the index on the collection
Then search with runCommand
MongoDB has no full text search capability right now, but it's easy to use external search engines like SOLR.
I strongly discourage you trying to rebuild text search with Regex or word stemming etc. yourself. You should rather focus on your app own features :)
I am using this combination: Mongoid, Sunspot and Mongoid-Sunspot. It works very well in production, and development setup is easy.
You can use the regular expression support in MongoDB queries. More details available # the following link
http://docs.mongodb.org/manual/reference/operator/regex/
Here are two examples should the above link move again in the future:
db.collection.find( { field: /acme.*corp/i } );
db.collection.find( { field: { $regex: 'acme.*corp', $options: 'i' } } );
Somehow MongoDB built-in text search failed to meet my requirements on an existing database which used a compound index. I am now using mongoose-search-plugin and it has been working superbly well. It uses natural stemming, and distance algorithms to return a relevance score.
User.search('Malaysia Car Food',{username:1},{}, function(err, u){
console.log('Search Results: '+JSON.stringify(u));
});
I am trying to perform a regex query using PyMongo against a MongoDB server. The document structure is as follows
{
"files": [
"File 1",
"File 2",
"File 3",
"File 4"
],
"rootFolder": "/Location/Of/Files"
}
I want to get all the files that match the pattern *File. I tried doing this as such
db.collectionName.find({'files':'/^File/'})
Yet I get nothing back. Am I missing something, because according to the MongoDB docs this should be possible? If I perform the query in the Mongo console it works fine, does this mean the API doesn't support it or am I just using it incorrectly?
If you want to include regular expression options (such as ignore case), try this:
import re
regx = re.compile("^foo", re.IGNORECASE)
db.users.find_one({"files": regx})
Turns out regex searches are done a little differently in pymongo but is just as easy.
Regex is done as follows :
db.collectionname.find({'files':{'$regex':'^File'}})
This will match all documents that have a files property that has a item within that starts with File
To avoid the double compilation you can use the bson regex wrapper that comes with PyMongo:
>>> regx = bson.regex.Regex('^foo')
>>> db.users.find_one({"files": regx})
Regex just stores the string without trying to compile it, so find_one can then detect the argument as a 'Regex' type and form the appropriate Mongo query.
I feel this way is slightly more Pythonic than the other top answer, e.g.:
>>> db.collectionname.find({'files':{'$regex':'^File'}})
It's worth reading up on the bson Regex documentation if you plan to use regex queries because there are some caveats.
The solution of re doesn't use the index at all.
You should use commands like:
db.collectionname.find({'files':{'$regex':'^File'}})
( I cannot comment below their replies, so I reply here )