There is extremely weird thing happening on my database. I have a query:
db.Tag.find({"word":"foo"})
this thing matches one object. it's nice.
Now, there's second query
db.Tag.find({$or: [{"word":"foo"}]})
and the second one does not give any results.
There's some kind of magic I obviously don't understand :( What is wrong in second query?
in theory, $or requires two or more parameters, so I can fake it with:
db.Tag.find({$or: [{"word":"foo"},{"word":"foo"}]})
but still, no results.
Your second query is perfectly fine, and it should work. Though the docs says, that $or performs logical operation on array of two or more expression, but it would work for single expression also.
Here's a sample that you can see, and try out, to get it to work: -
> db.col.insert({"foo": "Rohit"})
> db.col.insert({"foo": "Aman", "bar": "Rohit"})
>
> db.col.find({"foo": "Rohit"})
{ "_id" : ObjectId("50ed6bb1a401d9b4576417f7"), "foo" : "Rohit" }
> db.col.find({$or: [{"foo": "Rohit"}]})
{ "_id" : ObjectId("50ed6bb1a401d9b4576417f7"), "foo" : "Rohit" }
So, as you can see, both your query when used for my collection works fine. So, there is certainly something wrong somewhere else. Are you sure you have data in your collection?
Okaay, server admin installed mongodb from debian repo. Debian repo had 1.4.4 version of mongodb, aandd looks like $or is simply not yet supported out there :P
Related
I'm trying to check a collection to see if there is at least one documents that match a specific set of values.
I've tried reading the documentation at https://github.com/mongodb/mongo-go-driver#usage, but I can't seem to find much help there. I'm pretty new to MongoDB & Go, I believe that this is more a problem of my lack of experience.
Here is a sample query from Studio 3T that I'm trying to run with mongo-go-driver:
db.getCollection("events").find(
{
"event.eventType" : "OSR",
"context.vehicleId" : NumberInt(919514),
"ts" : {
"$gte" : ISODate("2019-06-21T21:38:43.022+0000")
}
}
).limit(1);
It seems that the context.FindOne method will do what I want (and eliminating the need for the .limit(1)). I thought that it would be straight forward to "port" this to Go and the mongo-go-driver.
I can sort of make this work, for example I have the following which will find me all the OSR:
var query = &bson.D{
{"event.eventType", "OSR"},
}
result := bson.D{}
e := collection.FindOne(context.TODO(), query).Decode(&result)
This will return me one document. Now, if I want to include the vehicleId value, and I update the query to:
var query = &bson.D{
{"event.eventType", "OSR"},
{"context.vehicleId", 919514},
}
No documents are returned. I haven't bother to expand query to include the ts field yet.
I would expect at to still have at least one document returned, but nothing is showing up. Does anybody have some tips, suggestions or guidance on what I'm doing wrong (or perhaps how I can do this better)?
Not quite sure, but have you tried with bson.M instead of bson.D?
It seems like it's working for me at least.
query := &bson.M{
"event.eventType": "OSR",
"context.vehicleId": 919514,
}
Please refer to the docs for more information.
Also, like #owlwalks said, are you sure, you're in the right collection?
It must be a silly mistake but I can't find it.
When I run db.getCollection('communes').findOne({}),
I obtain:
{
"_id" : ObjectId("59b851a19db72301ae771c57"),
"COMMUNE" : "ALAA6",
"LIBGEO" : "ROHRBACH",
"PAYS" : "Allemagne"
}
which is fine.
But when I run db.getCollection('communes').findOne({COMMUNE: "ALAA6"}), it returns nothing!
For strange reasons, filtering on other fields work, so when I run db.getCollection('communes').findOne({LIBGEO: "ROHRBACH"}), it returns the result. Same thing filtering on "PAYS".
Adding quotes around COMMUNE, i.e. running db.getCollection('communes').findOne({"COMMUNE": "ALAA6"}) or using find instead of findOne doesn't change anything.
Any idea?
Ok, my fault. The collection has been created from an Excel export, and it seems the first column contains a strange character. Querying from the Robo3T client did not show it, but querying from Python returns:
{'LIBGEO': 'ROHRBACH',
'PAYS': 'Allemagne',
'_id': ObjectId('59b851a19db72301ae771c57'),
'\ufeffCOMMUNE': 'ALAA6'}
so obviously the \ufeffchar before COMMUNEshould be removed...
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 $addToSet
The way I solved this problem is using the string aggregation commands to extract the StartingIndexCP, ending indexCP and substrCP commands to extract the string I wanted. Since you could have multiple of these {} you need to have a projection to identify these CP indices in one shot and have another projection to extract the words you need. Hope this helps.
the following fails:
db.test.update({_id:102},{$pushAll:{our_days:["sat","thurs","frid"]}, country:"XYZ"}, {upsert:true})
error message: "Invalid modifier specified: country"
The correct way seems to be:
db.test.update({_id:102},{$pushAll:{our_days:["sat","thurs","frid"]}, $set:{country:"XYZ"}}, {upsert:true})
So is it the case that I cannot mix modifiers like "$pushAll" with simple assignments like field:value, in the same update document? Instead I have to use the $set modifier for simple assignments?
Is there anything in the docs that describes this behaviour?
This happens because db.test.update({_id : 1}, {country : 1}) will just change the whole document to country = 1 and thus removing everything else.
So most probably mongo being smart tells you: You want to update specific element and at the same time to remove everything (and that element as well) to substitute it with country = 1. Most probably this is not what you want. So I would rather rise an error.
Regarding the documentation - I think that the best way is to reread mongodb update.
I have an app using Mongoid on top of MongoDB and an update is failing silently.
The code looks like this:
# Are we getting a new attribute? Yes we are!
p "attr first name = #{#attributes['first_name']}"
if user.update_attributes!(#attributes)
u = User.find(params[:id]).to_json
end
No exception is thrown in this code. So I looked at my MongoDB log and constructed this query based on what mongo is trying to do:
db.users.update({ "_id": "4d5561276ce886c496000001" }, { $set: { "first_name": "Erinamodobo" } }, false);
Now this does not cause any exceptions but when I grab the record that was supposed to be updated with this query:
db.users.find({"email":"escharling#somecompany.com"})
I see that the "first_name" attribute has not been updated.
Any idea why this could be happening? Sounds like something stupid.
Thanks!
You need to find out what
user.update_attributes!(#attributes)
is actually doing. This could be an issue with Mongoid. When you configure Mongoid, you can set up a logger. There you should be able to see what the driver is writing to MongoDB, and that should help answer your question. The next best thing is to post your code to the Mongoid mailing list (http://groups.google.com/group/mongoid) where people who work with Mongoid all the time will probably know what's going on.
Updating Mongoid to the latest rc.7 fixed this issue
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