I'm trying to embed a document inside an existing document using the Ruby Driver.
Here's what my primary document looks like:
db = Mongo::Connection.new.db("Portfolios")
project_collection = db.collection("Projects")
new_Project = { :url => 'http://www.tekfolio.me/billy/portfolio/focus', :author => 'Billy'}
project_collection.insert(new_Project)
After I've created my new_project and added it to my project_collection I may or may not add another collection to the same document later called assets. This is where I'm stuck. The following code doesn't seem to do anything:
new_asset = { :image_url => 'http://assets.tekfolio.me/portfolios/68fbb25a-8353-41a8-a779-4bd9762b00f2/projects/13/assets/20/focus2.PNG'}
new_Project.assest.insert(new_asset)
I'm certain I've butchered my understanding of Mongodb and the Ruby driver and the embeded document concept and would appreciate your help getting me out of this wet paper bag I can't seem to get out of ;)
Have you tried just setting the value of asset without insert and instead using update?
new_Project["asset"] = new_asset
project_collection.update({"_id" => new_Project["_id"]}, new_Project)
I think , are you trying to "update" the new_project record with the asset
it doesn't work because then you are only updating the hash in ruby, not in mongo, you have to first get the reference to the object in mongo, update it, and then save it, check this info:
http://www.mongodb.org/display/DOCS/Updating+Data+in+Mongo
(if you can, you can assign the asset before inserting, and it should work)
Related
I have this hash, which is built dynamically:
additional_values = {"grouping_id"=>1}
I want to merge it with this record object after creation via first_or_create:
result = model.where(name: 'test').first_or_create do |record|
# I'm trying to merge any record attributes that exist in my hash:
record.attributes.merge(additional_values)
# This works, but it sucks:
# record.grouping_id = data['grouping_id'] if model.name == 'Grouping'
end
#Not working:
#result.attributes>>{"id"=>1, "name"=>"Test", "grouping_id"=>nil}
I understand that if the record already exists (returned via 'first'), it won't be updated...although that would be a nice option and any recommendations on that are welcome, but the table was just dropped and recreated, so that's not the issue.
What am I missing?
I also tried using to_sym, resulting with:
additional_values = {:grouping_id=>1}
...just in case there was some weirdness I didn't know about...didn't make a difference
The problem is Hash#merge returns a new hash and then you aren't doing anything with that hash, you're just throwing it away. I would also suggest sticking to using the ActiveRecord methods for updating attributes, instead of trying to manipulate the underlying hash, such as using assign_attributes or, if you want to save the record update. Though, you may find the create_with, which can be used with find_or_create_by, useful here:
model.create_with(additional_values).find_or_create_by(name: 'test')
I can't find any documentation that I like (if at all) for first_or_create in recent rails versions, but if you like that more than find_or_create_by, then if we look at the Rails 3 documentation for first_or_create, you should be able to do with out the create_with:
model.where(name: 'test').first_or_create(additional_attributes)
I'm having an awfully difficult time figuring out how to update a MongoDB document, using the atomic '$set' operator with Mongomatic. I'm pretty sure it's Mongo's criteria/update language I'm having troubles with, not Mongomatic, but I'm willing to be proven wrong.
The link to a gist with a standalone, runnable script is here: https://gist.github.com/3835672
I'm starting out by creating a document that looks like this:
{"videos":[{"video_id":"video1"},{"video_id":"video2"}],"_id":{"$oid": "506ddd53a114604ce3000001"}}
I can get that document using a model instantiated using Mongomatic:
video_group = VideoGroup.find_one('videos.video_id' => 'video1')
Then I'm trying to set a 'views' field, by doing this:
video_group.update!({ 'videos.video_id' => 'video1' }, '$set' => { 'videos.$.views' => 123 })
That's where Mongo blows up, with the following error:
can't append to array using string field name [$]
I know this is a very common question on StackOverflow. I understand generally that the problem is that the positional operator isn't getting any matches. But even reading through dozens of responses, I still can't figure out how to express this statement in a way that works.
Am I just starting out with the wrong data structure?
It is, in fact, a mongomatic problem. You need to pass the underlying mongo ruby driver the option {:multi => true}, as well as including your criteria with the specific _id for the update sent to mongodb instead of as part of the optional parameters. Looks like a bug in mongomatic. Here is the ruby debugger transcript that I used to find it: https://gist.github.com/3836797
Note that I made a change to the file you posted, adding the line debugger before line #41, and changing line #42-44 to this:
video_group.update!({ 'videos.video_id' => 'video1', :multi => true }, '$set' => {
'videos.$.views' => 123,
})
I'm trying to insert a document that has multiple embedded documents but I have been unable to determine the structure for such a document.
I'm using Mongoid in most places but need to perform a batch document insert.
I've tried the following:
def build_records_array(records)
records.collect do |record|
record.raw_attributes["identifier"] = record.identifiers.collect { |identifier| identifier.raw_attributes }
record.raw_attributes
end
end # self.build_records_array
However the identifiers don't show up as embedded documents when I call insert. I just get a bunch of garbage in my parent document.
What is the proper structure for embedded documents?
So, I just had a typo. I wasn't thinking about Mongoid when looking at my problem. After playing around with the Mongo Driver to retrieve records Mongoid had created I discovered that I had everything right but the attribute name.
def build_records_array(records)
records.collect do |record|
record.raw_attributes["identifiers"] = record.identifiers.collect { |identifier| identifier.raw_attributes }
record.raw_attributes
end
end # build_records_array
I've to add several fields in a mongoid model, I know there is not migration with MongoDB but if I go on without dropping the DB, making rails to "regenerate" the DB entirely, it doesn't display or use the new fields at all !
What's the best way to go here ? Is there something softer than drop/reopen mongodb ?
Thanks in advance
luca
In general it should be possible to update old documents with the new fields at runtime. There is no need for migrations in MongoDB.
You maybe want to write rake tasks to update your old documents with the new fields and default values.
You could find out these documents by checking those new fields which have per default a nil value.
Update
Easy style:
If you define a new field with a default value, this value should always be used as long as you set a new one:
app/models/my_model.rb
class MyModel
include Mongoid::Document
field :name, type: String
field :data, type: String
# NEW FIELD
field :note, type: String, default: "no note given so far!"
end
If you query your database you should get your default value for documents which haven't this field before your extension:
(rails console)
MyModel.first
#=> #<MyModel …other fields…, note: "no note given so far!">
I tested this with a fresh rails stack with a current mongoid on Ruby 1.9.2 - should work with other stacks, too.
More complicated/complex style:
If you didn't set a default value, you'll get nil for this new field.
app/models/my_model.rb
class MyModel
include Mongoid::Document
field :name, type: String
field :data, type: String
# NEW FIELD
field :note, type: String
end
(rails console)
MyModel.first
#=> #<MyModel …other fields…, note: nil>
Then you could set up a rake task and migration file like in this example:
lib/tasks/my_model_migration.rake:
namespace :mymodel do
desc "MyModel migration task"
task :migrate => :environment do
require "./db/migrate.rb"
end
end
db/migrate.rb:
olds = MyModel.where(note: nil)
# Enumerator of documents without a valid :note field (= nil)
olds.each do |doc|
doc.note = "(migration) no note given yet"
# or whatever your desired default value should be
doc.save! rescue puts "Could not modify doc #{doc.id}/#{doc.name}"
# the rescue is only a failsafe statement if something goes wrong
end
Run this migration with rake mymodel:migrate.
This is only a starting point and you can extend this to a full mongoid migration engine.
The task :migrate => :environment do … is necessary, otherwise rake won't load models.
It is a little ridiculous to say that you don't need migrations with mongodb or mongoid. Any sophisticated app needs to be refactored from time to time and that can mean pulling fields out of disparate documents into a new one.
Writing one off rake tasks is way less convenient and error prone than having migrations be part of your deploy script so that it always gets run on every environment.
https://github.com/adacosta/mongoid_rails_migrations brings AR style migrations to mongoid.
You might need them less often, but you will certainly need them as an app grows.
Below is a nice code example for data migration script with mongoid and the ruby mongo driver - to be used when your updated model no longer match production data.
http://pivotallabs.com/users/lee/blog/articles/1548-mongoid-migrations-using-the-mongo-driver
I whish we would stop using "no migrations with mongoid" as slogan. It'll turn people to MongoDB for the wrong reasons, and it's only partially true. No schema, true, but data still needs to be maintained, which IMO is harder with MongoDB than RDBMs. There are other, great reasons for choosing MongoDB and it depends on your problem.
Is there any way that I can fire a raw mongo query directly in Ruby instead of converting them to the native Ruby objects?
I went through Ruby Mongo Tutorial, but I cannot find such a method anywhere.
If it were mysql, I would have fired a query something like this.
ActiveRecord::Base.connection.execute("Select * from foo")
My mongo query is a bit large and it is properly executing in the MongoDB console. What I want is to directly execute the same inside Ruby code.
Here's a (possibly) better mini-tutorial on how to get directly into the guts of your MongoDB. This might not solve your specific problem but it should get you as far as the MongoDB version of SELECT * FROM table.
First of all, you'll want a Mongo::Connection object. If
you're using MongoMapper then you can call the connection
class method on any of your MongoMapper models to get a connection
or ask MongoMapper for it directly:
connection = YourMongoModel.connection
connection = MongoMapper.connection
Otherwise I guess you'd use the from_uri constructor to build
your own connection.
Then you need to get your hands on a database, you can do this
using the array access notation, the db method, or get
the current one straight from MongoMapper:
db = connection['database_name'] # This does not support options.
db = connection.db('database_name') # This does support options.
db = MongoMapper.database # This should be configured like
# the rest of your app.
Now you have a nice shiny Mongo::DB instance in your hands.
But, you probably want a Collection to do anything interesting
and you can get that using either array access notation or the
collection method:
collection = db['collection_name']
collection = db.collection('collection_name')
Now you have something that behaves sort of like an SQL table so
you can count how many things it has or query it using find:
cursor = collection.find(:key => 'value')
cursor = collection.find({:key => 'value'}, :fields => ['just', 'these', 'fields'])
# etc.
And now you have what you're really after: a hot out of the oven Mongo::Cursor
that points at the data you're interested in. Mongo::Cursor is
an Enumerable so you have access to all your usual iterating
friends such as each, first, map, and one of my personal
favorites, each_with_object:
a = cursor.each_with_object([]) { |x, a| a.push(mangle(x)) }
There are also command and eval methods on Mongo::DB that might do what you want.
In case you are using mongoid you will find the answer to your question here.
If you're using Mongoid 3, it provides easy access to its MongoDB driver: Moped. Here's an example of accessing some raw data without using Models to access the data:
db = Mongoid::Sessions.default
# inserting a new document
collection = db[:collection_name]
collection.insert(name: 'my new document')
# finding a document
doc = collection.find(name: 'my new document').first
# "select * from collection"
collection.find.each do |document|
puts document.inspect
end