mongoid

问题 With these models: class Week has_many :proofs end class Proof belongs_to :week end I want to do something like: Week.where(:proof.count.gt => 0) To find only weeks that have multiple proofs. There is one answer that seems to address this: Can rails scopes filter on the number of associated classes for a given field But in this example, there is no such attribute as proof_ids in Week since the ids are stored with the proofs. This does not work for example: Week.where(:proof_ids.gt => 0) How

问题 I'm building a simple accounting system where a user has many bills. Now I'm trying to decide if bills should be its own collection, or nested within the user. I'm leaning towards the former but I've NEVER done any noSQL stuff so I'm just going by trial and error and what I think makes sense to me. I understand that Mongo has a 4mb document size limit which is what's making me think that I should have a separate collection for bills, as these will accumulate daily and could eventually take up

问题 Using Mongoid, let's say I have the following classes: class Map include Mongoid::Document embeds_many :locations end class Location include Mongoid::Document field :x_coord, :type => Integer field :y_coord, :type => Integer embedded_in :map, :inverse_of => :locations end class Player include Mongoid::Document references_one :location end As you can see, I'm trying to model a simple game world environment where a map embeds locations, and a player references a single location as their current

问题 Using Mongoid, let's say I have the following classes: class Map include Mongoid::Document embeds_many :locations end class Location include Mongoid::Document field :x_coord, :type => Integer field :y_coord, :type => Integer embedded_in :map, :inverse_of => :locations end class Player include Mongoid::Document references_one :location end As you can see, I'm trying to model a simple game world environment where a map embeds locations, and a player references a single location as their current

问题 What inverse_of does mean in mongoid associations? What I can get by using it instead of just association without it? 回答1: In a simple relation, two models can only be related in a single way, and the name of the relation is automatically the name of the model it is related to. This is fine in most cases, but isn't always enough. inverse_of allows you to specify the relation you are referring to. This is helpful in cases where you want to use custom names for your relations. For example:

问题 I have this little test script: require 'mongo' mongo_client = Mongo::Client.new(['127.0.0.1:27017'], :database => 'test') mongo_client[:collection].insert_one({a: 1}) An this is the console output: $ ruby test.rb D, [2015-05-17T21:12:05.504986 #25257] DEBUG -- : MONGODB | Adding 127.0.0.1:27017 to the cluster. | runtime: 0.0212ms D, [2015-05-17T21:12:05.531238 #25257] DEBUG -- : MONGODB | COMMAND | namespace=admin.$cmd selector={:ismaster=>1} flags=[] limit=-1 skip=0 project=nil | runtime:

问题 What do you see as the pros and cons of using callbacks for domain logic? (I'm talking in the context of Rails and/or Ruby projects.) To start the discussion, I wanted to mention this quote from the Mongoid page on callbacks: Using callbacks for domain logic is a bad design practice, and can lead to unexpected errors that are hard to debug when callbacks in the chain halt execution. It is our recommendation to only use them for cross-cutting concerns, like queueing up background jobs. I would

问题 What do you see as the pros and cons of using callbacks for domain logic? (I'm talking in the context of Rails and/or Ruby projects.) To start the discussion, I wanted to mention this quote from the Mongoid page on callbacks: Using callbacks for domain logic is a bad design practice, and can lead to unexpected errors that are hard to debug when callbacks in the chain halt execution. It is our recommendation to only use them for cross-cutting concerns, like queueing up background jobs. I would

问题 I have a Coupon class and I want my app to check and see how many counts are left on the coupon and if the date for the coupon has expired. I have the following method in my class to check both of these. Coupon class def self.get(code) where( :code => (normalize_code(code)), :$and => [ { :$or => [ { :coupon_count.gte => 1 }, { :coupon_count => nil } ] }, { :$or => [ { :expires_at.gt => Time.now.utc }, { :expires_at => nil } ] } ] ).first end This works fine in development when I enter a

问题 I have a Coupon class and I want my app to check and see how many counts are left on the coupon and if the date for the coupon has expired. I have the following method in my class to check both of these. Coupon class def self.get(code) where( :code => (normalize_code(code)), :$and => [ { :$or => [ { :coupon_count.gte => 1 }, { :coupon_count => nil } ] }, { :$or => [ { :expires_at.gt => Time.now.utc }, { :expires_at => nil } ] } ] ).first end This works fine in development when I enter a