When I create Collection::View instance with:
client = Mongo::Client.new('mongodb://127.0.0.1:27017/test')
view = client[:users].find( { name: "Sally" } )
=> #<Mongo::Collection::View:0x69824029475340 namespace='test.users' #filter={"name" => "Sally"} #options={}>
How I can change filter hash of this instance later? This does not work:
view.filter.merge!("age" => 30)
=> #FrozenError: can't modify frozen BSON::Document
I don't think you can. .filter is a method which takes arguments. It is not a hash.
See examples
and also search the code
However you might be able to do something like:
view = lambda { |hash| client[:users].find(hash) }
search_params = { name: "Sally" }
view.(search_params)
view.(search_params.merge!({foo: 'bar'}))
Related
I'm receving events in Logstash containing measurement, values and tags. I do not know ahead of time what field there are and what tags. So i wanted to do something like this:
input {
http {}
}
filter {
ruby {
code => '
tags = event.get("stats_tags").split(",")
samples = event.get("stats_samples").split(" ")
datapoints = {}
samples.each {|s|
splat = s.split(" ")
datapoints[splat[0]] = splat[1]
}
event.set("[#metadata][stats-send-as-tags]", tags)
event.set("[#metadata][stats-datapoints]", datapoints)
'
}
}
output {
influxdb {
host => "influxdb"
db => "events_db"
measurement => measurement
send_as_tags => [#metadata][stats-send-as-tags]
data_points => [#metadata][stats-datapoints]
}
}
But this produce error. After much googling to no avail i'm starting to think this is imposible.
Is there a way to pass hash and array from event field to output/filter configuration?
EDIT: If i doublequote it, the error i'm getting is
output {
influxdb {
# This setting must be a hash
# This field must contain an even number of items, got 1
data_points => "[#metadata][stats-datapoints]"
...
}
}
I have some quite simple .NET logic that I'm transplanting into a Scala codebase, and I don't really know the first thing about Scala. It includes a LINQ query that groups a collection of tagged objects by making use of an anonymous type projection to flatten and join, followed by grouping, eg:
var q = things.SelectMany(t => t.Tags, (t, tag) => new { Thing = t, Tag = tag })
.GroupBy(x => x.Tag, x => x.Thing);
In Scala it looks like flatMap might be of use, but I can't figure out how to combine it with groupBy via an anonymous.
Is this kind of thing a lot more complicated in Scala, or am I missing something simple?
UPDATE:
I ended up going with:
things.flatMap(t => t.Tags.map(x => (x,t))).groupBy(x => x._1)
and then of course later on when I access a value in the map I need to do:
.map(x => x._2)
to get the groups out of the tuple.
Simple when you know how!
Seems to me you want to do something like.
case class Tag(tag:String)
case class Thing(Tags : Seq[Tag])
val things :Seq[Thing] = Seq(Thing(Seq(Tag(""))))
val q = things.map {
thing => new {
val Thing = thing
val Tags = thing.Tags
}
}.flatMap {
thingAndTags => thingAndTags.Tags.map {
tag => new {
val Thing = thingAndTags.Thing
val Tag = tag
}
}
}. groupBy {
thingAndTag => thingAndTag.Tag
}.map {
tagAndSeqOfThingAndTags =>
tagAndSeqOfThingAndTags._1 -> tagAndSeqOfThingAndTags._2.map(x => x.Thing)
}
But in Scala anonymous objects are not really common but you can use Tuple2[T1,T2] instead of all the new { val ...}s,
val q = things.map {
thing => ( thing->thing.Tags)
}.flatMap {
thingAndTags => thingAndTags._2.map {
tag => (thingAndTags._1, tag)
}
}.groupBy {
thingAndTag => thingAndTag._2
}.map {
tagAndSeqOfThingAndTags =>
tagAndSeqOfThingAndTags._1 -> tagAndSeqOfThingAndTags._2.map(x => x._1)
}
its just a little confusing with all the ._1s and ._2s
I have the following:
data_spec['data'] = "some.awesome.values"
data_path = ""
data_spec['data'].split('.').each do |level|
data_path = "#{data_path}['#{level}']"
end
data = "site.data#{data_path}"
At this point, data equals a string: "site.data['some']['awesome']['values']"
What I need help with is using the string to get the value of: site.data['some']['awesome']['values']
site.data has the following value:
{
"some" => {
"awesome" => {
"values" => [
{
"things" => "Stuff",
"stuff" => "Things",
},
{
"more_things" => "More Stuff",
"more_stuff" => "More Things",
}
]
}
}
}
Any help is greatly appreciated. Thanks!
You could do as tadman suggested and use site.data.dig('some', 'awesome', values') if you are using ruby 2.3.0 (which is awesome and I didn't even know existed). This is probably your best choice. But if you really want to write the code yourself read below.
You were on the right track, the best way to do this is:
data_spec['data'] = "some.awesome.values"
data = nil
data_spec['data'].split('.').each do |level|
if data.nil?
data = site.data[level]
else
data = data[level]
end
end
To understand why this works first you need to understand that site.data['some']['awesome']['values'] is the same as saying: first get some then inside that get awesome then inside that get values. So our first step is retrieving the some. Since we don't have that first level yet we get it from site.data and save it to a variable data. Once we have that we just get each level after that from data and save it to data, allowing us to get deeper and deeper into the hash.
So using your example data would initally look like this:
{"awesome" => {
"values" => [
{
"things" => "Stuff",
"stuff" => "Things",
},
{
"more_things" => "More Stuff",
"more_stuff" => "More Things",
}
]
}
}
Then this:
{"values" => [
{
"things" => "Stuff",
"stuff" => "Things",
},
{
"more_things" => "More Stuff",
"more_stuff" => "More Things",
}
]
}
and finally output like this:
[
{
"things" => "Stuff",
"stuff" => "Things",
},
{
"more_things" => "More Stuff",
"more_stuff" => "More Things",
}
]
If you're receiving a string like 'x.y.z' and need to navigate a nested hash, Ruby 2.3.0 includes the dig method:
spec = "some.awesome.values"
data = {
"some" => {
"awesome" => {
"values" => [
'a','b','c'
]
}
}
}
data.dig(*spec.split('.'))
# => ["a", "b", "c"]
If you don't have Ruby 2.3.0 and upgrading isn't an option you can just patch it in for now:
class Hash
def dig(*path)
path.inject(self) do |location, key|
location.respond_to?(:keys) ? location[key] : nil
end
end
end
I wrote something that does exactly this. Feel free to take any information of value from it or steal it! :)
https://github.com/keithrbennett/trick_bag/blob/master/lib/trick_bag/collections/collection_access.rb
Check out the unit tests to see how to use it:
https://github.com/keithrbennett/trick_bag/blob/master/spec/trick_bag/collections/collection_access_spec.rb
There's an accessor method that returns a lambda. Since lambdas can be called using the [] operator (method, really), you can get such a lambda and access arbitrary numbers of levels:
accessor['hostname.ip_addresses.0']
or, in your case:
require 'trick_bag'
accessor = TrickBag::CollectionsAccess.accessor(site.data)
do_something_with(accessor['some.awesome.values'])
What you are looking for is something generally looked down upon and for good reasons. But here you go - it's called eval:
binding.eval data
I am doing an mongodb aggregation using mongoid, using ModleName.collection.aggregate(pipeline) . The value returned is an array and not a Mongoid::Criteria, so if a do a first on the array, I get the first element which is of the type BSON::Document instead of ModelName. As a result, I am unable to use it as a model.
Is there a method to return a criteria instead of an array from the aggregation, or convert a bson document to a model instance?
Using mongoid (4.0.0)
I've been struggling with this on my own too. I'm afraid you have to build your "models" on your own. Let's take an example from my code:
class Searcher
# ...
def results(page: 1, per_page: 50)
pipeline = []
pipeline <<
"$match" => {
title: /#{#params['query']}/i
}
}
geoNear = {
"near" => coordinates,
"distanceField" => "distance",
"distanceMultiplier" => 3959,
"num" => 500,
"spherical" => true,
}
pipeline << {
"$geoNear" => geoNear
}
count = aggregate(pipeline).count
pipeline << { "$skip" => ((page.to_i - 1) * per_page) }
pipeline << { "$limit" => per_page }
places_hash = aggregate(pipeline)
places = places_hash.map { |attrs| Offer.new(attrs) { |o| o.new_record = false } }
# ...
places
end
def aggregate(pipeline)
Offer.collection.aggregate(pipeline)
end
end
I've omitted a lot of code from original project, just to present the way what I've been doing.
The most important thing here was the line:
places_hash.map { |attrs| Offer.new(attrs) { |o| o.new_record = false } }
Where both I'm creating an array of Offers, but additionally, manually I'm setting their new_record attribute to false, so they behave like any other documents get by simple Offer.where(...).
It's not beautiful, but it worked for me, and I could take the best of whole Aggregation Framework!
Hope that helps!
I can't chain these two scopes together in Mongomapper using an OR:
scope :comment_is_nil, where(:comment => nil)
scope :post_not_blank, where(:post.ne => "")
It should return model objects where the comment is not nil, OR the post is not blank.
This doesn't work:
Model.where("$or" => [{:comment_is_nil, :post_not_blank])
Any ideas?
Chaining scopes is an and operation so M.comment_is_nil.post_not_blank won't work as you know. MongoDB's or syntax looks like this:
Model.where(
:$or => [
{ :comment => nil },
{ :post.ne => '' }
]
)
So you need to give it an array of individual conditions by manually expanding the scopes.